Postmastectomy Radiation Research Articles

Dosimetric characterization of single- and dual-port temporary tissue expanders for postmastectomy radiotherapy using Monte Carlo methods.

The aim of this work was two-fold: a) to assess two treatment planning strategies for accounting CT artifacts introduced by temporary tissue-expanders (TTEs); b) to evaluate the dosimetric impact of two commercially available and one novel TTE. The CT artifacts were managed using two strategies. 1) Identifying the metal in the RayStation treatment planning software (TPS) using image window-level adjustments, delineate a contour enclosing the artifact, and setting the density of the surrounding voxels to unity (RS1). 2) Registering a geometry template with dimensions and materials from the TTEs (RS2). Both strategies were compared for DermaSpan, AlloX2, and AlloX2-Pro TTEs using Collapsed Cone Convolution (CCC) in RayStation TPS, Monte Carlo simulations (MC) using TOPAS, and film measurements. Wax slab phantoms with metallic ports and breast phantoms with TTEs balloons were made and irradiated with a 6 MV AP beam and partial arc, respectively. Dose values along the AP direction calculated with CCC (RS2) and TOPAS (RS1 and RS2) were compared with film measurements. The impact in dose distributions was evaluated with RS2 by comparing TOPAS simulations with and without the metal port. For the wax slab phantoms, the dose differences between RS1 and RS2 were 0.5% for DermaSpan and AlloX2 but 3% for AlloX2-Pro. From TOPAS simulations of RS2, the impact in dose distributions caused by the magnet attenuation was (6.4 ± 0.4) %, (4.9 ± 0.7)%, and (2.0 ± 0.9)% for DermaSpan, AlloX2, and AlloX2-Pro, respectively. With breast phantoms, maximum differences in DVH parameters between RS1 and RS2 were as follows. For AlloX2 at the posterior region: (2.1 ± 1.0)%, (1.9 ± 1.0)% and (1.4 ± 1.0)% for D1, D10, and average dose, respectively. For AlloX2-Pro at the anterior region (-1.0 ± 1.0)%, (-0.6 ± 1.0)% and (-0.6 ± 1.0)% for D1, D10 and average dose, respectively. The impact in D10 caused by the magnet was at most (5.5 ± 1.0)% and (-0.8 ± 1.0)% for AlloX2 and AlloX2-Pro, respectively. Two strategies for accounting for CT artifacts from three breast TTEs were assessed using CCC, MC, and film measurements. This study showed that the highest differences with respect to measurements occurred with RS1 and can be mitigated if a template with the actual port geometry and materials is used.

Post-mastectomy radiation therapy in HER-2 positive breast cancer after primary systemic therapy: Pooled analysis of TRYPHAENA and NeoSphere trials

PurposeThe role of post-mastectomy radiation therapy (PMRT) following primary systemic therapy (PST) in HER-2 positive breast cancer (Her2 + BC) remains poorly understood. The current study evaluates PMRT based on the pathological response to PST in Her2 + BC. Methods and materialsTRYPHAENA and NeoSphere are randomized phase II trials that investigated PST for Her2 + BC. Our study is a pooled analysis of both trials, including 312 node-positive patients treated with HER-2 targeted PST followed by mastectomy with or without PMRT. The primary endpoint is loco-regional recurrence-free survival (LRRFS). ResultsOur analysis included 172 (55%) patients who achieved complete nodal pathological response (ypN0) and 140 (45%) patients who did not. Patients with ypN0 had a 5-year LRRFS of 97% in both, the PMRT and no PMRT, groups (p = 0.94). Patients with ypN + had 5-year LRRFS of 89% in the PMRT group and 82% in the no PMRT group (p = 0.17). Patients with ypN1 (n = 62) disease who received PMRT (n = 40) had a 5-year LRRFS of 85% as compared to 89% in those who did not (n = 22); (p = 0.60). A significant LRRFS difference was noted in patients with ypN2-3 (n = 78) disease who received PMRT (n = 53) compared to those who did not (n = 25) (5-year LRRFS 92% vs. 75%; p = 0.019). On multivariate analysis, clinical nodal disease at diagnosis and ypN0 were significantly associated with loco-regional recurrence (LRR). ConclusionsHer2 + BC patients who achieve ypN0 after PST have excellent locoregional-control which supports de-escalation of PMRT. In contrast, patients with ypN2-3 disease derive significant benefit from PMRT. Clinical nodal stage at presentation and ypN0 status are significantly associated with LRR risk in Her2 + BC.

Effect of internal port on dose distribution in post-mastectomy radiotherapy for breast cancer patients after expander breast reconstruction.

In patients with expander-based reconstruction a few dosimetric analyses detected radiation therapy dose perturbation due to the internal port of an expander, potentially leading to toxicity or loss of local control. This study aimed at adding data on this field. A dosimetric analysis was conducted in 30 chest wall treatment planning without and with correction for port artifact. In plans with artifact correction density was overwritten as 1 g/cm3. Medium, minimum and maximum chest wall doses were compared in the two plans. Both plans, with and without correction, were compared on an anthropomorphic phantom with a tissue expander on the chest covered by a bolus simulating the skin. Ex vivo dosimetry was carried out on the phantom and in vivo dosimetry in three patients by using film strips during one treatment fraction. Estimated doses and measured film doses were compared. No significant differences emerged in the minimum, medium and maximum doses in the two plans, without and with correction for port artifacts. Ex vivo and in vivo analyses showed a good correspondence between detected and calculated doses without and with correction. The port did not significantly affect dose distribution in patients who will receive post-mastectomy radiation therapy.

A Machine Learning Approach for Predicting Capsular Contracture after Postmastectomy Radiotherapy in Breast Cancer Patients

In recent years, immediate breast reconstruction after mastectomy surgery has steadily increased in the treatment pathway of breast cancer (BC) patients due to its potential impact on both the morpho-functional and aesthetic type of the breast and the quality of life. Although recent studies have demonstrated how recent radiotherapy techniques have allowed a reduction of adverse events related to breast reconstruction, capsular contracture (CC) remains the main complication after post-mastectomy radio-therapy (PMRT). In this study, we evaluated the association of the occurrence of CC with some clinical, histological and therapeutic parameters related to BC patients. We firstly performed bivariate statistical tests and we then evaluated the prognostic predictive power of the collected data by using machine learning techniques. Out of a sample of 59 patients referred to our institute, 28 patients (i.e., 47%) showed contracture after PMRT. As a result, only estrogen receptor status (ER) and molecular subtypes were significantly associated with the occurrence of CC after PMRT. Different machine learning models were trained on a subset of clinical features selected by a feature importance approach. Experimental results have shown that collected features have a non-negligible predictive power. The extreme gradient boosting classifier achieved an area under the curve (AUC) value of 68% and accuracy, sensitivity, and specificity values of 68%, 64%, and 74%, respectively. Such a support tool, after further suitable optimization and validation, would allow clinicians to identify the best therapeutic strategy and reconstructive timing.

Subpectoral Implant Placement Is Not Protective against Postmastectomy Radiotherapy-Related Complications Compared to Prepectoral Placement.

Postmastectomy radiotherapy (PMRT) is associated with altered cosmetic outcomes and higher complication rates in implant-based breast reconstruction (IBR). Conventional wisdom suggests that muscle coverage is somewhat protective against PMRT-related complications. In this study, the authors compared surgical outcomes in patients who underwent two-stage prepectoral versus subpectoral IBR in the setting of PMRT. The authors performed a retrospective cohort study of patients who underwent mastectomy and PMRT with two-stage IBR from 2016 to 2019. The primary outcome was breast-related complications, including device infection; the secondary outcome was device explantation. The authors identified 179 reconstructions (101 prepectoral and 78 subpectoral) in 172 patients with a mean follow-up time of 39.7 ± 14.4 months. There were no differences between the prepectoral and subpectoral reconstructions in rates of breast-related complications (26.7% and 21.8%, respectively; P = 0.274), device infection (18.8% and 15.4%, respectively; P = 0.307), skin flap necrosis (5.0% and 1.3%, respectively; P = 0.232), or device explantation (20.8% and 14.1%, respectively; P = 0.117). In adjusted models, compared with prepectoral device placement, subpectoral device placement was not associated with a lower risk of breast-related complications [hazard ratio (HR), 0.75; 95% confidence interval (CI), 0.41 to 1.36], device infection (HR, 0.73; 95% CI, 0.35 to 1.49), or device explantation (HR, 0.58; 95% CI, 0.28 to 1.19). Device placement plane was not predictive of complication rates in IBR in the setting of PMRT. Two-stage prepectoral IBR provides safe long-term outcomes with acceptable postoperative complication rates comparable to those with subpectoral IBR, even in the setting of PMRT. Therapeutic, III.

Prevention of Postoperative Complications by Prepectoral versus Subpectoral Breast Reconstruction: A Systematic Review and Meta-Analysis.

Implant-based breast reconstruction has evolved over time. However, the effects of prepectoral breast reconstruction (PBR) compared with those of subpectoral breast reconstruction (SBR) have not been clearly defined. Therefore, this study aimed to compare the occurrence of surgical complications between PBR and SBR to determine the procedure that is effective and relatively safe. The PubMed, Cochrane Library, and EMBASE databases were searched for studies published until April of 2021 comparing PBR and SBR following mastectomy. Two authors independently assessed the risk of bias. General information on the studies and surgical outcomes were extracted. Among 857 studies, 34 and 29 were included in the systematic review and meta-analysis, respectively. Subgroup analysis was performed to clearly compare the results of patients who underwent postmastectomy radiation therapy. Pooled results showed that prevention of capsular contracture (OR, 0.57; 95% CI, 0.41 to 0.79) and infection control (OR, 0.73; 95% CI, 0.58 to 0.92) were better with PBR than with SBR. Rates of hematoma, implant loss, seroma, skin-flap necrosis, and wound dehiscence were not significantly different between PBR and SBR. PBR considerably improved postoperative pain, BREAST-Q score, and upper arm function compared with SBR. Among postmastectomy radiation therapy patients, the incidence rates of capsular contracture were significantly lower in the PBR group than in the SBR group (OR, 0.14; 95% CI, 0.05 to 0.35). The results showed that PBR had fewer postoperative complications than SBR. The authors' meta-analysis suggests that PBR could be used as an alternative technique for breast reconstruction in appropriate patients.

Can knowledge based treatment planning of VMAT for post-mastectomy locoregional radiotherapy involving internal mammary chain and supraclavicular fossa improve performance efficiency?

To validate and evaluate the performance of knowledge-based treatment planning for Volumetric Modulated Arc Radiotherapy for post-mastectomy loco-regional radiotherapy. Two knowledge-based planning (KBP) models for different dose prescriptions were built using the Eclipse RapidPlanTM v 16.1 (Varian Medical Systems, Palo Alto, USA) utilising the plans of previously treated patients with left-sided breast cancer who had undergone irradiation of the left chest wall, internal mammary nodal (IMN) region and supra-clavicular fossa (SCF). Plans of 60 and 73 patients were used to generate the KBP models for the prescriptions of 40 Gy in 15 fractions and 26 Gy in 5 fractions, respectively. A blinded review of all the clinical plans (CLI) and KBPs was done by two experienced radiation oncology consultants. Statistical analysis of the two groups was also done using the standard two-tailed paired t-test or Wilcoxon signed rank test, and p<0.05 was considered significant. A total of 20 metrics were compared. The KBPs were found to be either better (6/20) or comparable (10/20) to the CLIs for both the regimens. Dose to heart, contralateral breast,contralateral lung were either better or comparable in the KBP plans except of ipsilateral lung. Mean dose (Gy) for the ipsilateral lung are significantly (p˂0.001) higher in KBP though the values were acceptable clinically. Plans were of similar quality as per the result of the blinded review which was conducted by slice-by-slice evaluation of dose distribution for target coverage, overdose volume and dose to the OARs. However, it was also observed that treatment times in terms of monitoring units (MUs) and complexity indices are more in CLIs as compared with KBPs (p<0.001). KBP models for left-sided post-mastectomy loco-regional radiotherapy were developed and validated for clinical use. These models improved the efficiency of treatment delivery as well as work flow for VMAT planning involving both moderately hypo fractionated and ultra-hypo fractionated radiotherapy regimens.

Dosimetry Evaluation of Treatment Planning Systems in Patient-Specific 3D Printed Anthropomorphic Phantom for Breast Cancer after Mastectomy using a Single-Beam 3D-CRT Technique for Megavoltage Electron Radiation Therapy.

The patient-specific 3D printed anthropomorphic phantom is used for breast cancer after mastectomy developed by the laboratory of medical physics and biophysics, Department of Physics, Institut Teknologi Sepuluh Nopember, Indonesia. This phantom is applied to simulate and measure the radiation interactions occurring in the human body either using the treatment planning system (TPS) or direct measurement with external beam therapy (EBT) 3 film. This study aimed to provide dose measurements in the patient-specific 3D printed anthropomorphic phantom using a TPS and direct measurements using single-beam three-dimensional conformal radiation therapy (3DCRT) technique with electron energy of 6 MeV. In this experimental study, the patient-specific 3D printed anthropomorphic phantom was used for post-mastectomy radiation therapy. TPS on the phantom was conducted using a 3D-CRT technique with RayPlan 9A software. The single-beam radiation was delivered to the phantom with an angle perpendicular to the breast plane at 337.3° at 6 MeV with a total prescribed dose of 5000 cGy/25 fractions with 200 cGy per fraction. The doses at planning target volume (PTV) and right lung confirmed a non-significant difference both for TPS and direct measurement with P-values of 0.074 and 0.143, respectively. The dose at the spinal cord showed statistically significant differences with a P-value of 0.002. The result presented a similar skin dose value using either TPS or direct measurement. The patient-specific 3D printed anthropomorphic phantom for breast cancer after mastectomy on the right side has good potential as an alternative to the evaluation of dosimetry for radiation therapy.

Development and validation of nomograms for predicting survival outcomes in patients with T1-2N1 breast cancer to identify those who could not benefit from postmastectomy radiotherapy.

In this study, we aimed to develop and validate nomograms for predicting the survival outcomes in patients with T1-2N1 breast cancer to identify the patients who could not benefit from postmastectomy radiotherapy (PMRT). Data from 10191 patients with T1-2N1 breast cancer were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Of them, 6542 patients who had not received PMRT formed the training set. Concurrently, we retrospectively enrolled 419 patients from the Affiliated Hospital of North Sichuan Medical College (NSMC), and 286 patients who did not undergo PMRT formed the external validation set. The least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analyses were used for selecting prognostic factors in the training set. Using the selected factors, two prognostic nomograms were constructed. The nomograms' performance was assessed using the concordance index (C-index), calibration curves, decision curve analysis (DCA), and risk subgroup classification. The stabilized inverse probability of treatment weights (IPTWs) was used to balance the baseline characteristics of the different risk groups. Finally, the survival outcomes and effectiveness of PMRT after IPTW adjustment were evaluated using adjusted Kaplan-Meier curves and Cox regression models. The 8-year overall survival (OS) and breast cancer-specific survival (BCSS) rates for the SEER cohort were 84.3% and 90.1%, with a median follow-up time of 76 months, while those for the NSMC cohort were 84.1% and 86.9%, with a median follow-up time of 73 months. Moreover, significant differences were observed in the survival curves for the different risk subgroups (P < 0.001) in both SEER and NSMC cohorts. The subgroup analysis after adjustment by IPTW revealed that PMRT was significantly associated with improved OS and BCSS in the intermediate- (hazard ratio [HR] = 0.72, 95% confidence interval [CI]: 0.59-0.88, P=0.001; HR = 0.77, 95% CI: 0.62-0.95, P = 0.015) and high- (HR=0.66, 95% CI: 0.52-0.83, P<0.001; HR=0.74, 95% CI: 0.56-0.99, P=0.039) risk groups. However, PMRT had no significant effects on patients in the low-risk groups. According to the prognostic nomogram, we performed risk subgroup classification and found that patients in the low-risk group did not benefit from PMRT.

The use of a wearable cardioverter defibrillator during postmastectomy radiotherapy as an alternative for relocation of the pulse generator

We describe a case in which a breast cancer patient with an implantable cardioverter-defibrillator (ICD) was treated with postmastectomy followed by axillary radiation therapy. The ICD was partly within the target volume and according to the treatment planning system would receive a maximum dose of about 36 Gy. Postoperatively, the patient had a wound infection needing surgical intervention and 3 months of antibiotics. Therefore, it was decided not to relocate the ICD but instead to switch off the shock function of the ICD for the entire radiation therapy course. The ICD was successfully substituted with a wearable cardioverter defibrillator (WCD), which the patient wore during the 3-week radiation therapy period until 2 weeks after the end of treatment. The ICD function was monitored from the start of the treatment until 6 months after treatment. In situations in which an ICD needs to be switched off semipermanently, a WCD can be used as alternative. The patient in this report tolerated the WCD well. Despite the high dose received by the ICD, the device and its battery continued to function normally.

Breast cancer status, grading system, etiology, and challenges in Asia: an updated review

Abstract The number of breast cancer incidences reported worldwide has increased tremendously over the years. Scoping down to Asia, in 2020, the reported incidences of breast cancer are appalling, comprising 1,026,171 cases, occupying up to 45.4% of cases across the globe. Breast cancer is a non-communicable disease, that emerges in variegated forms, self-subsistent, and the etiology is observed to be multifactorial, dependent on the individual reproductive pattern, hormonal factors, diet, physical activity, lifestyle, and exposure to certain advent procedures. Given this complexity, breast cancer is expected to undergo a persistent increment in the number of incidences in near future, exacerbating the public health quality, regardless of race, ethnicity, geographical subgroups, and socioeconomic. In this review article, the authors examine breast cancer in multiple facets, comprising the updated statistics on breast cancer, typically in Asia; etiology of breast cancer; diagnosis of breast cancer; grading system; and challenges in breast cancer from the country’s income perspective. Realizing the ever-increasing demand for quality treatment, here, the article also contemplates common therapies in breast cancer, such as breast-conserving therapy, mastectomy, postmastectomy radiation therapy, neoadjuvant chemotherapy, axillary surgery, chemotherapy, adjuvant medical therapies, biological and targeted therapies, and endocrine therapy. This review article intended to provide a brief yet broad panoramic view of breast cancer, to readers, ranging from newcomers, existing researchers, and relevant stakeholders in the topic of interest.

Surgical Outcomes Of Post-Mastectomy Radiotherapy Following Immediate Prosthetic Breast Reconstruction: Six-Year Experience

Surgical Outcomes Of Post-Mastectomy Radiotherapy Following Immediate Prosthetic Breast Reconstruction: Six-Year Experience

Nipple Projection Change in Immediate Breast Reconstruction and Use of an Acellular Dermal Matrix Strut for Maintaining Nipple Projection.

Nipple-sparing mastectomy (NSM) has gained popularity as more studies have supported its oncologic safety. Although there have been some studies reporting complications including mastectomy flap and nipple necrosis, there have been few reports discussing the change in nipple projection following NSM. This study aimed to analyze the change in nipple projection after NSM and identify risk factors for nipple depression. In addition, the authors present a new method for maintaining nipple projection. Patients who underwent NSM between March of 2017 and December of 2020 at the authors' institute were included in this study. The authors measured the preoperative and postoperative nipple projection height and used a nipple projection ratio (NPR) to compare the change in height. Univariate and multivariate analyses were performed to examine the correlation of variables with the NPR. A total of 307 patients and 330 breasts were included in this study. There were 13 cases of nipple necrosis. The postoperative nipple height was decreased by 32.8%, which was statistically significant. In multiple linear regression analysis, the use of an acellular dermal matrix strut was positively correlated with the NPR and implant-based reconstruction and postmastectomy radiation therapy were negatively correlated with the NPR. The results of this study demonstrated that the reduction in nipple height after NSM was statistically significant. Surgeons need to be aware of these changes following NSM and explain this possibility to patients who have risk factors. The application of an acellular dermal matrix strut should be considered for the prevention of nipple reduction. Therapeutic, III.

Abstract GS4-05: Phase II randomized trial of conventional versus hypofractionated post-mastectomy proton radiotherapy

Abstract Purpose/Objectives: Proton therapy is under investigation in breast cancer as a strategy to reduce heart and lung exposure, which is associated with late cardiopulmonary adverse events and secondary malignancy. To date, studies investigating postmastectomy radiotherapy (PMRT) with protons have used conventional fractionation. We hypothesized that condensing treatment to 15 fractions would be safe based on evidence that breast cancer is more sensitive to higher dose fractions than surrounding normal tissues. Materials/Methods: We conducted a randomized non-inferiority phase II trial comparing conventional and hypofractionated proton PMRT with primary endpoint of 24-month complication rate (defined as grade 3 or higher late adverse events using CTCAE, v 4.0 and/or unplanned surgical intervention in patients undergoing mastectomy with reconstruction). With a 10% non-inferiority margin the study ensured 80% power and had a one sided-type I error rate of 0.05. Cardiotoxicity was assessed with serial transthoracic conventional and 2-dimensional speckle tracking echocardiography (2D-STE). Eligibility included age ≥ 18 years with non-inflammatory breast cancer resected by mastectomy with indications for PMRT. Assignment of treatments was balanced with respect to immediate breast reconstruction (IBR). Conventional fractionation group received 50 Gy in 25 fractions of 2 Gy, and hypofractionation group received 40.05 Gy in 15 fractions of 2.67 Gy (RBE 1.1). Target volume included the chest wall and axillary, supraclavicular, and internal mammary lymph nodes. All patients were treated with multi-field optimized pencil beam scanning (intensity modulated proton therapy). Results: Between 2016 and 2018, 82 patients were enrolled and randomized (41 conventional, 41 hypofractionation). Median patient age was 52 years. 32.9% were staged T3-T4 and 79.3% node positive at diagnosis. 57 of 82 patients (69.5%) elected IBR. The median mean heart dose was 0.49 Gy and the median ipsilateral lung volume receiving 40% of prescription or greater (V40%) was 13.6%. No significant changes on conventional or 2D-STE at end-of-treatment or 3-month follow-up compared to baseline were observed. The rate of ≥ grade 2 acute dermatitis was lower with hypofractionation (44% vs 15%, p = 0.006). Other ≥ grade 2 acute adverse events including esophagitis (0 vs 5%), infection (5% vs 2.4%) and skin hyperpigmentation (7.3% vs 4.8%) were not significantly different between the two arms. With a median follow-up of 38.3 months, the 24-month complication rate was conventional 14.6% vs hypofractionation 17.1% (absolute difference 2.4%, p=0.17, 95% CI [-, 15.7%]). In patients with IBR, 6 of 28 (21.4%) conventional and 7 of 29 (24.1%) hypofractionated patients developed complications (p =0.80). There was no significant difference in 3-year disease-free survival between the conventional (89.4%; 95% CI 80.0 – 99.8%) and hypofractionated (92.4%, 95% CI 84.5 – 100.0%) arms (p = 0.91). One local recurrence occurred in the hypofractionated arm simultaneous with regional and distant relapse. The remaining 6 recurrences were isolated distant events. Conclusions: Proton PMRT provided excellent locoregional control and normal tissue sparing. There were no subclinical echocardiographic changes indicative of radiation-induced cardiac dysfunction. Hypofractionation resulted in comparable disease control, tolerability and reconstruction outcomes as conventional fractionation. Although non-inferiority of hypofractionation could not be established based on the upper bound of the 95% confidence interval for complication rate being greater than 10%, both conventional and hypofractionation may be considered appropriate regimens for ongoing phase 3 randomized trials comparing photon and proton radiotherapy. Citation Format: Robert Mutter, Sharmila Giri, Briant Fruth, Nicholas Remmes, Aman Anand, Kathryn Ruddy, Hector Villarraga, Sebastian Santos Patarroyo, Elizabeth Yan, Kenneth Merrell, Lisa McGee, Tamara Vern-Gross, Bradley Stish, Robert Gao, Judy C. Boughey, Sean Park, Kimberly Corbin, Carlos Vargas. Phase II randomized trial of conventional versus hypofractionated post-mastectomy proton radiotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-05.

Abstract P2-15-03: Impact of radiotherapy on the long-term patient-reported outcomes of immediate breast reconstruction: The UK Brighter

Abstract Introduction: Post-mastectomy radiotherapy (PMRT) is an important component of breast cancer treatment and has been shown to improve overall survival for women with large cancers or node positive disease. The long-term effects of radiotherapy on the outcomes of immediate breast reconstruction (IBR) and how these are perceived from the patients’ perspective, however, are largely unknown. The UK Brighter study aimed to evaluate the long-term impact of PMRT on the patient-reported outcomes of IBR to support informed decision-making. Methods: Women who underwent unilateral mastectomy and/or breast reconstruction for invasive breast cancer or ductal carcinoma in situ (DCIS) in England between 1/4/2008 and 31/3/2009 were identified from National Health Service (NHS) Hospital Episode Statistics (HES), and current contact information for the surviving cohort provided by the NHS Personal Demographic Service. Women were sent a letter inviting them to complete three validated patient-reported outcome questionnaires, the BREAST Q, EQ-5D-5L and ICECAP-A, electronically or by post at a minimum of 12 years following their index surgery. Questionnaires were scored according to developers’ instructions and scores for women who had received PMRT following IBR compared with those who underwent IBR without radiotherapy, in the cohort as a whole and by reconstruction type. Results: 11,977 women were invited to participate of whom 4,207 (35.1%) completed the questionnaires. Some 1,236 (29.4%) underwent IBR with 343 (27.8%) expander/implant (EI) reconstructions, 629 (50.9%) latissimus dorsi (LD) flaps with or without (+/-) an implant, and 264 (21.4%) abdominal flap (AF) reconstructions. Of these, 388 (31.4%) (EI n=79 (20.4%); LD+/-implant n=222 (57.2%); AF n=87 (22.4%) received PMRT. In the cohort overall, women who received PMRT following IBR reported significantly lower ‘Satisfaction with Breasts’ scores at 12 years compared with those who did not receive radiotherapy (PMRT mean 56.4. standard deviation (SD) 21.5 vs. no PMRT mean 61.3, SD 20.5), p&amp;lt; 0.001). However, this difference varied across procedure types. Specifically, the ‘Satisfaction with Breasts’ scores of women receiving PMRT following AF reconstruction were 10.5 points lower than those not receiving PMRT (PMRT mean 60.9, SD 20.2; no PMRT mean 71.4, SD 19.6, p&amp;lt; 0.001). This difference was lower in in women undergoing LD reconstruction (mean with PMRT 54.3, SD 21.1; mean without PMRT 61.6, SD 20.7; p&amp;lt; 0.001). There were no significant differences in women undergoing EI reconstruction (PMRT mean 57.5, SD 23.6, no PMRT mean 53.9, SD 17.7). ‘Physical Well-being’ (chest) scores were also significantly lower in women receiving PMRT following IBR in the cohort overall (PMRT mean 78.7, SD 20.1, no PMRT 83.6, SD 18.6, p&amp;lt; 0.001) but women undergoing AF reconstruction showed the greatest difference in scores (PMRT mean 83.2, SD 17.0 vs No PMRT mean 90.1, SD 15.0, p&amp;lt; 0.001). There were no significant differences in ‘Physical Well-being’ scores for women who underwent EI reconstruction with or without PMRT. ‘Psychosocial Well-being’ scores were lower in women receiving PMRT after IBR (PMRT mean 70.8, SD 22.0, No PMRT 75.4, SD 21.0), but again, differential effects were seen by procedure type with no significant differences seen in the EI group but significant differences in scores seen in women receiving PMRT after flap-based procedures. Conclusions: Women undergoing PMRT report significantly lower long-term patient-reported outcomes of flap-based reconstruction, in particular ‘Satisfaction with Breasts’ and ‘Physical Well-being’ scores. This difference was not apparent in women undergoing EI procedures. This information should be shared with patients to help them make fully informed decisions about the type and timing of their reconstructive surgery. Citation Format: Leigh Johnson, Paul White, Ranjeet Jeevan, John Browne, Carmel Gulliver-Clarke, Joe O’Donoghue, Syed Mohiuddin, William Hollingworth, Patricia Fairbrother, Mairead MacKenzie, Chris Holcombe, Shelley Potter. Impact of radiotherapy on the long-term patient-reported outcomes of immediate breast reconstruction: The UK Brighter [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-15-03.

Abstract PD6-10: PD6-10 The impact of post mastectomy radiation therapy on clinical outcomes of male breast cancer: A meta-analysis of comparative studies

Abstract Background/Rationale: Male breast cancer accounts for less than 1 percent of all cancer diagnoses in men. Because it is rare, it does not lend itself to large, randomized trials. In general, the approach to the treatment of early, non-metastatic male breast cancer has largely been extrapolated from female breast cancer trials. Specifically, the data on early-stage post mastectomy radiation therapy (PMRT) is limited, and its benefits remain unclear. Objectives: We conducted this meta-analysis to determine the impact of PMRT on clinical outcomes of men with breast cancer. Methods: A review of the medical literature was conducted using online databases. Inclusion criteria consisted of English language, diagnosis of invasive non-metastatic male breast cancer (MBC), comparative studies of PMRT versus none, and studies that reported the incidence of local and distant recurrences as well as survival data in the compared arms. A meta-analysis using the Mantel-Haenszel method for calculating the weighted pooled relative risk (RR) under the fixed effects model. Subsequently, the heterogeneity statistic gets incorporated to calculate the summary RR under the random effects model. Results: Ten retrospective comparative studies with 3912 patients were included and analyzed. Eight studies reported survival data. Six and three studies reported local and distant recurrence incidence, respectively. PMRT did not have an impact on overall survival or distant recurrences. However, PMRT significantly lowered the RR of locoregional recurrences (RR=0.53, 95%CI 0.31-0.92). In addition, when survival was analyzed by TNM stage and N status, PMRT was found to have a significant reduction in RR of death in stage III (RR=0.85, 95%CI 0.75-0.97), N1 (RR=0.77, 95%CI 0.61-0.98), and N2 (RR=0.61, 95%CI 0.49-0.78) disease. Conclusions: This is the first meta-analysis to show that PMRT is associated with a lower relative risk of death in stage III MBC as well as N1 and N2 disease. It also demonstrates a significant reduction in RR of locoregional recurrences. In the absence of randomized clinical trials, it represents the most compelling data supporting the use of PMRT in this MBC patient population. Citation Format: Philip A. Haddad, Usman Zaheer. PD6-10 The impact of post mastectomy radiation therapy on clinical outcomes of male breast cancer: A meta-analysis of comparative studies [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD6-10.

Abstract P1-10-07: Role of postmastectomy radiation therapy in breast cancer patients according to pathologic nodal status after neoadjuvant chemotherapy

Abstract Purpose: The role of post-mastectomy radiation therapy (PMRT) in breast cancer patients after neoadjuvant chemotherapy (NAC) is highly controversial. This study aimed to evaluate the impact of PMRT according to pathologic nodal status. Methods and Materials: We retrospectively reviewed 682 patients with clinical stage II-III breast cancer who underwent NAC and mastectomy from 2013 to 2017. Of total, 596 (87.4%) received PMRT and 86 (12.6%) did not. We investigated the relationship amongst locoregional recurrence-free survival (LRRFS), disease-free survival (DFS), overall survival (OS), and various prognostic factors. Subgroup analyses to identify the patients who may benefit from PMRT were also performed. Results: The median follow-up duration was 67 months. In ypN+ patients (n = 368, 51.2%), PMRT showed significant benefit for LRRFS, DFS, and OS (all p &amp;lt; 0.001). Based on multivariate analysis, histologic grade (HG) III (hazard ratio [HR] = 3.67, p = 0.002), lymphovascular invasion (LVI) (HR = 2.38, p = 0.045), and ypN2-3 (HR = 2.37, p = 0.02) were identified as significant risk factors for poor LRRFS. In ypN1 patients with more than two factors among (i) luminal subtype (ii) HG I-II and (iii) absence of LVI, PMRT showed no significant difference in LRRFS (p = 0.18). In ypN0 patients (n = 351, 48.8%), PMRT was not significantly associated with LRRFS, DFS, and OS. However, PMRT showed better LRRFS in triple-negative breast cancer (TNBC) subtype (p = 0.04). Conclusion: PMRT had a high impact on treatment outcomes in patients with residual lymph nodes following NAC and mastectomy. Among the ypN0 patients, PMRT may be beneficial only in the TNBC subtype. Citation Format: Dowook Kim, Jin Ho Kim, In Ah Kim, Ji Hyun Chang, Kyung Hwan Shin. Role of postmastectomy radiation therapy in breast cancer patients according to pathologic nodal status after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-10-07.

Abstract ED6-3: How to reconcile novel reconstructive techniques with the need to radiate

Abstract The indication for postmastectomy radiotherapy (PMRT) is mainly based on tumor stage and the extent of lymph node involvement. The results of EBCTCG meta-analysis (EBCTCG Lancet, 2014) support the need of radiation therapy (RT) for patients with one to three axillary metastatic lymph nodes (LN), as well as for patients with &amp;gt; 3 affected LN. In nearly 40% of patients with mastectomy (ME) RT is required. According to the plastic surgery statistics report 2020 approximately 80% of patients seeking breast reconstruction in the USA receive an implant-based breast reconstruction (IBBR), while 18% undergo autologous reconstruction (ASoPS 2020). PMRT, regardless of reconstructive method, has been found to have a detrimental effect on outcomes with increased postoperative complications and decreased patient satisfaction. Nevertheless, even in this cohort the number of breast reconstruction (BR) is increasing over time. Surgical techniques for ME and BR are advancing constantly. With the increasing use of skin-sparing ME (SPM) techniques, particularly nipple-sparing ME (NSM), one stage IBBR (single-stage direct-to-implant, DTI) become more popular. With the availability of supportive materials such as synthetic/biological mesh or acellular dermal matrix (ADM) there has been a significant improvement in pre-pectoral implant reconstruction. The impact of PMRT on the outcomes of pre-pectoral IBRR has been recently summarized in a systemic review and meta-analysis by Awadeen (Aesth Plast Surg, 2022). Wound infection, capsular contraction and implant loss were significantly more frequent in the irradiated than in the non-irradiated breasts. Several studies describe the delayed/2-stage IBBR in the setting of PMRT as more promising and discuss different timings of exchange from expanders to implant. In one systematic review, PMRT to permanent implants reduced the rate of reconstructive failure compared to TE (J Surg Oncol,2015). After prosthetic-based BR and RT, conversion to autologous reconstruction can always be considered. Recommendations for immediate autologous reconstruction vary when PMRT is required. PMRT can result in wound complications, fat necrosis and volume loss, but overall cosmetic results are better than with IBBR and PMRT. When undergoing delayed reconstruction after PMRT, the optimal time from PMRT to reconstruction is unknown. In patients with a history of RT, NCCN-guidelines (V.4.2022) recommend autologous reconstruction as the preferred reconstruction option. Fat grafting, which can optimize tissue perfusion and wound healing, is playing an emerging role in breast surgery. Lipofilling can be used to improve the thickness of the mastectomy flap and to recontour breast defects after PMRT. There is an increasing awareness for better understanding of the different reconstruction types to define target volumes depending on the varying risk for residual tissue and potential recurrences. The ESTRO-ACROP guidelines discuss adapted dose distribution in accordance with the different locations of the implant (pre-or sub-pectoral) (Radiotherapy and Oncology, 2019). The risks and benefits of immediate versus delayed as well as implant-based versus autologous reconstruction must be considered for each individual patient and should be planned in a multidisciplinary setting, especially when PMRT is required. Citation Format: Christine Solbach. How to reconcile novel reconstructive techniques with the need to radiate [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr ED6-3.

Breast Cancer Tumor Board: A Radiologist’s Guide to Postmastectomy Radiation Therapy

Radiation therapy represents a pillar in the current management of breast cancer. Historically, postmastectomy radiation therapy (PMRT) has been administered only in patients with locally advanced disease and a poor prognosis. These included patients with large primary tumors at diagnosis and/or more than three metastatic axillary lymph nodes. However, during the past few decades, several factors have prompted a shift in perspective, and recommendations for PMRT have become more fluid. Guidelines for PMRT in the United States are outlined by the National Comprehensive Cancer Network and the American Society for Radiation Oncology. Because evidence to support performing PMRT is frequently discordant, the decision to offer radiation therapy often requires team discussion. These discussions are usually held in multidisciplinary tumor board meetings in which radiologists play a pivotal role by providing critical information such as the location and extent of disease. Breast reconstruction after mastectomy is optional and is safe in cases in which the patient's clinical status allows it. The preferred method in the setting of PMRT is autologous reconstruction. If this is not possible, then a two-step implant-based reconstruction is recommended. Radiation therapy does involve a risk of toxicity. Complications can be seen in acute and chronic settings and range from fluid collections and fractures to radiation-induced sarcomas. Radiologists have a key role in detecting these and other clinically relevant findings and should be prepared to recognize, interpret, and address them. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Abstract P2-14-09: Sensory Evaluation of Nipple-Areolar Complex after Nipple-Sparing Mastectomy: A Comparison of Incision Approaches

Abstract Background: Since nipple-sparing mastectomy (NSM) has been widely practiced, majority of previous studies have evaluated the effects of Nipple-areolar complex (NAC) preservation on body image adjustment. However, few have evaluated NAC sensation after NSM in a large sample size. This study aims to assess NAC sensation after NSM and compare the results according to different incisional approaches; specifically, inframammary fold (IMF) and peri-areolar. Methods: Post NSM patients from Oct 2019 to Nov 2021 have been recruited prospectively. A total of 115 patients (IMF 69 and peri-areolar 36) were evaluated for NAC sensory at various time points during follow up within 1.5 to 4 years after surgery. NAC sensation was scored by pin-prick test in a scale of 0 to 2 (0: no sensation, 1: dull sensation, 2: sharp sensation), divided in 5 areas of the NAC and summed up to a total of 10. Results: In all patients, a median of the pin-prick test total score on NAC was 3 (0-10). Pin-prick test of NAC showed numerically higher NAC sensory score in the IMF incision than in the peri-areolar group without a statistical significance (IMF: Median 4 Mean 3.83 ± 3.04, Peri-areolar Median 2 Mean 2.69 ± 3.64, p=0.062). When sensory scores were evaluated depending on NAC zones (A: Nipple, B: Upper outer, C: Upper inner, D: Lower outer, E: Lower inner) the IMF incision group showed better outcomes in zone B (p=0.015) and E (p=0.043). Simple linear regression analysis showed the possibility of incisional approach, diabetes mellitus (DM) history, previous radiotherapy of ipsilateral breast, post mastectomy radiotherapy (PMRT), adjuvant chemotherapy, tumor to nipple distance and laterality influencing NAC sensory with p&amp;lt; 0.2. When these factors were taken to multiple linear regression analysis, DM history (p=0.045), previous radiotherapy (p=0.001), postop radiotherapy (p=0.001), and adjuvant chemotherapy (p=0.001). Conclusion: NAC sensory deteriorated postoperatively in general. Scores of NAC sensation were numerically higher in the patients with IMF incision, although the difference was not statistically significant. NAC sensation was negatively affected by DM history, previous ipsilateral breast radiotherapy and post-NSM treatments such as chemotherapy and PMRT. While incision type may improve aesthetic outcomes, additional efforts are necessary to ameliorate the post-NSM NAC desensitization. Table 1. Patient characteristics Table 2. Linear regression analysis for clinical factors affecting NAC sensory Citation Format: Yoonwon Kook, Ji Soo Jang, Seung Ho Baek, Soong June Bae, Sung Gwe Ahn, Joon Jeong. Sensory Evaluation of Nipple-Areolar Complex after Nipple-Sparing Mastectomy: A Comparison of Incision Approaches [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-09.