Postmastectomy Radiation Research Articles

DIBH reduces right coronary artery and lung radiation dose in right breast cancer loco-regional radiotherapy

To determine whether deep inspiratory breath-hold (DIBH) reduces dose to organs-at-risk (OAR), in particular the right coronary artery (RCA), in women with breast cancer requiring right-sided post-mastectomy radiotherapy (PMRT) including internal mammary chain (+IMC) radiotherapy (RT). Fourteen consecutive women requiring right-sided PMRT + IMC were retrospectively identified. Nodal delineation was in accordance with European Society for Radiology and Oncology (ESTRO) guidelines and tangential chest wall fields marked. Patients were planned with Anisotropic Analytical Algorithm using free-breathing (FB) and DIBH datasets. Dose was calculated using Acuros External Beam algorithm. FB and DIBH dose comparisons were analyzed for heart, RCA and right lung, as were chest wall and IMC planning target volumes (PTVs). DIBH vs FB resulted in median decreases of: the RCA mean dose by 0.6Gray (Gy) (interquartile range (IQR) 0.1, 1.9) (p = 0.002), RCA max dose by 1.8Gy (IQR 0.8, 6.1) (p = 0.002), and V5Gy by 2.9% (IQR 0.0, 37.2) (p = 0.016). RCA data indicated no statistically significant dosimetric reduction ≥10Gy. A median reduction of 1.7Gy (c -0.0, 7.1) (p = 0.019) in maximum heart dose was recorded with DIBH vs FB; no significant difference was observed in other heart and left anterior descending coronary artery parameters. The median reduction in right lung mean dose was 2.8Gy for DIBH vs FB plans (IQR 1.6, 3.6) (p = 0.001); significant median reductions of V5Gy, V20Gy, and V30Gy were all achieved with DIBH. Chest wall PTV coverage did not significantly differ between DIBH and FB plans; IMC dosimetric coverage improved with use of DIBH (V47.5Gy, V45Gy, V42Gy). DIBH reduced OAR dose in right-sided PMRT + IMC patients. A novel finding was that DIBH decreased RCA dose. Heart and right lung dose were also decreased with DIBH, whilst optimally dosed PTVs were maintained.

Postmastectomy radiation therapy in breast cancer patients with micrometastatic disease in sentinel node dissection: A cohort study and meta-analysis

AimThe potential role of postmastectomy radiation therapy (PMRT) on prognosis in patients with T1-2 breast cancer and micrometastatic disease in sentinel lymph node dissection (SLND) has not yet been established. The aim of this study was to investigate the impact of PMRT on prognosis in patients with T1-2 breast cancer and micrometastatic in SLND. MethodA register- and population-based cohort was utilized by identifying eligible patients on the research database BcBase 3.0. Multivariate Cox regression models were applied for survival outcomes. In addition, a systematic literature review and meta-analysis including all relevant studies on this topic was performed. ResultsIn total, 956 patients fulfilling the inclusion criteria were found through the BcBaSe 3.0 with 237 (25.0 %) receiving PMRT and 719 (75.0 %) not receiving PMRT. No statistically significant differences between the two patient groups in terms of neither breast cancer-specific (adjusted Hazard Ratio (HR): 0.49; 95 % Confidence Interval (CI): 0.14 – 1.73) nor overall survival (adjusted HR: 0.63; 95 % CI: 0.29 – 1.35) was found. In the pooled analyses after literature review, PMRT did not result in better breast cancer-specific (5 studies; pooled HR: 1.06; 95 % CI: 0.88–1.27; I2 = 1 %; low certainty of evidence) or overall survival (6 studies; pooled HR: 1.01; 95 % CI: 0.91–1.13; I2 = 10 %; low certainty of evidence). ConclusionPMRT does not seem to impact survival in patients with T1 or T2 breast cancer with micrometastatic disease in SLND. Considering the low level of evidence and the relatively short follow-up of included studies, caution in interpreting the results into clinical practice is suggested.

Does Breast Surgery Type Alter Incidental Axillary Irradiation? A Dosimetric Analysis of the "Sentinel Envahi et Randomisation du Curage" SERC Trial.

An incidental axillary dose of adjuvant radiotherapy using tangential beams is usually given after breast-conserving surgery for breast cancer. The goal of this sub-study was to evaluate this incidental dose in the setting of post-mastectomy radiotherapy (PMRT) according to two different radiotherapy techniques. Patients participating in a randomized SERC trial who received PMRT in a single center were included. We collected the incidental axillary dose delivered to the Berg level 1 using different dosimetric parameters and compared two techniques using Student's t-test: three-dimensional conformal radiotherapy (3D-CRT) and volumetric arc therapy (VMAT). We analyzed radiotherapy plans from 52 patients who received PMRT from 2012 to 2021. The mean dose delivered to the Berg level 1 was 37.2 Gy. It was significantly higher with VMAT than with 3D-CRT-43.6 Gy (SD = 3.1 Gy) versus 34.8 Gy (SD = 8.6 Gy) p < 0.001. Eighty-four percent of the Berg level 1 was covered by 40 Gy isodose in the VMAT group versus 55.5% in the 3D-CRT group p < 0.001. On the Berg level 1, PMRT gives a dose at least equivalent to the one given by post-breast-conserving surgery radiotherapy, making it possible to limit completion axillary lymph node dissections in select pN1a patients treated with a mastectomy. Modern radiotherapy techniques like VMAT tend to increase this incidental dose.

Dynamic insights into infection risk over time in two-stage implant-based breast reconstruction: a retrospective cohort study.

Infections following postmastectomy implant-based breast reconstruction (IBR) can compromise surgical outcomes and lead to significant morbidity. This study aimed to discern the timing of infections in two-stage IBR and associated risk factors. A review of electronic health records was conducted on 1,096 breasts in 1,058 patients undergoing two-stage IBR at ** National University Hospital (2015-2020). Infections following the first-stage tissue expander (TE) insertion and second-stage TE exchange were analyzed separately, considering associated risk factors. Over a median follow-up of 53.5 months, infections occurred in 2.9% (32/1096) after the first stage and 4.1% (44/1070) after the second stage. Infections following the first-stage procedure exhibited a bimodal distribution across time, while those after the second-stage procedure showed a unimodal pattern. When analyzing risk factors for infection after the first-stage procedure, axillary lymph node dissection (ALND) was associated with early (≤7 weeks) infection, while both ALND and obesity were independent predictors of late (>7 weeks) infection. For infections following the second-stage procedure, obesity, postmastectomy radiotherapy, a history of expander infection, ALND, and the use of textured implants were identified as independent risk factors. Postmastectomy radiotherapy was related to non-salvaged outcomes after infection following both stages. Infections following first and second-stage IBR exhibit distinct timelines reflecting different pathophysiology. Understanding these timelines and associated risk factors will inform patient selection for IBR and aid in tailored postoperative surveillance planning. These findings contribute to refining patient suitability for IBR and optimizing personalized postoperative care strategies.

Risk factors for severe complications and salvage management in direct-to-implant immediate breast reconstruction: A retrospective study.

Controversies regarding the risk factors affecting direct-to-implant (DTI) immediate breast reconstruction still exist. This study aimed to evaluate the risk factors for severe complications in DTI breast reconstruction and explore potential salvage management strategies. We conducted a retrospective review of 238 patients (240 breasts) who underwent DTI immediate breast reconstruction between 2011 and 2020. Multivariate logistic regression analyses were used to identify the risk factors predicting severe complications. Seventeen (7.08%) reconstructed breasts experienced severe complications, of which only 5 were successfully salvaged through surgical revision, while the others failed and resulted in implant removal. Multivariate analyses demonstrated that mesh use [odds ratio (OR) = 4.054, 95% confidence interval: 1.376-11.945, P = .011] and post-mastectomy radiotherapy (odds ratio = 4.383, 95% confidence interval 1.142-16.819, P = .031) were independent predictors of severe complications. Mesh use and post-mastectomy radiotherapy for breast reconstruction increase the risk of severe complications. Despite positive surgical treatment, the successful salvage rate was poor.

Modeling of a tissue expander with a radiofrequency identification port in postmastectomy radiation therapy planning.

The purpose of this study was to evaluate the dose attenuation of Motiva Flora® (Flora, Establishment Labs, Alajuela, Costa Rica) tissue expander with a radiofrequency identification port locator and to develop a model for accurate postmastectomy radiation therapy planning. Dose attenuation was measured using an EBT3 film (Ashland, Bridgewater, NJ), and the optimal material and density assignment for the radiofrequency identification coil for dose calculation were investigated using the AcurosXB algorithm on the Eclipse (Varian Medical Systems, Palo Alto, CA) treatment planning system. Additionally, we performed in vivo dosimetry analysis using irradiation tangential to the Flora tissue expander to validate the modeling accuracy. Dose attenuations downstream of the Flora radiofrequency identification coil was 1.29% for a 6 MV X-ray and 0.99% for a 10 MV X-ray when the coil was placed perpendicular to the beam. The most suitable assignments for the material and density of the radiofrequency identification coil were aluminum and 2.27g/cm3, respectively, even though the coil was actually made of copper. Gamma analysis of in vivo dosimetry with criteria of 3% and 2mm did not fail in the coil region. Therefore, we conclude that the model is reasonable for clinical use.

Skin perfusion and oxygen saturation after mastectomy and radiation therapy in breast cancer patients

The pathophysiological mechanism behind complications associated with postmastectomy radiotherapy (PMRT) and subsequent implant-based breast reconstruction are not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion and saturation in the skin after mastectomy and assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate – MN).Skin microvascular perfusion and oxygenation >2 years after PMRT were measured using white light diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) in the irradiated chest wall of 31 women with the contralateral breast as a control. In the non-irradiated breast, the perfusion after application of MN (median 0.84, 25th–75th centile 0.59–1.02 % RBC × mm/s) was higher compared to the irradiated chest wall (median 0.51, 25th–75th centile 0.21–0.68 % RBC × mm/s, p < 0.001). The same phenomenon was noted for saturation (median 91 %, 25th–75th centile 89–94 % compared to 89 % 25th–75th centile 77–93 %, p = 0.001). Eight of the women (26%) had a ≥10 % difference in skin oxygenation between the non-irradiated breast and the irradiated chest wall.These results indicate that late microvascular changes caused by radiotherapy of the chest wall significantly affect skin perfusion and oxygenation.

Assessment of Postmastectomy Radiation Therapy Receipt by Age and Association With Outcomes in Women With Breast Cancer

PurposePostmastectomy radiation therapy (PMRT) reduces locoregional recurrence (LRR) and improves overall survival (OS) in patients with breast cancer. Young age has been recognized as a risk factor for LRR. The primary objective of this study was to determine if recommendations for PMRT differed among patients younger than 50 years as compared to women aged 50 years or older. MethodsWe reviewed medical records of patients with breast cancer who underwent mastectomy with or without PMRT from 2010 through 2018. Univariable and multivariable models were used to estimate the association of age with PMRT. ResultsOf 2471 patients, 839 (34%) were <50 years; 1632 (66%) were ≥50 years. Patients <50 years had a higher percentage of grade 3 tumors, hormone receptor (HR) negative and/or Her-2/neu positive tumors, clinical stage T2/T3 tumors, and nodal involvement. Compared with patients ≥50 years, patients <50 years were more likely to undergo PMRT (OR 1.57; P = .001) and regional node irradiation (RNI) to the internal mammary nodes. Advanced clinical and pathologic stage, invasive tumor histology, the presence of lymphovascular invasion, and treatment with systemic chemotherapy were predictors of PMRT receipt for patients <50 years (P < .05). PMRT was associated with improved OS and recurrence free survival (RFS) among all patients (P < .01). ConclusionPatients <50 years were more likely to undergo PMRT and to receive RNI to the internal mammary nodes but were also more likely to have other risk factors for recurrence that would warrant a PMRT recommendation. PMRT improved OS and RFS for all patients.

The Role of Adjuvant Radiotherapy in the Treatment of Breast Cancer.

The role of postmastectomy radiotherapy and regional nodal irradiation after radical mastectomy is defined in high-risk patients with locally advanced tumors, positive margins, and unfavorable biology. The benefit of postmastectomy radiotherapy in intermediate-risk patients (T3N0 tumors) remains a matter of controversy. It has been demonstrated that radiotherapy after breast-conserving surgery lowers the locoregional recurrence rate compared with surgery alone and improves the overall survival rate. In patients with four or more positive lymph nodes or extracapsular extension, regional lymph node irradiation is indicated regardless of the surgery type (breast-conserving surgery or mastectomy). Despite the consensus that patients with more than three positive lymph nodes should be treated with radiotherapy, there is controversy regarding the recommendations for patients with one to three involved lymph nodes. In patients with N0 disease with negative findings on axillary surgery, there is a trend to administer regional lymph node irradiation in patients with a high risk of recurrence. In patients treated with neoadjuvant systemic therapy and mastectomy, adjuvant radiotherapy should be administered in cases of clinical stage III and/or ≥ypN1. In patients treated with neoadjuvant systemic therapy and breast-conserving surgery, postoperative radiotherapy is indicated irrespective of pathological response.

Radiotherapy statements of the 18th St.Gallen International Breast Cancer Consensus Conference-aGerman expert perspective.

To summarize the radiotherapy-relevant statements of the 18th St.Gallen Breast Cancer Consensus Conference and interpret the findings in light of German guideline recommendations. Statements and voting results from the 18th St.Gallen International Breast Cancer Consensus Conference were collected and analyzed according to their relevance for the radiation oncology community. The voting results were discussed in two hybrid meetings among the authors of this manuscript on March 18 and 19, 2023, in light of the German S3 guideline and the 2023 version of the Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) guidelines. There was ahigh level of agreement between the radiotherapy-related statements of the 18th St.Gallen International Breast Cancer Consensus Conference and the German S3 and AGO guidelines. Discrepancies include the impact of number of lymph node metastases for the indication for postmastectomy radiotherapy.

Microcirculatory changes in the skin after postmastectomy radiotherapy in women with breast cancer

Postmastectomy radiotherapy (PMRT) increases the risk for complications after breast reconstruction. The pathophysiological mechanism underlying this increased risk is not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion in the skin directly after, and at 2 and 6 months after PMRT and to assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate—MN) after PMRT. Skin microvascular responses after PMRT were measured on two sites in the irradiated chest wall of 22 women before, immediately after, and at 2 and 6 months after unilateral PMRT with the contralateral breast as a control. A significant increase in basal skin perfusion was observed in the irradiated chest wall immediately after RT (p < 0.0001). At 2 and 6 months after RT, there was no longer a difference in basal skin perfusion compared to the contralateral breast and compared to baseline. Similarly, the blood flow response in the skin after application of MN was stronger immediately after RT compared to before RT (p < 0.0001), but there was no difference at later time points. These results indicate that the increased risk for complications after surgical procedures are not directly related to changes in skin perfusion and microvascular responsiveness observed after postmastectomy RT.

Investigation of the effect of bolus on skin dose in breast cancer treatment with tomotherapy and LINAC radiotherapy devices

In postmastectomy radiation therapy (PMRT), it is important that the chest wall skin is included in the target volume and receives an adequate dose. This study aims to investigate the effect of bolus on skin dose in breast cancer treatment with Tomotherapy and LINAC radiotherapy devices and to examine the accuracy of the surface dose calculated by treatment planning system (TPS) with thermoluminescence dosimetry (TLD). Female Alderson Rando Phantom's chest wall is virtually divided into 9 regions. Computed tomography (CT) images of the phantom were obtained with a section thickness of 3 mm. Two plans, with and without bolus, were created for each of the helical tomotherapy (HT), intensity-modulated radiotherapy (IMRT) and field-in-field (FiF) techniques. A bolus thickness of 0.5 cm was used for all bolus plans. Doses calculated from TPSs were obtained for 88 predetermined points on the chest wall. After irradiation, doses measured with TLDs were obtained. The effect of bolus use on the chest wall surface was examined. The increase in surface dose due to bolus use was 50.35%, 55.35% and 68.56% for HT, IMRT and FiF techniques in TPS, respectively. This increase in TLD measurements was 58.18%, 30.90% and 46.31% for HT, IMRT and FiF techniques, respectively. The best agreement between TPS and TLD doses for bolus and non-bolus plans was found in the HT technique. The difference between TPS and TLD doses decreased within the three treatment techniques due to bolus use. Since the chest wall skin cannot receive the required dose in IMRT and FiF techniques, bolus use is recommended until acute skin reactions occur. There is no need to use a bolus for the HT technique.

Reevaluating Axillary Lymph Node Dissection in Total Mastectomy for Low Axillary Burden Breast Cancer: Insights from a Meta-Analysis including the SINODAR-ONE Trial.

Complete axillary lymph node dissection (cALND) was previously the standard of care for breast cancer (BC) patients with axillary node disease or macro-metastases found via sentinel lymph node biopsy (SLNB). However, due to significant morbidity, contemporary management now considers a more selective approach, influenced by studies like ACOSOG Z0011. This trial showed that cALND could be omitted without compromising local control or survival in patients with low axillary nodal disease burden undergoing breast-conserving therapy, radiotherapy, and systemic therapy. The relevance of this approach for women with low axillary nodal burden undergoing total mastectomy (TM) remained unclear. A PubMed search up to September 2023 identified 147 relevant studies, with 6 meeting the inclusion criteria, involving 4184 patients with BC and low-volume axillary disease (1-3 positive lymph nodes) undergoing TM. Postmastectomy radiotherapy receipt was similar in both groups. After a mean 7.2-year follow-up, both the pooled results and the meta-analysis revealed no significant differences in overall survival. The combined analysis of the published studies, including the subgroup analysis of the SINODAR-One trial, indicates no survival advantage for cALND over SLNB in T1-T2 breast cancer patients with 1-3 positive sentinel lymph nodes (pN1) undergoing mastectomy. This suggests that, following a multidisciplinary evaluation, cALND can be safely omitted. However, the impact of other patient, tumor, and treatment factors on survival requires consideration and therefore further prospective trials are needed for conclusive validation.

Examining the effect of bolus use on skin dose during postmastectomy radiotherapy using in vivo thermoluminescence dosimetry: An IMRT and a 3DCRT study

For postmastectomy radiation therapy (PMRT), it is extremely important that the chest wall skin receives adequate dose. The aim of this prospective study was to evaluate the effect of bolus in breast cancer patients treated with 3D conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques by in vivo dosimetry. The study included 20 mastectomized breast cancer patients. Nine different points were marked on the chest wall surface of the patients before computed tomography (CT). It was ensured that the dose reading points were the same in treatment planning system (TPS) and in-vivo measurements. Half of the patients in the study group were treated with IMRT and the other half with 3D-CRT technique. 3D-CRT and IMRT patients were planned to be treated with bolus every other day. Dose distributions for the presence and absence of bolus were obtained from the chest wall skin of each patient. In in-vivo dose measurements in IMRT patients, the mean skin dose without bolus was 152.06 cGy, while the mean skin dose increased to 213.95 cGy with the use of bolus. In the 3D-CRT technique, the mean chest wall dose in TPS was 146.78 cGy and 201.1 cGy for non-bolus and bolus plans, respectively. For both treatment techniques, the skin dose calculated by TPS was lower than in-vivo dose measurements. In this study, it was observed that the use of bolus increased the skin dose sufficiently. It was also observed that skin doses were more homogeneous in 3D-CRT technique than IMRT technique. It was observed that TPS has significant deficiencies in dose calculation in the evaluation of skin doses in breast radiotherapy, therefore, it is recommended to use in-vivo dosimetric methods for control.

Challenges in Autologous Breast Reconstruction: A Review of Recommendations.

Breast reconstruction is an integral part of breast cancer treatment and offers significant psychosocial benefits for patients undergoing mastectomy as a part of their treatment plan. Autologous breast reconstruction (ABR) utilizes a patient's own tissue to reconstruct the mastectomy defect, obviating the need for the implantation of a foreign object. As the field of plastic surgery progresses, ABR has become an excellent option for the recreation of a native breast mount. With that said, there are patient populations who present unique challenges when optimizing an aesthetic ABR result. We aim to discuss these challenging groups, including patients with both high and low body mass index (BMI), patients with a history of massive weight loss, patients who require post-mastectomy radiation therapy (PMRT), and patients electing for unilateral procedures where the surgeon attempts to match the reconstructed breast with the native breast. In our discussion, we review the literature recommendations for management as well as our experiences with our own patient cases. Ultimately, we believe this procedure can be performed in a wide variety of patient types and can be offered to those who may not be considered the "ideal" candidate.

Who can benefit from postmastectomy radiotherapy among HR+/HER2- T1-2 N1M0 breast cancer patients? An explainable machine learning mortality prediction based approach.

The necessity of postmastectomy radiotherapy(PMRT) for patients with HR+/HER2 T1-2 N1M0 breast cancer remains controversial. We want to use explainable machine learning to learn the feature importance of the patients and identify the subgroup of the patients who may benefit from the PMRT. Additionally, develop tools to provide guidance to the doctors. In this study, we trained and validated 2 machine learning survival models: deep learning neural network and Cox proportional hazard model. The training dataset consisted of 35,347 patients with HR+/HER2- T1-2 N1M0 breast cancer who received mastectomies from the SEER database from 2013 to 2018. The performance of survival models were assessed using a concordance index (c-index).Then we did subgroup analysis to identify the subgroup who could benefit from PMRT. We also analyzed the global feature importance for the model and individual feature importance for individual survival prediction. Finally, we developed a Cloud-based recommendation system for PMRT to visualize the survival curve of each treatment plan and deployed it on the Internet. A total of 35,347 patients were included in this study. We identified that radiotherapy improved the OS in patients with tumor size >14mm and age older than 54: 5-year OS rates of 91.9 versus 87.2% (radio vs. nonradio, P <0.001) and cohort with tumor size >14mm and grade worse than well-differentiated, 5-year OS rates of 90.8 versus 82.3% (radio vs. nonradio, P <0.001).The deep learning network performed more stably and accurately in predicting patients survival than the random survival forest and Cox proportional hazard model on the internal test dataset (C-index=0.776 vs 0.641) and in the external validation(C-index=0.769 vs 0.650).Besides, the deep learning model identified several key factors that significantly influence patient survival, including tumor size, examined regional nodes, age at 45-49 years old and positive regional nodes (PRN). Patients with tumor size >14mm and age older than 54 and cohort with tumor size >14mm and grade worse than well-differentiated could benefit from the PMRT. The deep learning network performed more stably and accurately in predicting patients survival than Cox proportional hazard model on the internal test. Besides, tumor size, examined regional nodes, age at 45-49 years old and PRN are the most significant factors to the overall survival (OS).

Outcomes of Immediate versus Delayed Autologous Reconstruction with Postmastectomy Radiation: A Meta-Analysis.

Postmastectomy autologous breast reconstruction can be immediate or delayed. The safety of performing immediate breast reconstruction (IBR) and the impact of radiation on the newly reconstructed breast is not yet validated. A PubMed, Embase, and Google scholar search was conducted from inception to September 17, 2023. The authors included comparative studies that assessed complications or aesthetic outcomes of IBR versus delayed breast reconstruction (DBR) in the setting of postmastectomy radiotherapy (PMRT). The search identified 2693 articles. Thirteen were eligible for inclusion. A total of 565 patients underwent IBR followed by radiotherapy, whereas 699 had DBR. Mean follow-up time and age for both groups were comparable ( P > 0.1). None of the complications-revision surgery, infection, total flap failure, seroma, hematoma, dehiscence, or delayed wound healing-were significantly different across groups ( P > 0.1). IBR was found to have a higher risk of flap fibrosis (OR, 28.18; 95% CI, 5.15 to 154.12; P = 0.0001; I2 = 44%) and skin flap necrosis (OR, 6.12; 95% CI, 2.71 to 13.82; P < 0.0001; I2 = 27%) but a lower risk of partial flap failure (OR, 0.18; 95% CI, 0.06 to 0.58; P = 0.004; I2 = 0%) when compared with DBR. Results of fat necrosis should be interpreted with caution. Patient-reported and objective aesthetic outcomes were mostly comparable between groups. IBR in the setting of PMRT is increasingly being performed and poses a specific set of challenges that surgeons usually consider. The choice between IBR or DBR in the setting of PMRT should be an individualized decision based on patient risk factors and desires.

Machine Learning to Predict the Need for Postmastectomy Radiotherapy after Immediate Breast Reconstruction.

Post mastectomy radiotherapy (PMRT) is an independent predictor of reconstructive complications. PMRT may alter the timing and type of reconstruction recommended. This study aimed to create a machine learning model to predict the probability of requiring PMRT after immediate breast reconstruction (IBR). In this retrospective study, breast cancer patients who underwent IBR from January 2017 to December 2020 were reviewed and data were collected on 81 preoperative characteristics. Primary outcome was recommendation for PMRT. Four algorithms were compared to maximize performance and clinical utility: logistic regression, elastic net (EN), logistic lasso, and random forest (RF). The cohort was split into a development dataset (75% of cohort for training-validation) and 25% used for the test set. Model performance was evaluated using area under the receiver operating characteristic curve (AUC), precision-recall curves, and calibration plots. In a total of 800 patients, 325 (40.6%) patients were recommended to undergo PMRT. With the training-validation dataset (n = 600), model performance was logistic regression 0.73 AUC [95% confidence interval (CI) 0.65-0.80]; RF 0.77 AUC (95% CI, 0.74-0.81); EN 0.77 AUC (95% CI, 0.73-0.81); logistic lasso 0.76 AUC (95% CI, 0.72-0.80). Without significantly sacrificing performance, 81 predictive factors were reduced to 12 for prediction with the EN method. With the test dataset (n = 200), performance of the EN prediction model was confirmed [0.794 AUC (95% CI, 0.730-0.858)]. A parsimonious accurate machine learning model for predicting PMRT after IBR was developed, tested, and translated into a clinically applicable online calculator for providers and patients.

Evaluation of conventional IMRT and VMAT strategies for postmastectomy radiation therapy after immediate implant-based reconstruction using the new ESTRO-ACROP contouring guidelines.

This study evaluated the usability of conventional templates based on the new contour guidelines of the European Society of Radiation and Oncology and Advisory Committee in Radiation Oncology Practice (ESTRO-ACROP) for treatment plans of postmastectomy radiotherapy after immediate implant-based reconstruction. Intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans generated with two different treatment planning systems (TPSs, Eclipse and Monaco) were examined. Six computed tomography scans of patients aged 35-54years were retrospectively analysed who had undergone mastectomy and breast reconstruction using silicone implants after being diagnosed with left breast cancer. Six radiation oncologists participated in this study, and each of them contoured the target volume of one left breast using conventional contour (CTV-CONV) and new contour (CTV-ESTRO) methods. This study showed that compared with CTV-CONV, using CTV-ESTRO with objectives and cost functions similar to those of TPSs worsened the target volume coverage and increased the total number of monitor units. Considering the organs at risk, CTV-ESTRO tended to increase the mean dose delivered to the contralateral lung. It is concluded that the approach used for the new ESTRO-ACROP contour method cannot be applied in a manner similar to that for the conventional breast contour method, implying that the new ESTRO-ACROP contour method may require more time for improving plans for a given treatment.

Technical Refinements and Outcomes Assessment in Prepectoral Pocket Conversion After Postmastectomy Radiotherapy.

Several studies show how submuscular breast reconstruction is linked to animation deformity, shoulder dysfunction, and increased postoperative chest pain, when compared to prepectoral breast reconstruction. In solving all these life-impairing side effects, prepectoral implant pocket conversion has shown encouraging results. The aim of this study was to propose a refinement of the prepectoral implant pocket conversion applied to previously irradiated patients. We conducted a retrospective study on 42 patients who underwent previous nipple- or skin-sparing mastectomy and immediate submuscular reconstruction, followed by radiotherapy. We performed fat grafting sessions as regenerative pretreatment. Six months after the last fat graft, we performed the conversion, with prepectoral placement of micropolyurethane foam-coated implants. We investigated the preconversion and postconversion differences in upper limb range of motion, Upper Extremity Functional Index, and patient satisfaction with the breast and physical well-being of the chest. We reported a resolution of animation deformity in 100% of cases. The range of motion and the Upper Extremity Functional Index scores were statistically improved after prepectoral implant pocket conversion. BREAST-Q scores for satisfaction with the breast and physical well-being of the chest were also improved. The refined prepectoral implant pocket conversion is a reliable technique for solving animation deformity and improving quality of life in patients previously treated with submuscular reconstruction and radiotherapy.