Radiation Treatment For Breast Cancer Research Articles

PH-0163: Harmonization of breast cancer radiotherapy treatment planning in the Netherlands

PH-0163: Harmonization of breast cancer radiotherapy treatment planning in the Netherlands

Cardiorespiratory Fitness is a Strong, Independent Predictor of Radiation Induced Fatigue in Breast Cancer

Fatigue is among the most common but most poorly understood toxicities of patients undergoing radiation treatment for primary breast cancer, predisposing to poor quality of life, treatment non-compliance and comorbidity. In this prospective study, we sought to investigate whether an integrative measure of cardiopulmonary function under exercise conditions (cardiorespiratory fitness as evaluated by peak oxygen consumption, VO2peak) predicted fatigue in patients with early stage breast cancer undergoing radiation treatment. Patients with stage Tis-T2N0M0 breast cancer undergoing radiation to the breast performed a symptom-limited cardiopulmonary exercise test (CPET) on an electronic motorized treadmill test with 12-lead ECG monitoring (Mac® 5000, GE Healthcare) to assess cardiorespiratory fitness (VO2peak; ml O2.kg-1.min-1) according to standard procedures. Fatigue was assessed by the FACIT fatigue scale survey. Both assessments were performed during or after radiation therapy (typically within 30 days). To isolate the effects of radiation on fatigue and VO2peak, patients who received cytotoxic chemotherapy were excluded. All patients were treated with an opposed tangent technique to a dose of 4240 cGy in 16 fractions +/- a lumpectomy bed boost of 1000 cGy in 4 fractions. Twenty-eight patients (median age: 51.5, range 31-71) successfully performed both CPET and the FACIT surveys. The mean VO2 peak was 26.7 ml O2.kg-1.min-1(range 16.7- 41.7). The mean fatigue score was 38.6 (range 10-52, lower values indicating more fatigue). In age-adjusted analysis, lower VO2peak was a significant predictor of fatigue (r (25) = 0.49, n = 28, p = 0.009). Radiation-induced fatigue appears to be driven by a decrease in global cardiopulmonary function. Larger prospective studies are needed to further investigate this novel finding.

A case-control study of the joint effect of reproductive factors and radiation treatment for first breast cancer and risk of contralateral breast cancer in the WECARE study

ObjectiveTo examined the impact of reproductive factors on the relationship between radiation treatment (RT) for a first breast cancer and risk of contralateral breast cancer (CBC). MethodsThe Women’s Environmental Cancer and Radiation Epidemiology (WECARE) Study is a multi-center, population-based case-control study where cases are women with asynchronous CBC (N = 1521) and controls are women with unilateral breast cancer (N = 2211). Rate ratios (RR) and 95% confidence intervals (CI) were estimated using conditional logistic regression to assess the independent and joint effects of RT (ever/never and location-specific stray radiation dose to the contralateral breast [0, >0-<1Gy, ≥1Gy]) and reproductive factors (e.g., parity). ResultsNulliparous women treated with RT (≥1Gy dose) were at increased risk of CBC compared with nulliparous women not treated with RT, although this relationship did not reach statistical significance (RR = 1.34, 95% CI 0.87, 2.07). Women treated with RT who had an interval pregnancy (i.e., pregnancy after first diagnosis and before second diagnosis [in cases]/reference date [in controls]) had an increased risk of CBC compared with those who had an interval pregnancy with no RT (RR = 4.60, 95% CI 1.16, 18.28). This was most apparent for women with higher radiation doses to the contralateral breast. ConclusionAmong young female survivors of breast cancer, we found some evidence suggesting that having an interval pregnancy could increase a woman’s risk of CBC following RT for a first breast cancer. While sampling variability precludes strong interpretations, these findings suggest a role for pregnancy and hormonal factors in radiation-associated CBC.

Reducing Cardiac Radiation Dose From Breast Cancer Radiation Therapy With Breath Hold Training and Cognitive Behavioral Therapy.

The delivery of radiation therapy shares many of the challenges encountered in imaging procedures. As in imaging, such as MRI, organ motion must be reduced to a minimum, often for lengthy time periods, to effectively target the tumor during imaging-guided therapy while reducing radiation dose to nearby normal tissues. For patients, radiation therapy is frequently a stress- and anxiety-provoking medical procedure, evoking fear from negative perceptions about irradiation, confinement from immobilization devices, claustrophobia, unease with equipment, physical discomfort, and overall cancer fear. Such stress can be a profound challenge for cancer patients' emotional coping and tolerance to treatment, and particularly interferes with advanced radiation therapy procedures where active, complex and repetitive high-level cooperation is often required from the patient.In breast cancer, the most common cancer in women worldwide, radiation therapy is an indispensable component of treatment to improve tumor control and outcome in both breast-conserving therapy for early-stage disease and in advanced-stage patients. High technological complexity and high patient cooperation is required to mitigate the known cardiac toxicity and mortality from breast cancer radiation by reducing the unintended radiation dose to the heart from left breast or left chest wall irradiation. To address this, radiation treatment in daily deep inspiration breath hold (DIBH), to create greater distance between the treatment target and the heart, is increasingly practiced. While holding the promise to decrease cardiac toxicity, DIBH procedures often augment patients' baseline stress and anxiety reaction toward radiation treatment. Patients are often overwhelmed by the physical and mental demands of daily DIBH, including the nonintuitive timed and sustained coordination of abdominal thoracic muscles for prolonged breath holding.While technologies, such as DIBH, have advanced to millimeter-precision in treatment delivery and motion tracking, the "human factor" of patients' ability to cooperate and perform has been addressed much less. Both are needed to optimally deliver advanced radiation therapy with minimized normal tissue effects, while alleviating physical and cognitive distress during this challenging phase of breast cancer therapy.This article discusses physical training and psychotherapeutic integrative health approaches, applied to radiation oncology, to leverage and augment the gains enabled by advanced technology-based high-precision radiation treatment in breast cancer. Such combinations of advanced technologies with training and cognitive integrative health interventions hold the promise to provide simple feasible and low-cost means to improve patient experience, emotional outcomes and quality of life, while optimizing patient performance for advanced imaging-guided treatment procedures - paving the way to improve cardiac outcomes in breast cancer survivors.

A Signature That May Be Predictive of Early Versus Late Recurrence After Radiation Treatment for Breast Cancer That May Inform the Biology of Early, Aggressive Recurrences

Unmet clinical needs in breast cancer (BC) management include the identification of patients at high risk of local failure despite adjuvant radiation and an understanding of the biology of these recurrences. We previously reported a radiation response signature and here extend those studies to identify a signature predictive of recurrence timing (before or after 3 years). Two independent patient cohorts were used. The training cohort included 119 patients with in-breast tumor recurrence (343 total), and the validation testing cohort had 16 patients with recurrences (112 total). All patients received radiation treatment after breast-conserving surgery. Initial feature selection used Spearman rank correlation, and a linear model was trained and locked before testing and validation. Cox regression was used for univariate and multivariable analyses (UVA and MVA, respectively). Biologically related concepts were identified using gene set enrichment analysis. Spearman correlation identified 485 genes whose expression was significantly associated with recurrence time (early vs late). Feature reduction further refined the list to 41 genes retained within the signature. In training, the correlation of score to recurrence time was 0.85 (P value < 1.3 × 10-31) with an area under the curve (AUC) of 0.91. Application of this early versus late signature to an independent BC testing and validation set accurately identified patients with early versus late recurrences (Spearman correlation = 0.75, P value = .001, AUC = 0.92, sensitivity = 0.75, specificity = 1.0, positive predictive value = 1.0, and negative predictive value = 0.8). Unique associations of breast cancer intrinsic subtype to timing of local recurrence were identified. In UVA and MVA the early versus late recurrence signature remained the most significant factor associated with recurrence. Gene set enrichment analysis identified proliferation and epidermal growth factor receptor concepts associated with early recurrences and luminal and ER-signaling pathways associated with late recurrences. Knockdown of genes associated with the early and late recurrences demonstrated novel effects on proliferation and clonogenic survival, respectively. We report a breast cancer gene signature that may identify patients unlikely to respond to adjuvant radiation and may be used to predict timing of recurrences with implications for potential treatment intensification and duration of follow-up for women with breast cancer treated with radiation.

Is Faster Breast Cancer Radiation Treatment as Effective?

Is Faster Breast Cancer Radiation Treatment as Effective?

Hypofractionated radiation treatment for breast cancer: The time is now.

While there is now Level I data with long-term follow-up supporting the routine use of hypofractionated (HF) whole-breast radiation therapy (WBRT) after breast-conserving surgery, its adoption has been slow and variable. This article will review the literature supporting the efficacy and safety of hypofractionated radiation for breast cancer, discuss the radiobiological rationale specific to breast tumors, and make an argument for justifying the routine adoption of shorter, HF-WBRT courses when delivering breast radiation. Data using HF with regional nodal irradiation and in the post-mastectomy setting will also be reviewed. The aim is to provide an in-depth understanding of the use of hypofractionated radiation therapy for breast cancer, its applicability, and topics warranting future research.

Dual-isocentric volumetric modulated arc therapy in synchronous bilateral breast cancer irradiation: A dosimetric study

Introduction: In synchronous or metachronous breast cancer, bilateral breast irradiation is one of the major problems of radiation oncology. In this study, dosimetric radiation treatment of bilateral breast cancer (BBC) in two cases of synchronous bilateral mammary cancer will be discussed. In this study, a conformal radiotherapy (RT) plan for bilateral breast irradiation is discussed over two cases with synchronous BBC (sBBC). Materials and Methods: Two cases with sBBC requiring irradiation of dual breasts and regional nodal areas were chosen. Data from bilateral breast irradiation studies were used rather than dose recommendations used in unilateral breast irradiation for organs at risks. The dual-isocentric four-half-arc option was utilized in volumetric-modulated arc therapy (VMAT) plans. The dynamic sliding window method with fixed gantry angle was utilized in intensity-modulated radiation therapy (IMRT) plans. Results: Both IMRT and VMAT plans were chosen for the patients. D95% of the planning target volume supplied the desired dose prescription in the VMAT and IMRT plans of Case 1 and in the IMRT plan of Case 2, whereas the VMAT plan of Case 2 did not achieve the desired dose prescription at the target. The conformity index (CI) was the ideal plan in Case 1's VMAT plan, while Case 2's VMAT plan deviated greatly in terms of the CI value. The VMAT and IMRT plans of Case 1 and the IMRT plan of Case 2 were considered to be more homogeneous plans than the value closest to zero in terms of homogeneity index, whereas the VMAT plan of Case 2 was not considered homogeneous. Conclusion: It is recommended that in sBBC RT confined to breast only dual isometric, four half arc VMAT is an appropriate plan.

The Japanese Breast Cancer Society Clinical Practice Guideline for radiation treatment of breast cancer, 2018 edition

PurposeThe Japanese Breast Cancer Society (JBCS) Clinical Practice Guideline was revised in 2018. This article describes the revise points in the section on radiation therapy (RT).Methods and materialsThe JBCS formed task force to update the JBCS Clinical Practice Guideline 2015 edition. Background questions (BQs) deal with standard treatments of breast cancer in clinical practice. Clinical questions (CQs) highlight the important treatments in which controversy remains. The task force for RT section addressed the 10 BQs, the 10 CQs, and the 4 Future reseach questions (FQs). For each CQ, systematic literature reviews and meta-analyses were conducted, and recommendations, strength of recommendation and strength of evidence were determined according to the protocol in Morizane et al. (Minds Handbook for Clinical Practice Guideline Development, 2014).ResultsThe recommendations, the strength of recommendation and the strength of evidence were determined based on the systematic literature reviews and the meta-analyses for each CQ.ConclusionThe JBCS updated the Clinical Practice Guideline. RT represents a significant portion of the breast cancer treatment, and these recommendations regarding RT will be useful in individualized, shared decision making between physicians and patients.

Intra-Operative Radiotherapy in Breast Cancer Treatment: A Literature Review

Context: The process of direct radiation to the tumor or tumor residue during surgery known as Intraoperative Radiation Therapy (IORT) is a new promising technique in the treatment of different cancers. For a detailed review of IORT application and effectiveness in breast cancer, we conducted a review of the present literature in the field. Evidence Acquisition: In this study, the most important technologies for IORT were identified through a comprehensive study. Relevant, critical, and highly cited articles and studies were selected based on experts’ opinions. Data were summarized in sections of technology and physics, protocols, and treatment outcomes. Results: Electron beam and low-energy X-ray technologies were explained, and the physique of IORT was discussed. Due to the uncertainties of this modality and geometric complexities of post-excision treatment site, specialized treatment planning systems for IORT are necessary. In breast cancer treatment, regardless of the employed technology, IORT is applied with two main protocols: Partial Breast Irradiation and Intraoperative Boost Irradiation, each with their own advantages and disadvantages. Conclusions: Despite the controversies in acceptance and effectiveness of IORT, this technique seems to be promising for increased survival of breast cancer patients.

Factors Associated with Breast Cancer Radiation Treatment Quality Measures: Study of a Single Institution

Factors Associated with Breast Cancer Radiation Treatment Quality Measures: Study of a Single Institution

Radiation treatment in early stage triple‐negative breast cancer in New Zealand: A national database study

We aimed to investigate the impact of radiation treatment in early-stage triple negative breast cancer (TNBC). Patients with early stage (T1-3, N0-2, M0) TNBC were identified using the New Zealand breast cancer register. The outcomes of local recurrence (LRFR), local recurrence free survival (LRFS), loco-regional recurrence free rate (LRRFR), loco-regional recurrence free survival (LRRFS), breast cancer specific survival (BCSS), metastasis free (MFS) and overall survival (OS) were determined. Predefined univariate and multivariate cox regression analyses were used to explore associations between known prognostic and treatment factors. 1209 patients were identified with a median follow-up of 3.88years. The majority were post- menopausal. The mean tumour size was 26mm, the majority had grade III disease and a third were node positive. 625 patients had mastectomy and 584 had breast conservation surgery (BCS). 92% of BCS and 38% of mastectomy patients received radiation. 67% received adjuvant chemotherapy. The 5year OS was 77.6% (95% CI 74.6-80.2), 5year BSS was 82.1% (95%CI 79.1-84.7), 5year LRRFS was 73.9% (95% CI 73.87-73.93), 5year LRFS was 75.4 (75.37-75.43) and the 5year LRFR was 92.4% (95% CI 90.6-94.2). The significant prognostic/predictive factors for OS were adjuvant radiation treatment, chemotherapy, T stage, lymph node involvement and lympho-vascular space invasion. Results were similar for BSS, DMFS, LRFS and LRRFS except that LVSI was not significantly associated with BCSS, LRFS or LRRFS. When analysed by surgical type, in the WLE group, radiation was found to be significantly associated with improvement in all outcomes. In mastectomy group, radiation was not found to be significant for BCSS, LRFS, LRRFS or OS. Radiation treatment is significantly associated with improved outcomes in early stage TNBC. This argues against the hypothesis that TNBC has inherent radiation resistance.

The Potential Role of Intensity-modulated Proton Therapy in the Regional Nodal Irradiation of Breast Cancer: A Treatment Planning Study

AimsTo investigate the role of intensity-modulated proton therapy (IMPT) for regional nodal irradiation in patients with breast carcinoma in comparison with volumetric-modulated arc therapy (VMAT). Materials and methodsA cohort of 20 patients (10 in the breast-conserving surgery group and 10 post-mastectomy patients with tissue expander implants) was investigated. Proton plans were also computed using robust optimisation methods. Plan quality was assessed by means of dose–volume histograms and scored with conventional metrics. Estimates of the risk of secondary cancer induction (excess absolute risk, EAR) were carried out, taking into account fractionation, repopulation and repair. ResultsConcerning target coverage, the data proved a substantial equivalence of VMAT and IMPT: for example, coverage for the 50 Gy target, expressed in terms of V98%, was 47.8 ± 0.4, 47.6 ± 0.4, 47.3 ± 0.8, consistent with the objective of 47.5 Gy, for post-mastectomy patients for the three groups of patients. Also, the conformality of the dose distributions was similar for the two techniques, about 1.1, without statistically significant differences. Organ at risk planning aims were achieved for all structures for both techniques. The mean dose to the ipsilateral lung was 10.8 ± 1.1, 6.2 ± 0.8, 7.2 ± 1.0; for the contralateral lung was 3.2 ± 0.7, 0.3 ± 0.2, 0.4 ± 0.2; for the contralateral breast was: 3.1 ± 0.7, 0.3 ± 0.3 and 0.3 ± 0.3, whereas it was 3.9 ± 0.9, 0.4 ± 0.3 and 0.5 ± 0.5, respectively, for the heart for VMAT, IMPT and robust IMPT plans over the whole group of patients. Robust optimisation affected the near-to-maximum dose values for contralateral lung and breast, the mean dose for the heart and ipsilateral lung, with a deterioration ranging from 20 to 40% of the nominal value of IMPT plans (e.g. from 8.1 ± 6.4 to 11.4 ± 8.8 for the heart compared with 16.2 ± 5.2 for the VMAT plans). The numerical values of EAR per 10 000 patient-years were about one order of magnitude higher for VMAT than for IMPT for contralateral structures: 11.66 ± 2.01, 0.89 ± 0.80, 0.98 ± 0.77 for the contralateral breast and the three groups of plans, respectively; 14.31 ± 2.75, 1.42 ± 0.80, 1.78 ± 0.87 for the contralateral lung; and 34.86 ± 2.64, 18.85 ± 2.15, 20.98 ± 2.35 for the ipsilateral lung. ConclusionIMPT with or without robust optimisation seems to be a potentially promising approach for the radiation treatment of breast cancer when nodal volumes should be irradiated. This was measured in terms of dosimetric advantage and predicted clinical benefit. In fact, the significant reduction in estimated EAR could add further clinical value to the dosimetric sparing of the organs at risk achievable with IMPT.

A Full-Image Deep Segmenter for CT Images in Breast Cancer Radiotherapy Treatment.

Radiation therapy is one of the key cancer treatment options. To avoid adverse effects in the healthy tissue, the treatment plan needs to be based on accurate anatomical models of the patient. In this work, an automatic segmentation solution for both female breasts and the heart is constructed using deep learning. Our newly developed deep neural networks perform better than the current state-of-the-art neural networks while improving inference speed by an order of magnitude. While manual segmentation by clinicians takes around 20 min, our automatic segmentation takes less than a second with an average of 3 min manual correction time. Thus, our proposed solution can have a huge impact on the workload of clinical staff and on the standardization of care.

SP-0463 Towards less radiotherapy in breast cancer treatment

SP-0463 Towards less radiotherapy in breast cancer treatment

Abstract P5-13-18: Barriers to adjuvant radiotherapy treatment for breast cancer in a teaching hospital in Brazil

Abstract BACKGROUND: Adjuvant treatment of non-metastatic breast cancer (BC) represents an important paradigm of multimodality approach in oncology practice, with an established role for radiotherapy (RT). A delay of adjuvant radiotherapy can lead to poorer results. When chemotherapy (CT) is not indicated, RT should be initiated within 8 weeks after surgery. If CT is administered first, RT should be started within 7 months from surgery, since there is a continuous relation between time to radiotherapy and local recurrence. Brazil's public healthcare system, SUS, faces many challenges caring for cancer patients: inadequate funding, inequitable distribution of resources and services, among others. According to research done by Lins et al, around 458 linear accelerators would be necessary to supply the Brazilian public health demand and end the waiting line for radiation therapy. Currently, our healthcare system has 283 machines, which are responsible for more than 70% of our population. Furthermore, patients lack understanding of treatment windows, which is an additional hurdle. METHODS: We randomly selected 122 charts of female BC patients submitted to treatment with curative intent from 2003-2017 in Hospital das Clínicas da UFMG, the biggest teaching hospital of the 3rd largest city in Brazil. Primary endpoint was to determine median time from surgery to adjuvant radiotherapy, and second point was to determine median radiotherapy time. RESULTS: Twenty eight patients were not included in the analysis, 26 due to lack of information in the charts and two for not having received the proposed radiotherapy. Ninety four patients were included: median age was 49 years old (21-90), 21.5% were stage I, 41.9% stage II and 34.4% stage III at diagnosis. Patients received chemotherapy (neo or adjuvant), hormonotherapy, or both, according to oncologists discretion. All patients were submitted to surgery and radiotherapy. Long median times from referral to RT initiation and to radiotherapy completion were identified: 54 days and 97 days, respectively, as well as 7 months from surgery to beginning of RT (1-16) and 9 months from diagnosis to its completion (2-29).Biopsies were performed in 27 different sites and RT in 12. IntervalMedian Time (days)Biopsy to results13 (1-77)Referral to RT initiation54 (1-238)Referral to RT completion97 (43-238)RT initiation to RT completion42 (20-80) IntervalMedian Time (months)Surgery to RT initiation7 (1-16)Diagnosis to RT completion9 (2-29) CONCLUSIONS: This study shows that intervals for completion of adjuvant radiotherapy are well above recommended, mostly due to long delays in initiating radiotherapy. Although in our study all patients were conducted by the same oncology team, the system is fragmented, making it even more difficult for patients to receive multidisciplinary care and improve prognosis. There is undeniable need for more radiotherapy machines, but since their acquisition depends on costly governmental actions, we need to think about strategies that may allow us to better use the resources already available. We believe that Patient Navigation plays an important role here and were are establishing this program in our institution with Global Cancer Institute support. Citation Format: Vieira CM, Nogueira-Rodrigues A, Sousa CF, Krush L, Goss PE. Barriers to adjuvant radiotherapy treatment for breast cancer in a teaching hospital in Brazil [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-13-18.

20 Treating breast cancer with VMAT in deep inspiration breath hold: The Geneva experience

Introduction We report on the treatment management and the dosimetric results of deep inspiration breath hold (DIBH) volumetric modulated arc therapy (VMAT) treatments for breast cancer patients. Methods A total of sixty-four patients with breast cancer beneficiated from DIBH VMAT treatments since the implementation of this technique in our department in October 2016. The simulation CT (CTsim) room is equipped with the Real-time Position Management™ (RPM 1.7) Respiratory Gating (Varian) and the treatments are delivered on either a TrueBeam with Respiratory Gating or a Varian Linac with RPM. DIBH coaching is performed by the RTTs the day of CTsim. CTsim is acquired when the patient is able to maintain a reproducible and stable DIBH for at least 20 s. The “reference” breathing curve acquired at CTsim is saved, and personalized gating thresholds are defined for treatment delivery. The treatment is delivered using a 6 MV beam with 2 partial arcs (200°) and 2 “tangential-like” arcs (50°). For dosimetric analysis, patients were divided into 9 groups depending on the anatomical regions (breast and lymph nodes) included in the planning target volume (PTV), the breast laterality (50 left, 10 right and 4 double-sided irradiations) and the presence of a simultaneous integrated boost (SIB). The total dose was renormalized at the same value (50 Gy) for each group (4 different dose prescriptions and fractionations are used in Geneva). Results Patient setup is controlled with DIBH kV/kV and CBCT images. The RTTs need to continuously coach the patient as he cannot visualize its DIBH level during the session. Using DIBH technique requires additional time compared to a free breathing treatment (35 vs. 20 min per fraction). As for dosimetry, in all groups, more than 95% of the PTV received at least 95% of the prescribed dose. The dose received by 2% of the PTV did not exceed 107.3% for groups without SIB, and 111.4% for groups with SIB. Mean dose ( D mean ) to the heart was 5 Gy for groups without internal mammary chain (IMC) irradiation, 6 Gy with IMC, and reached 8 Gy for double-sided breast and whole left breast with SIB irradiations. D mean of the contralateral breast did not exceed 2.8 Gy for groups without IMC, and 3.8 Gy for groups with IMC. As for the contralateral lung: D mean was 3 Gy and 5 Gy, V 5 Gy was 20% and 40%, for groups without and with IMC respectively. For the homolateral lung, D mean was below 9.5 Gy for breast alone groups (+/-SIB) and 13.9 Gy for IMC + SIB groups, V 5 Gy was below 50% for breast alone groups, below 56.1 % for SIB groups, and below 78.7% for IMC + SIB groups. Conclusions Radiotherapy treatment of breast cancer using DIBH and a VMAT technique is more and more used in our center because of the excellent achievable OAR dose sparing and the good reproducibility of patient positioning. The additional time resource needed for this treatment modality is compensated by the gain in treatment quality.

156. Dosimetric comparison between 3D-CRT, Field in Field and VMAT techniques in the adjuvant radiotherapy treatment of breast cancer

Purpose To compare 3D-CRT, Field-in-Field (FIF) and VMAT for adjuvant radiotherapy of breast cancer. Methods 26 patients (13 with left-sided breast cancer, 13 with right-sided) treated to a prescribed dose of 40 Gy (2.667 Gy/fraction; normalized to the target mean) were considered. For all patients a 3D-CRT and a VMAT plan were simulated. 3D-CRTs were planned with 2 primary tangential fields with physical wedges and 2 additional low weighted segments. VMAT plans were performed with a Rapid Arc (RA) technique using 2 partial arc. In a subgroup of 15 patients FIF technique was implemented, combining two open fields with 2–3 segments in two tangential beam directions, without using wedges. Comparisons were performed in terms of PTV coverage and OARs dose-volume histogram (DVH) parameters, considering optimal/acceptable constraints of RTOG-1005 protocol. The dosimetric value of omolateral (lung/heart) OARs were related to the OARs volume included in the chest concavity and to OAR’s inclusion maximum depth. Results Concerning PTV, coverage was similar for the three techniques. The mean dose to OARs are summarized in the table. RA was sub-optimal for all contralateral OARs because mean doses were significantly (p Conclusions The FIF (3D-CRT) technique is similar to RA for PTV data and presents the best results all contralateral OARs. Only when (omolateral) lung and heart have an inclusion in chest concavity >1.5 cm, RA significantly reduces dose in the high DVH region.

Contouring workload in adjuvant breast cancer radiotherapy

PurposeTo measure the impact of contouring on worktime in the adjuvant radiation treatment of breast cancer, and to identify factors that might affect the measurements. Material and methodsThe dates and times of contouring clinical target volumes and organs at risk were recorded by a senior and by two junior radiation oncologists. Outcome measurements were contour times and the time from start to approval. The factors evaluated were patient age, type of surgery, radiation targets and setup, operator, planning station, part of the day and day of the week on which the contouring started. The Welch test was used to comparatively assess the measurements. ResultsTwo hundred and three cases were included in the analysis. The mean contour time per patient was 34minutes for a mean of 4.72 structures, with a mean of 7.1minutes per structure. The clinical target volume and organs at risk times did not differ significantly. The mean time from start to approval per patient was 29.4hours. Factors significantly associated with longer contour times were breast-conserving surgery (P=0.026), prone setup (P=0.002), junior operator (P<0.0001), Pinnacle planning station (P=0.026), contouring start in the morning (P=0.001), and contouring start by the end of the week (P<0.0001). Factors significantly associated with time from start to approval were age (P=0.038), junior operator (P<0.0001), planning station (P=0.016), and contouring start by the end of the week (P=0.004). ConclusionContouring is a time-consuming process. Each delineated structure influences worktime, and many factors may be targeted for optimization of the workflow. These preliminary data will serve as basis for future prospective studies to determine how to establish a cost-effective solution.

Model-basedcardiacdoseestimation in radiationtreatment of leftbreastcancer.

To develop a mathematical model for cardiac dose estimation for patients who have been treated for left-sided breast cancer without CT data. After obtaining institutionalreview board approvals, 147 patients with left-sided breast cancer were selected that were treated supine with opposed tangents. The heart blocks from the tangential fields were removed and dose calculations were performed with 6 MV beams using an advanced algorithm. This study was performed with CT data with DRR to represent a radiographic simulator image of yesteryear treatments. The beam'seye-view images showing delineated breast, lung and heart were created to represent views on radiograph. The maximum heart distance (MHD) was recorded and irradiated heart area (AREA) was computed by combination of triangles and rectangles. Based on accurate 3D dose calculation, mean dose (Dmean) and V10 to V50 of heart were analyzed with respect to MHD and AREA for dosimetric parameters using linear and quadratic fit. The treatment parameters calculated by MHD and segments using 2D radiographs were within 2% of the actual dosimetric parameters computed from the 3D planning system. The MHD and AREA vs Dmean, V10, V20, V30 and V50 showed very good correlation with linear model (R2 >0.91); however the correlation was significantly better with quadratic model (R2 >0.92). The analysis of the dosimetric error with our linear and quadratic model is remarkable within <3% error for most cases. The proposed mathematical model for the cardiac dose estimation is accurate within ±3% using a radiograph without CT data. This provides avenues for patient pooling in future studies related to radiation dose and cardiac toxicity. These results will help in estimating cardiac dose analysis accurately from previous studies as well as in centers still using 2D planning. The evidence of cardiac risk following radiotherapy continues to be one of the important considerations for the management of left-sided breast cancer patients. One of the problem in the estimation of dose-risk effects is the reconstruction of heart dose for pre-CT treatments. In this study, a simple mathematical model is presented that could estimate cardiac dose within ±3% in left breast cancer treatment from 2D radiograph where CT data do not exist.