Postmastectomy Breast Cancer Research Articles

Impact of Breathing Motion on IMRT (Intensity Modulated Radiation Therapy) of the Chest Wall in Postmastectomy Breast Cancer Patients: A Dosimetric Comparison With 3D Conformal Radiation Therapy

INTRODUCTION: Radiotherapy forms an essential part of breast cancer treatment. The technology of radiotherapy has developed to give very precise dose to target region with sparing of critical organs. But irradiation of thorax is always influenced by respiratory motion. The influence of respiratory motion on breast cancer radiotherapy and choice of technology based on this has not been studied in detail. We intend to study the effect of respiration on IMRT and 3D conformal radiotherapy of breast cancer. AIM AND OBJECTIVES: To study the dosimetric effect of respiratory motion on intensity modulated radiotherapy to the chest wall in patients with carcinoma breast and compare it with the respiratory motion effect on 3D conformal tangents based plan. MATERIALS AND METHODS: The respiratory parameters of 10 study participants and their dosimetric data on target coverage and dose to organs at risk with IMRT (intensity modulated radiotherapy) and 3D CRT (3D conformal radiotherapy) plans in free breathing, normal inspiration and normal expiration were compared and analysed. RESULTS: Respiratory motion resulted in a significant fall in target coverage (V95) with IMRT when compared to 3D-DRT to chest wall (p=0.007&0.002 vs. 0.174&0.063 with inspiration and expiration respectively) by about 4-5%. Dose inhomogeneity increased in the target volume with respiration, and its minimal dose was decreased by 28% with IMRT in comparison to 14% with 3D-CRT. An analysis of the impact of chest wall movement during IMRT demonstrated that respiration increased the volume of target receiving high radiation dose (11.79% & 20.07% in inspiration and expiration respectively). Evaluation of the dose to organs at risk revealed that there was an overall increasein dose with respiration in IMRT more than 3D-CRT. However, the mean cardiac dose in left sided breast cancer patients crossed the limit of V25 0.68 L and chest wall expansion of >0.5 cm had a poor target coverage with respiration in IMRT (though not significant statistically). The difference in target under-coverage between 3D CRT and IMRT was 11.2% & 5.08% with inspiration and expiration respectively, when tidal volume was >0.68 L. CONCLUSIONS: The dose delivered to target volume is dependent on respiratory movement of chest wall in IMRT technique. It is important to consider the respiratory parameters of a patient prior to choosing the technique of post- mastectomy radiotherapy.

SU-E-T-632: A Dosimetric Comparison of the 3D-CRT Planning of Chest Wall in Post-Mastectomy Breast Cancer Patients, with and Without Breast Board Setup

Purpose: Breast boards are used in breast radiation which increases normal lung and heart doses, when supraclavicular field is included. Therefore, in this study through dose volume histogram (DVHs), lung and heart doses comparison was done between two different setups i.e. with and without breast board, for the treatment of left chest wall and supraclavicular fossa in postmastectomy left breast cancer. Methods: In this study, CT-Simulation scans of ten breast cancer patients were done with and without breast board, at Shifa International Hospitals Islamabad, to investigate the differences between the two different setups of the irradiation of left chest wall in terms of lung and heart doses. For immobilization, support under the neck, shoulders and arms was used. Precise PLAN 2.15 treatment planning system (TPS) was used for 3D-CRT planning. The total prescribed dose for both the plans was 5000 cGy/25 fractions. The chest wall was treated with a pair of tangential photon fields and the upper supraclavicular nodal regions were treated with an anterior photon field. A mono-isocentric technique was used to match the tangential fields with the anterior field at the isocentre. The dose volume histogram was used to compare the doses of heart and ipsilateral lung. Results:more » Both the plans of each patient were generated and compared. DVH results showed that for the same PTV dose coverage, plans without breast board resulted in a reduction of lung and heart doses compared with the plans with breast board. There was significant reductions in V20, V<25 and mean doses for lung and V<9 and mean doses for heart. Conclusion: In comparison of both the plans, setup without breast board significantly reduced the dose-volume of the ipsilateral lung and heart in left chest wall patients. Waived registration request has been submitted.« less

Clinical Activity of Adjuvant Cytokine-Induced Killer Cell Immunotherapy in Patients with Post-Mastectomy Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a high risk form of this disease, even after surgery, due to the absence of targets for hormone treatment and anti-Her-2 therapy. Chemotherapy is the main therapeutic strategy for such patients with breast cancer, although the outcome is often unsatisfactory. Thus, the development of combination adjuvant therapies is essential for improved prognosis in patients with TNBC. In this study, we investigated the efficacy of a sequential combination of cytokine-induced killer cell (CIK) infusion and chemotherapy for patients with post-mastectomy TNBC. From 2008 to 2012, 90 patients with post-mastectomy TNBC were included in this retrospective study: 45 cases received chemotherapy alone or with sequential radiotherapy; a further 45 cases received chemotherapy with/without radiotherapy and sequential CIK infusion. Survival analysis showed significantly higher disease-free survival (DFS) and overall survival (OS) rates in the CIK treatment group compared with the control group (P = 0.0382, P = 0.0046, respectively; log-rank test). Multivariate survival analysis showed that CIK adjuvant treatment was an independent prognostic factor for OS of patients with TNBC. In subgroup analyses, CIK adjuvant treatment significantly increased the DFS rate of patients with pathologic grade 3, and significantly increased the OS rate of patients in N1, N2, N3, IIB, III TNM (tumor-node-metastasis) stages, and with pathologic grade 3. These data indicate that adjuvant CIK treatment combined with chemotherapy is an effective therapeutic strategy to prevent disease recurrence and prolong survival of patients with TNBC, particularly those with lymph node metastasis, advanced TNM stage, and poor pathologic grade. Clin Cancer Res; 20(11); 3003-11. ©2014 AACR.

Systematic review on the patient-reported outcomes of tissue-expander/implant vs autologous abdominal tissue breast reconstruction in postmastectomy breast cancer patients.

Systematic review on the patient-reported outcomes of tissue-expander/implant vs autologous abdominal tissue breast reconstruction in postmastectomy breast cancer patients.

Safety of Tissue Expander/Implant versus Autologous Abdominal Tissue Breast Reconstruction in Postmastectomy Breast Cancer Patients

Breast reconstruction after mastectomy for breast cancer should be informed by evidence-based knowledge, such as complication rates. The authors compared the safety of tissue expander/implant reconstruction with that of autologous abdominal tissue reconstruction. A systematic literature review identified peer-reviewed studies published from January of 2000 to October of 2012 that compared tissue expander/implant against autologous abdominal tissue reconstruction in the MEDLINE, EMBASE, Cochrane Library, PubMed, and ProQuest Dissertations and Theses databases. Two reviewers independently screened all reports and selected the relevant articles using specific inclusion criteria. Data were extracted from the relevant articles using a standardized abstraction form. Fourteen observational studies were identified that included more than 3000 reconstructed breasts. Significant differences were found between these two approaches. The relative risk associated with reconstructive failure favored autologous abdominal tissue (relative risk, 0.14; 95 percent CI, 0.06 to 0.32; I = 0 percent). Surgical-site infection was significantly lower in autologous abdominal tissue reconstruction compared with tissue expander/implant (relative risk, 0.37; 95 percent CI, 0.25 to 0.55; I = 0 percent), although skin or flap necrosis was higher in autologous abdominal tissue reconstruction compared with tissue expander/implant (relative risk, 2.79; 95 percent CI, 1.87 to 4.17). Studies were of low to moderate quality according to the Newcastle-Ottawa scale. This study suggests that tissue expander/implant reconstruction has a higher risk of reconstructive failure and surgical-site infection compared with autologous abdominal tissue reconstruction. With the lack of long-term safety studies on different approaches to breast reconstruction, additional long-term comparative studies are needed to support evidence-based decision-making. Therapeutic, III.

Volume-Based Parameters of 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Improve Disease Recurrence Prediction in Postmastectomy Breast Cancer Patients With 1 to 3 Positive Axillary Lymph Nodes

To determine whether volume-based parameters on pretreatment (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in breast cancer patients treated with mastectomy without adjuvant radiation therapy are predictive of recurrence. We retrospectively analyzed 93 patients with 1 to 3 positive axillary nodes after surgery, who were studied with (18)F-fluorodeoxyglucose positron emission tomography/computed tomography for initial staging. We evaluated the relationship between positron emission tomography parameters, including the maximum standardized uptake value, metabolic tumor volume (MTV), and total lesion glycolysis (TLG), and clinical outcomes. The median follow-up duration was 45 months. Recurrence was observed in 11 patients. Metabolic tumor volume and TLG were significantly related to tumor size, number of involved nodes, nodal ratio, nuclear grade, estrogen receptor (ER) status, and triple negativity (TN) (all P values were <.05). In receiver operating characteristic curve analysis, MTV and TLG showed better predictive performance than tumor size, ER status, or TN (area under the curve: 0.85, 0.86, 0.79, 0.74, and 0.74, respectively). On multivariate analysis, MTV was an independent prognostic factor of locoregional recurrence-free survival (hazard ratio 34.42, 95% confidence interval 3.94-882.71, P=.0008) and disease-free survival (DFS) (hazard ratio 13.92, 95% confidence interval 2.65-103.78, P=.0018). The 3-year DFS rate was 93.8% for the lower MTV group (<53.1; n=85) and 25.0% for the higher MTV group (≥53.1; n=8; P<.0001, log-rank test). The 3-year DFS rate for patients with both ER-positive status and MTV<53.1 was 98.2%; and for those with ER-negative status and MTV≥53.1 it was 25.0% (P<.0001). Volume-based parameters improve recurrence prediction in postmastectomy breast cancer patients with 1 to 3 positive nodes. The addition of MTV to ER status or TN has potential benefits to identify a subgroup at higher risk for recurrence.

Survey on Radiation Practice Patterns Among US Radiation Oncologists for Postmastectomy Breast Cancer and Reconstruction

Survey on Radiation Practice Patterns Among US Radiation Oncologists for Postmastectomy Breast Cancer and Reconstruction

Long-term Survival Outcomes Following Internal Mammary Node Irradiation in Stage II-III Breast Cancer: Results of a Large Retrospective Study With 12-Year Follow-up

To examine the effect of internal mammary node irradiation (IMNI) on disease-free survival (DFS) and overall survival (OS) in breast cancer patients treated with modified radical mastectomy and postoperative radiation therapy. Between 1994 and 2002, 396 patients with stage II-III breast cancer were treated with postmastectomy radiation therapy with (n=197) or without (n=199) IMNI. Patients who received neoadjuvant chemotherapy were excluded. IMNI was administered at the clinical discretion of the treating physician. Median RT dose was 50.4 Gy (range, 45.0-59.4 Gy) in 28 fractions, with inclusion of the supraclavicular fossa in 96% of patients. Adjuvant chemotherapy was administered to 99.7% of the patients and endocrine therapy to 53%. The median follow-up was 149 months (range, 124-202). IMNI patients had more advanced nodal stage and non-high grade tumors than those without IMNI (P<.001). Otherwise, disease and treatment characteristics were well balanced. The 10-year DFS with and without IMNI was 65% and 57%, respectively (P=.05). Multivariate analysis demonstrated that IMNI was an independent, positive predictor of DFS (hazard ratio [HR], 0.70; P=.02). Benefits of IMNI in DFS were seen most apparently in N2 patients (HR, 0.44; 95% confidence interval [CI], 0.26-0.74) and inner/central tumors (HR, 0.55; 95% CI, 0.34-0.90). The 10-year OS with and without IMNI was 72% and 66%, respectively (P=.62). The 10-year DFS and OS were 61%, and 69%, respectively. Internal mammary node irradiation significantly improved DFS in postmastectomy breast cancer patients. Pending long-term results from randomized trials, treatment of internal mammary nodes should be considered in postmastectomy radiation therapy.

Volume-based parameters on FDG-PET/CT as early predictors of disease recurrence in postmastectomy breast cancer patients with one to three positive axillary lymph nodes without adjuvant radiotherapy.

1124 Background: The indication for postmastectomy radiotherapy (PMRT) in patients with 1-3 lymph node metastases in the axilla have been controversial, despite the recommendation that PMRT should be applied. In the current study, we focused our study on volume-based parameters of pretreatment FDG-PET/CT, with the aim of investigating a measurement that could help identify high-risk populations for recurrence. Methods: We retrospectively analyzed 88 patients of breast cancer treated with modified radical mastectomy and were found to have 1-3 metastatic axillary lymph nodes between 2006 and 2010. All of them were studied with FDG-PET/CT for initial staging. We evaluated the relationship between clinicopathologic factors or PET parameters including the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and recurrence. MTV and TLG of the primary tumor and metastatic lymph node were measured by using semi-automatically delineated volume of interest (VOI) with an isocontour threshold of 40 % of the SUVmax. The optimal cutoffs of PET parameters were determined by ROC curve analysis. Results: The median follow up duration was 39 months. Median MTV was 21.1and median TLG was 42.7. Recurrence was observed in 10 patients. The area under the ROC curve of MTV and TLG for DFS was 0.82 and 0.85, respectively. In Cox univariate analysis, estrogen receptor status (HR = 6.8, p = 0.003), triple negativity (HR = 10.4, p = 0.0008), SUVmax (HR = 71.1, p = 0.001), MTV (HR = 130.3, p &lt; 0.0001), and TLG (HR = 234.1, p = 0.0001) were significantly related to disease free survival (DFS). The estimated 3-year DFS rates were 96.4 % for the lower MTV group (&lt; 31.8) and 71.4% for the higher MTV group (≥ 31.8, p = 0.0005). The estimated 3-year DFS rates were 95.8 % for the lower TLG group (&lt; 109.6) and 50.0 % for the higher TLG group (≥ 109.6, p &lt; 0.0001). On multivariate analysis, TLG was an independent prognostic factor of DFS (HR = 8.5, p = 0.005). Conclusions: Volume-based parameters on FDG-PET/CT were significant predictors of DFS in postmastectomy breast cancer patients with 1-3 metastatic axillary lymph nodes.

314 - Moving From 2D to 3D-CRT Planning of Chest Wall for Postmastectomy Breast Cancer Patients: Mansoura University Experience

ABSTRACT Background This study evaluates the dose distribution of the wedged tangential beam three-dimensionally planned conformal radiotherapy (3D-CRT) compared to the previously used (5 years ago) two-dimensionally(2D) planned radiotherapy of the chest wall for postmastectomy breast cancer patients in Clinical Oncology and Nuclear Medicine Department - Mansoura University. Patients and methods Thirty six breast cancer patients were randomized for planning by both the standard 3D-CRT and 2D-RT techniques for radiotherapy of the chest wall. Dose-volume histograms were carried out by the 3D treatment planning system. They were assessed for the PTV and organs at risk. The total dose was 50 Gy in 25 fractions. Results The three–dimensionally planned conformal radiotherapy showed a significantly better homogeneity index of the PTV (chest wall). The ipsilateral mean lung dose was significantly reduced with the tangential beam 3D-CRT plans with an average of 24.6% (1217 cGy versus 1614 cGy). For the left sided breast cancer patients, the mean heart dose was also reduced by an average of 48.6% (718 cGy versus 1398 cGy). Conclusions The tangential beam 3D-CRT planning demonstrated a significantly better homogeneity index for the PTV of the postmastectomy breast cancer patients with a statistically significant reduction in the mean doses of the ipsilateral lung and the heart for the left –sided breast cancer patients. Disclosure All authors have declared no conflicts of interest.

71P Study of Dose Distribution of Tangential Beam Intensity Moduleted Radiotherapy Compared to Tangential Beam 3D Conformal Radiotherapy of Chest Wall in Post Mastectomy Breast Cancer Patients

Aims and objectivesTo compare the dose distribution of tangential beam intensity modulated radiotherapy with tangential beam 3Dconformal radiotherapy of chest wall in post mastectomy breast cancer patients. MethodsPatients coming to department of radiotherapy, SMS Medical College were selected for the study for 20 subsequent postmastectomy breast cancer patients tangential beam IMRT and tangential beam 3D-CRT plans were generated for the radiotherapy of the chest wall. The prescribed dose was 50 Gy in 25 fractions. Dose-volume histograms were evaluated for the PTV and organs at risk. Parameters of the dose distribution were compared using the Wilcoxon matched pairs test. ResultsTangential beam IMRT statistically significantly reduced the ipsilateral mean lung dose by an average of 21% (1129 cGy versus 1437 cGy). In all patients treated on the left side, the heart volume encompassed by the 70% isodose line (V70%; 35 Gy) was reduced by an average of 43% (5.7% versus 10.6%), and the mean heart dose by an average of 20% (704 cGy versus 877 cGy). The PTV showed a significantly better conformity index with IMRT; the homogeneity index was not significantly different. ConclusionsTangential beam IMRT significantly reduced the dose-volume of the ipsilateral lung and heart in unselected postmastectomy breast cancer patients. DisclosureAll authors have declared no conflicts of interest.

Pilates for Breast Cancer Survivors

Pilates has been advocated for rehabilitation of breast cancer survivors despite little scientific evidence. The authors of this article have examined the feasibility of a Pilates program in postmastectomy breast cancer survivors and the impact on physical and psychological parameters. Fifteen breast cancer survivors were recruited in a one-arm study of 12 weeks of Pilates exercises. The authors assessed recruitment, adherence, and attrition, and measured changes in shoulder and neck range of motion, posture, height, arm volume, quality of life, mood, and body image from pre- to postintervention. Of 26 eligible patients, 15 enrolled, 13 completed the study, and 10 performed more than 50% of the recommended sessions. Statistically significant improvements emerged for shoulder abduction and internal rotation on the affected side, neck rotation toward the unaffected side, and neck flexion. The affected side arm volume and the interlimb volume discrepancy increased. Significant improvements were reported in quality of life, mood, and body image. The improvements in physical and psychological outcomes are promising and deserve further evaluation in a randomized, controlled study. The increase in affected arm volume also warrants additional investigation.

Hypofractionation in post-mastectomy breast cancer patients: seven-year follow-up

To compare three fractionation schedules in post-mastectomy patients treated with radiotherapy as regard acute and early late effects as well as local recurrence rates. One hundred and seven breast cancer patients treated with modified radical mastectomy and adjuvant radiotherapy±adjuvant systemic treatments between November 2001 and July 2004 were enrolled in this study. Patients were categorized into three groups. Group A (41 patients) received conventional fractionation 50 Gy over 25 fractions. Group B (36 patients) received other fractionation regimen 45 Gy over 17 fractions. Group C (30 patients) received 40 Gy over 15 fractions. The median follow-up period was 23 months. There has been no statistical significant difference in local control (P=0.88), pain (P=0.98), telangectasis (P=0.23), fibrosis (P=0.13), arm oedema (P=0.96) or pigmentation (P=0.80) between the three groups. GII-III Erythema was significantly higher in the two hypofractionation arms compared to the control arm (P=0.001). Although acute skin reactions were higher in the hypofractionated arms, there was no significant difference in the local recurrence rates or late radiation effects. A national randomized multicentre study is recommended to explore this further.

Fatigue in breast cancer patients on adjuvant treatment: Course and prevalence

Introduction:Fatigue is a major complain in breast cancer patients and survivors. Patterns and degree varies with schedule and type of the treatment. Different co-factors may aggravate fatigue. Multimodal approach is helpful in managing fatigue.Aim:To quantify prevalence, course and degree of fatigue in breast cancer patients on adjuvant treatment and effectiveness of different management approach.Materials and Methods:One Hundred and ten post-mastectomy breast cancer patients (Stage I to Stage III) were assessed. Patients on chemotherapy were assessed one week before, day after chemotherapy and two weeks later in every cycle. Patients on External Beam Radiation Therapy (EBRT) were assessed one week before and every week during radiation. Assessment was continued on second and fourth week of follow up. Functional Assessment of Chronic Illness Therapy - Fatigue subscale (FACIT-F) was used for assessment. Significant cofactors were also searched for.Results:Eighty four percent patients experienced fatigue. Fatigue was more prevalent during chemotherapy (91%) than EBRT (77%). Patients on Chemotherapy exhibit peak fatigue day after Chemotherapy and decreased level until the next cycle. Significant increase of fatigue was seen only in first cycle. Patient on EBRT had gradually increased fatigue during the course of treatment. Lower degree of fatigue was present in post treatment period. Anemia was a significant cofactor causing fatigue (P < 0.05). Blood Transfusion improved fatigue scores.Conclusion:Fatigue increases during chemotherapy and or EBRT. Different intervention strategies are needed to address the issue.

P1-11-05: Investigation of Epidemiological Factors as Barriers to Indicated Radiation Therapy in Post-Mastectomy Breast Cancer Patients in South Carolina.

Abstract Purpose: Post-mastectomy radiation therapy (PMRT) has been shown to provide improved locoregional control and overall survival in intermediate and high-risk breast cancer patients1,2. To investigate the frequency of utilization and potential barriers to receipt of adjuvant PMRT in South Carolina, an analysis of the S.C. Cancer Registry (SCCR) database was undertaken. Methods: Epidemiological factors such as age, race, and geographic distance from a radiation therapy facility were analyzed as potential predictors of whether patients received the indicated radiotherapy. Post-mastectomy breast cancer patients (n=1080) recorded in the SCCR from 2006–2008 were stratified as low (Tis/T1, N0) (43%), intermediate (T1/T2, N1) (27%), or high (T3/T4, N2/N3) (30%) risk. Logistic regression models were used to predict receipt of adjuvant radiotherapy based on factors such as race, age, and geographical distance from radiation treatment facility. Results: Adjuvant PMRT was received in 4% (19/469) of low risk patients, 23% (67/288) of intermediate risk patients, and 44% (141/323) of high risk patients. In both intermediate and high risk groups, older patients were less likely to receive PMRT. The odds of receiving PMRT decreased by 3% (OR= 1.03; 95% CI: 1.01−1.05; p=0.01) and 2% (OR=1.02; 95% CI: 1.002−1.035; p=0.03) per year in the intermediate and high risk groups, respectively. Race and distance from treatment facility were not predictive of receipt of PMRT in high risk patients. Conclusion: Utilization of adjuvant PMRT in intermediate and high risk breast cancer patients in South Carolina is low, despite the evidence that it confers a survival benefit in both premenopausal and postmenopausal women. Of the patient-related factors analyzed, only age predicted lower odds of receiving radiotherapy in both the intermediate and high risk group. In high risk patients of advanced age (&amp;gt;70), breast cancer continues to be a major cause of mortality which can be improved by radiotherapy3. Future educational efforts should focus on addressing patient and physician bias against radiotherapy based on patient age. Further study is needed to identify socio-economic-, physician- and health system- related factors that maybe impacting the underutilization of PMRT in South Carolina.

Tangential beam IMRT versus tangential beam 3D-CRT of the chest wall in postmastectomy breast cancer patients: A dosimetric comparison

BackgroundThis study evaluates the dose distribution of reversed planned tangential beam intensity modulated radiotherapy (IMRT) compared to standard wedged tangential beam three-dimensionally planned conformal radiotherapy (3D-CRT) of the chest wall in unselected postmastectomy breast cancer patientsMethodsFor 20 unselected subsequent postmastectomy breast cancer patients tangential beam IMRT and tangential beam 3D-CRT plans were generated for the radiotherapy of the chest wall. The prescribed dose was 50 Gy in 25 fractions. Dose-volume histograms were evaluated for the PTV and organs at risk. Parameters of the dose distribution were compared using the Wilcoxon matched pairs test.ResultsTangential beam IMRT statistically significantly reduced the ipsilateral mean lung dose by an average of 21% (1129 cGy versus 1437 cGy). In all patients treated on the left side, the heart volume encompassed by the 70% isodose line (V70%; 35 Gy) was reduced by an average of 43% (5.7% versus 10.6%), and the mean heart dose by an average of 20% (704 cGy versus 877 cGy). The PTV showed a significantly better conformity index with IMRT; the homogeneity index was not significantly different.ConclusionsTangential beam IMRT significantly reduced the dose-volume of the ipsilateral lung and heart in unselected postmastectomy breast cancer patients.

Breast cancer after bilateral risk-reducing mastectomy

This study aims to evaluate the incidence of breast cancer after risk-reducing mastectomy (RRM) in healthy BRCA mutation carriers. This study is a long-term follow-up of 307 BRCA mutation carriers of whom 96 chose RRM. None of the study participants had a previous history of breast or ovarian cancer nor had they undergone RRM or risk-reducing bilateral salpingo-oophorectomy (BSO) prior to the time of BRCA testing. The annual incidence of post-mastectomy breast cancer was 0.8% compared with 1.7% in the non-operated group. Implications of these findings in relation to genetic counseling and future management are discussed.

Incidental Radiation Dose to Presumed Uninvolved Internal Mammary Lymph Nodes in Breast Cancer Patients Receiving Post-mastectomy Irradiation Adjuvant Therapy

Routine prophylactic treatment of uninvolved internal mammary nodes (IMN) in breast cancer patients requiring post-mastectomy radiation therapy (PMRT) is controversial. While randomized trials demonstrating survival benefit of PMRT often included IMNs, doing so increases the normal tissue doses, especially the heart dose, which is associated with an increase in radiation induced morbidity/mortality. The purpose of this study was to measure the incidental radiation dose to the internal mammary lymph nodes (IMN) not included in the planning target volume (PTV) in women with breast cancer receiving PMRT irradiation. This study was a retrospective, IRB approved protocol using CT-based 3D conformal (3D CRT) treatment plans. Thirty-three consecutive patients were included in the analysis: 17 left side and 16 right side patients. All patients received standard 3D CRT chest wall tangent fields and matched supraclavicular (SCV) fields. All plans were prescribed a total dose of 50 Gy in 25 fractions to the chest wall and 46 Gy in 23 fractions to the SCV field. The IMN chain was not intentionally included in the target volume. For purposes of this study, IMN vessels were contoured following the RTOG atlas, utilizing original CT simulation images. A 7 mm PTV expansion was added to the IMN contours. Pinnacle treatment planning algorithm was used to quantify the radiation dose volume histograms. The percent volume of IMN PTV receiving 100% of the prescribed dose (50Gy) for all patients was 24% (range, 0-73%, SD 23.9). The percent volume of IMN PTV receiving 95% of the prescribed dose (45 Gy) for all patients was 34% (range, 0.6-92%, SD 27.3). The percent volume of IMN PTV receiving 90% of the prescribed dose (40 Gy) for all patients was 39.5% (range, 1-97%, SD 28.8). The mean IMN dose for all patients was 23.4 Gy (range, 3.5-52.9, SD 15.8). The IMN absolute dose range for all patients was 5.09- 51.05 Gy. The volume of lung receiving 20 Gy (V20) for left sided and right sided were 13.8%, (range, 7.23-18.5%, SD 2.8%) and 15.5% (range, 8.9-28.4%, SD 5.1%), respectively. The volume of heart receiving 30 Gy (V30) for left sided and right sided were 4.2% (range, 0.05-13.3%, SD 3.8%) and 0.0003% (range, 0-0.4%, SD 0.001%) respectively. The results of this study suggest that the incidental dose to the IMN nodes does not achieve therapeutic levels in post mastectomy breast cancer patients treated with standard 3D CRT chest wall irradiation. If risk factors for microscopic involvement are present, IMNs must be specifically included in target volumes in order to be adequately treated.

Planning tools for modulated electron radiotherapy

To develop tools to plan modulated electron radiotherapy (MERT) and to compare the MERT plans to conventional or intensity modulated radiotherapy (IMRT) treatment plans. Monte Carlo dose calculations of electron fields shaped with the inherent photon multileaf collimators (MLCs) were investigated in this study. Treatment plans for four postmastectomy breast cancer patients were generated using MERT. The distances from the patient skin surfaces to the distal planning target volume surfaces were computed along the beam axis direction to determine the physical depth. Electron beam energies were selected to provide target coverage at these depths and energy bins were generated. A custom built MERT treatment planning graphical user interface (MERTgui) was used to shape the electron bins into deliverable electron segments. Monte Carlo dose distribution simulations were performed using the MLC-defined segments generated from the MERTgui. A custom built superposition gui was used to combine doses for each segment using relative weights and final MERT treatment plans were compared to the conventional or IMRT treatment plans. In addition, a demonstration of combined MERT and IMRT treatment plans was performed. The MERT treatment plans provided acceptable target organ coverage in all cases. Relative to 3D conventional or IMRT treatment plans, the MERT plans predicted lower heart doses in all cases; average of the heart D20 of all plans was reduced from 14.1 to 3.3 Gy. The contralateral breast and contralateral lung doses decreased substantially with MERT planning compared to IMRT (on average, contralateral breast heart D20 was reduced from 8.7 to 0.7 Gy and contralateral lung D20 was reduced from 8.4 to 1.2 Gy with MERT). Ipsilateral lung D20 was lower with MERT than with the conventional plans (44.6 vs 29.2 Gy with MERT), but greater when compared against IMRT treatment plans (25.4 vs 28.9 Gy with MERT). A MERT and IMRT combination plan was generated to benefit from the complementary advantages of MERT and IMRT, resulting in satisfactory target coverage and reduced organ at risk doses. MERT tools can facilitate treatment planning and provide plans for treatment of shallow targets such as the postmastectomy chest wall.

Effect of Photon Energy on Superficial Dose in the Treatment of Breast Cancer with Tangent Fields

The treatment volume for post-mastectomy breast cancer patients treated with radiation therapy includes the entire breast, and in particular the skin. In patients with larger breasts, high energy photons are often used achieve desired levels of dose homogeneity. However, this may result in reduced dose to the more superficial aspects of the breast (i.e., the subcutaneous tissue) if a beam spoiler is not used. This study was performed to evaluate the effects of photon energy on superficial dose in breast cancer patients treated with external beam radiation.