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Effect of Regional Nodal Irradiation on Overall Survival in Patients With High-risk Invasive Breast Cancer: A National Cancer Data Base Analysis
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International Journal of Radiation Oncology Biology Physics
for reirradiation to the postmastectomy chest wall and regional lymph nodes (LN) for a primary (N Z 1) or recurrent (N Z 16) breast cancer diagnosis. Indications for inclusion of LN included lymph node positive disease (N Z 9) or inability to surgically assess the axilla, pNX (N Z 8). Seven patients had immediate reconstruction prior to initiation of PT. Prior RT characteristics include the following: 40 Gy to a mantle field for Hodgkin Lymphoma (N Z 1), RT to the intact breast for initial breast cancer diagnosis (N Z 15), and partial breast RT (N Z 1). Median dose of the initial RT course was 60 Gy (34-70 Gy). Median time interval between courses of RT was 12.1 years (3-28.4 years). Reirradiation was performed with uniform scanning PT. Chest wall and LN contours were drawn according to the RTOG consensus guidelines with the exception of editing the chest wall at the superficial aspect of the ribs and intercostals. Median PT dose was 50.11 (45.1-76.31) cobalt gray equivalent (CGE). 3 patients had gross disease at PT initiation. Patients were evaluated clinically and toxicity was assessed prospectively per CTCAE v. 4.0 at baseline, weekly during PT, 2 weeks, and 4 weeks following PT and then every 6 months. Results: Median follow-up (FU) was 8 months (2-39 months). All patients had locoregional control at last FU. One woman developed distant metastases 17 months following PT. Acute skin toxicity occurred in all patients; grade 1 (N Z 4), grade 2 (N Z 12) and grade 3 (N Z 1). Grade 1 esophagitis occurred in 11 patients; grade 2 in 4 patients. Grade 2 chest wall pain occurred in 6 patients; grade 3 in 1 patient. The patient with grade 3 skin toxicity and chest wall pain had diffuse painful moist desquamation which worsened and peaked 2 weeks postPT. She had a long standing history of allergies to multiple skin creams. The skin reaction and pain resolved when she stopped using her skin care regimen. One woman experienced rib fracture 18 months post-PT, receiving a cumulative dose of 111 CGE between the 2 courses of RT. Pneumonitis requiring steroid treatment occurred in 1 woman 7 months post-PT. 2 women reported clinical lymphedema at last follow-up. 1 woman reported a non-healing wound at last follow-up. This patient started PT prior to complete wound healing after surgery due to the development of dermal lymphatic gross recurrence within 2 weeks following surgery. Conclusion: Reirradiation with PT in breast cancer patients appears to have acceptable acute toxicity. Longer FU is needed. Author Disclosure: L.A. McGee: None. N. Badar: None. Z. Iftekaruddin: None. J.H. Chang: Partnership; Radiation Oncology Consultants, Chicago Proton Therapy Investments, Elk Grove Radiosurgery, Illinois CyberKnife. V. Gondi: Partnership; Radiation Oncology Consultants. S. Schmidt: None. D. Kaplan: None. S. Gans: None. M. Pankuch: None. W.F. Hartsell: Partnership; Chicago Proton Therapy Investments, Radiation Oncology Consultants, Elk Grove Radiosurgery Incorporation, Illinois CyberKnife.
Results: Forty patients with BC who had surgery for cosmetic breast implant were analyzed. The mean time from that cosmetic surgery to oncologic surgery was 11 years (2-42 years). Before RT 28 patients had one aesthetic surgery, but 11 patients had 2 previous surgeries and 1 patient up to 3. The implant material was: silicone 60% and 40% saline. The location was 30 retro glandular implants, and 7 retro pectoral, and 3 unknown. The mean follow-up was 35 months (24-102), the mean age of BC diagnosis was 54 years (35-76), Left side 23, 3DCRT 37, Stages 0: 12.5% I: 67.5% II: 20%.8 smokers and alcoholic 2, no diabetic patients. Acute radiation toxicity RTOG scale was I Z 29, II Z 10, III Z 1. The local recurrence rate was 5%. A replacement of implant after RT was required in 5 patients. Prosthetic contracture before RT was analyzed with Baker classification I Z 23; II Z 11; III Z 6. Baker III and IV were tested to identify their influence on aesthetics. Age, time since cosmetic surgery, smoking, drinking, prosthetic material, location, RT technique, hormonetherapy, and acute toxicity were not significant; however, in patients who had more than one previous cosmetic surgery a difference was obtained P Z 0.034 assigning RR 4.67 of worst result according to the number of previous surgeries. The results of Harvard reported by patients and the physicians were: Excellent 19 and 21; Good 12, 9; tolerable 3, 7; Poor 6, 3; respectively. 12 patients reported changing results after RT according to Harvard scale; for the physicians just 9, of them, initially had poor or tolerable results in 8 and 6 respectively. The difference between the observers was not significant P Z 0.3 Conclusion: We found a group of patients 27.5% who had a tendency to capsular contracture previous to RT related to the number of surgeries before treatment. The lower result in Harvard scale after RT reported by patient and physicians was 30% and 22.5% respectively, but this change was 20% and 15% for tolerable and poor results. There was an agreement related to cosmetic outcomes according the physicians and patient. It is important to point out; that only 12.5% of the patients needed an implant replacement for disagreement related to esthetic, most of them are satisfied. Author Disclosure: D. Bejarano: None. M. Picasso: None. K. Rojas ´ . Tavella: None. R. Alva: None. O. Furia: None. J. Criales: None. M.A Chiozza: None. M. Girola: None. M. Andrade Irusta: None. H. Donato: None. M. Filomia: None. L.E. Rafailovici: None.
2121 Cosmesis After Breast Irradiation in Patients With Breast Implants ´ . Tavella, R. Alva, D. Bejarano, M. Picasso, K. Rojas Criales, M.A O. Furia, J. Chiozza, M.J. Girola, M. Andrade Irusta, H. Donato, M. Filomia, and L.E. Rafailovici; Vidt Centro Medico - 21st Century Oncology, Buenos Aires, Argentina Purpose/Objective(s): To evaluate the cosmetic results in patients with breast implants treated with radiation therapy (RT) for BC, and analyze factors associated with low cosmetic results considering the assessment of the physicians and patient. Materials/Methods: We selected patients with breast implants and diagnosed BC who received RT. Capsular contracture was evaluated by Baker scale before and after RT and at 3, 6, 12, and 24 months. To objectify the cosmesis, patient and two radiation oncologists were asked to classify results by Harvard scale. To investigate factors that may influence the capsular contracture and cosmetics, T test, chi-square, and Wilcoxon signed-rank were analyzed.
2122 Effect of Regional Nodal Irradiation on Overall Survival in Patients With High-risk Invasive Breast Cancer: A National Cancer Data Base Analysis A.C. Moreno,1 H. Lin,1 I. Bedrosian,1 B.D. Smith,2 G. Babiera,1 M.C. Stauder,1 T.A. Buchholz,3 W.A. Woodward,1 Y. Shen,1 and S.F. Shaitelman1; 1MD Anderson Cancer Center, Houston, TX, 2MD Anderson, Houston, TX, 3The University of Texas MD Anderson Cancer Center, Houston, TX Purpose/Objective(s): The role of regional nodal irradiation (RNI) in specific subgroups of breast cancer patients remains controversial. Using the National Cancer Data Base (NCDB), we aimed to utilize population level data to validate published clinical trial data examining the effect of adding RNI to whole breast irradiation (WBI) on overall survival (OS) of patients with node-positive (pN1-3) or high-risk node-negative (pN0) breast cancer treated with breast conserving surgery (BCS) and adjuvant systemic therapy. Materials/Methods: Women with pN1-3 or high-risk pN0 breast cancer treated with BCS followed by adjuvant systemic therapy and radiation therapy to the whole breast with or without RNI in the United States from 2004 to 2012 were analyzed. High-risk features for pN0 disease included tumor size 5 cm, or tumors measuring 2-4.9 cm that were high grade or hormone receptor negative. Patients with pN1-3 had to undergo a complete axillary lymph node dissection (ALND). A propensity score matched analysis was performed, the Kaplan-Meier method was used to estimate the 5-year OS for the non-matched and matched cohorts, and comparisons were made using log-rank or stratified log-rank tests (for the matched
Volume 96 Number 2S Supplement 2016 cohort) and Cox proportional hazard (PH) regression model or double robust estimation under Cox PH model (for the matched cohort). Subset analyses were performed using matched cohort patients with either pN1-3 or high-risk pN0 disease. Results: A total of 23,567 patients met the criteria; 6,920 (29%) received RNI and 16,647 (71%) received WBI. The use of RNI increased from 25.2% in 2004 to 32.2% in 2012 in the non-matched cohort. In the non-matched cohort, the 5-year OS was 90.8% with RNI and 92.6% with WBI only (P<.0001), whereas in the matched cohort (n Z 10,922), 5-year OS was 92% with RNI and 91.9% with WBI (P Z 0.45). For the matched cohort, the difference in OS remained insignificant in the multivariate model after adjusting for the matching factors (HR 1.02, 95% CI 0.89-1.17). On subset analysis, RNI was not associated with significant improvement of OS in patients with pN1-3 (HR 0.98, 95% CI 0.85-1.13) or high-risk pN0 (HR 1.61, 95% CI 0.972.67) disease. Conclusion: The utilization of RNI in the treatment of high-risk invasive breast cancer has been slowly increasing over time. The largest retrospective study to date, our findings suggest that in women with nodepositive or high-risk node-negative breast cancer who undergo BCS followed by adjuvant systemic therapy, the addition of RNI to whole breast irradiation is not significantly associated with improved overall survival, confirming the findings of the NCIC MA-20 randomized clinical trial. Author Disclosure: A.C. Moreno: None. H. Lin: None. I. Bedrosian: None. B.D. Smith: None. G. Babiera: None. M.C. Stauder: None. T.A. Buchholz: None. W.A. Woodward: None. Y. Shen: None. S.F. Shaitelman: None.
2123 Do Women Who Died of Cardiac Disease Within 10 Years of Breast or Chest Wall Radiation Therapy Violate the “QUANTEC” Cardiac Dose-Volume Histogram Guidelines? L.E. Beaton,1,2 A. Bergman,1,2 A. Nichol,1,2 L. Weir,1,2 and S. Tyldesley1,2; 1BC Cancer Agency, Vancouver, BC, Canada, 2 University of British Columbia, Vancouver, BC, Canada Purpose/Objective(s): Breast and chest wall irradiation (RT) increase the risk of cardiac death. This increased risk is presumed to be a result of the incidental exposure of the heart to radiation. Previous studies have focused on mean heart dose as a measure of radiation exposure. In the modern era of CT based radiation therapy planning, international guidelines (“QUANTEC”) state that for partial heart irradiation a “V25 Gy < 10% (2 Gy/fraction) will be associated with a less than 1% probability of cardiac mortality” in long term follow-up after radiation therapy. We therefore set out to establish whether or not women who died of cardiac disease within 10 years of breast or chest wall radiotherapy had radiation therapy plans that violated these guidelines. We also assessed the maximum dose of radiation delivered to the left anterior descending (LAD) coronary artery and cardiac volume parameters in these patients, on the assumption that the LAD is the critical structure for RT induced cardiac events. Materials/Methods: A provincial database was used to identify all women under 80 years of age diagnosed with early stage breast cancer who were treated with adjuvant RT to the breast or chest wall between 2002 and 2006, who died of cardiac disease. The heart and LAD were retrospectively delineated using a peer-reviewed cardiac atlas. A 1cm radial margin was placed around the LAD to create a planning organ at risk volume (PRV). For each dose plan, DVH’s for the heart and LAD were calculated and the V25 compared to the current QUANTEC guidelines. Results: Between RT start date and June 2015, 76 patients died of a cardiovascular event after breast or chest wall RT. 42 of these patients received left-sided irradiation, and 34 right-sided irradiation. For the left sided cases, median time from diagnosis to death was 6.7 years. Later cardiac deaths (more than 9 years after diagnosis) were more common for left-sided cases when compared to right-sided cases (38% vs 24%).Radiation therapy plans were available for 31 of the left-sided
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cases. 11 cases were treated without CT planning. 19 patients received radiation doses of 40-42.56 Gy over 16 fractions, and 12 patients doses of 45-50.4 Gy over 25-28 fractions. The heart V25 did not exceed 10% in any of our 31 left sided cases. Equivalent doses in 2-Gy fractions (EQD2) were calculated from the DVH using a/ b 2 Gy. The average maximum heart dose was 35.6 Gy (SD 16.1). The average maximum dose to the LAD was 26.2 Gy (SD 19.7) and 40.9 Gy (SD 15.6) to the LAD PRV. Conclusion: This study has shown that the QUANTEC guidelines were not violated in our cohort of patients that died of cardiac disease after leftsided breast RT. As only 38% of patients died later than 9 years after radiation therapy it may be that pre-existing cardiac risk factors were a dominant factor for cardiac death as opposed to the effect of RT. It remains unclear as to the exact mechanism of increased cardiac mortality as a result of RT, but radiation to the LAD may be more important than the heart V25 in predicting cardiac mortality. Author Disclosure: L.E. Beaton: None. A. Bergman: None. A. Nichol: Research Grant; Varian Medical Systems. Speaker’s Bureau; Varian Medical Systems. L. Weir: None. S. Tyldesley: None.
2124 Assessment of National Practice Patterns of Radiation Therapy Use after Neoadjuvant Chemotherapy for Breast Cancer C.T. Murphy,1 E. Handorf,1 E.R. Sigurdson,1 S.B. Hayes,1 P. Anderson,2 S. Weiss,1 T. Shaikh,1 J.M. Daly,1 M. Boraas,1 and R.J. Bleicher1; 1Fox Chase Cancer Center, Philadelphia, PA, 2Fox Chase Cancer Center, Philadelphia, PA Purpose/Objective(s): To assess patterns and predictors of radiation therapy (RT) use in women receiving neoadjuvant chemotherapy (NAC) in a national breast cancer registry. Materials/Methods: Using the National Cancer Database, we included women with clinical stage III and clinical node-positive stage II breast cancer, known receptor and HER2 status receiving NAC followed by surgery with a known pathologic stage. Significant differences in RT use were analyzed according to surgery type by using the chi-square test. Significant predictors of RT use were identified on multivariate analysis (MVA) via generalized estimating equations adjusting for age, race, insurance type, facility type, comorbidity score, clinical T- and N-stage, pathologic response, tumor grade, ER/PR status, HER2 status, and surgery type, defined as breast conservation (BCS), mastectomy (Mx), and Mx with reconstruction (MxR). Results: A total of 17567 women were included, with 5344 (30%) treated with BCS and 12223 (70%) treated with Mx, of which 3404 underwent MxR (28% of all Mx patients). A total of 10029 (57%) were clinical T12; 11313 (64%) were clinical N1-3; 7347 (42%) had clinical stage III disease; 10592 (60%) were ER/PR+; 4765 (27%) were HER2+. In the BCS cohort, 56% received breast RT, 34% received breast and regional nodal irradiation (RNI) and 10% did not receive RT. On univariate analysis, RT use did not vary according to clinical T- or N-stage, ER/PR status, or HER2 status. Although RT use did not vary according to pathologic nodal response, RT use was more common with primary tumor pathologic downstaging when compared to stable and progressive disease (91% vs 89% vs 84%, P Z 0.02), but not with upstaging. In the Mx cohort, 20% received chest wall RT, 45% received chest wall + RNI, RT was omitted in 4284 (35%). Mx alone was significantly more common in women with clinical T2 primary tumors (46%), clinical N0 disease (52%), ER/PR(-) disease (41%), and Her-2+ status (36%). RT use did not vary according to primary tumor response, but was more commonly omitted in women with stable (42%) or responsive (31%) nodal disease compared to nodal upstaging (25%), P<0.001. Omission of RT was more common in women undergoing MxR vs Mx alone (42% vs 32%, P<0.001). On MVA, advanced clinical nodal stage was the strongest predictor of RT use after NAC. MxR was more strongly associated with RT omission (OR 0.70, 95% CI 0.63-0.77), than with receptor status, HER2 status, or nodal response. Primary tumor response did not predict for RT use.
International Journal of Radiation Oncology Biology Physics
for reirradiation to the postmastectomy chest wall and regional lymph nodes (LN) for a primary (N Z 1) or recurrent (N Z 16) breast cancer diagnosis. Indications for inclusion of LN included lymph node positive disease (N Z 9) or inability to surgically assess the axilla, pNX (N Z 8). Seven patients had immediate reconstruction prior to initiation of PT. Prior RT characteristics include the following: 40 Gy to a mantle field for Hodgkin Lymphoma (N Z 1), RT to the intact breast for initial breast cancer diagnosis (N Z 15), and partial breast RT (N Z 1). Median dose of the initial RT course was 60 Gy (34-70 Gy). Median time interval between courses of RT was 12.1 years (3-28.4 years). Reirradiation was performed with uniform scanning PT. Chest wall and LN contours were drawn according to the RTOG consensus guidelines with the exception of editing the chest wall at the superficial aspect of the ribs and intercostals. Median PT dose was 50.11 (45.1-76.31) cobalt gray equivalent (CGE). 3 patients had gross disease at PT initiation. Patients were evaluated clinically and toxicity was assessed prospectively per CTCAE v. 4.0 at baseline, weekly during PT, 2 weeks, and 4 weeks following PT and then every 6 months. Results: Median follow-up (FU) was 8 months (2-39 months). All patients had locoregional control at last FU. One woman developed distant metastases 17 months following PT. Acute skin toxicity occurred in all patients; grade 1 (N Z 4), grade 2 (N Z 12) and grade 3 (N Z 1). Grade 1 esophagitis occurred in 11 patients; grade 2 in 4 patients. Grade 2 chest wall pain occurred in 6 patients; grade 3 in 1 patient. The patient with grade 3 skin toxicity and chest wall pain had diffuse painful moist desquamation which worsened and peaked 2 weeks postPT. She had a long standing history of allergies to multiple skin creams. The skin reaction and pain resolved when she stopped using her skin care regimen. One woman experienced rib fracture 18 months post-PT, receiving a cumulative dose of 111 CGE between the 2 courses of RT. Pneumonitis requiring steroid treatment occurred in 1 woman 7 months post-PT. 2 women reported clinical lymphedema at last follow-up. 1 woman reported a non-healing wound at last follow-up. This patient started PT prior to complete wound healing after surgery due to the development of dermal lymphatic gross recurrence within 2 weeks following surgery. Conclusion: Reirradiation with PT in breast cancer patients appears to have acceptable acute toxicity. Longer FU is needed. Author Disclosure: L.A. McGee: None. N. Badar: None. Z. Iftekaruddin: None. J.H. Chang: Partnership; Radiation Oncology Consultants, Chicago Proton Therapy Investments, Elk Grove Radiosurgery, Illinois CyberKnife. V. Gondi: Partnership; Radiation Oncology Consultants. S. Schmidt: None. D. Kaplan: None. S. Gans: None. M. Pankuch: None. W.F. Hartsell: Partnership; Chicago Proton Therapy Investments, Radiation Oncology Consultants, Elk Grove Radiosurgery Incorporation, Illinois CyberKnife.
Results: Forty patients with BC who had surgery for cosmetic breast implant were analyzed. The mean time from that cosmetic surgery to oncologic surgery was 11 years (2-42 years). Before RT 28 patients had one aesthetic surgery, but 11 patients had 2 previous surgeries and 1 patient up to 3. The implant material was: silicone 60% and 40% saline. The location was 30 retro glandular implants, and 7 retro pectoral, and 3 unknown. The mean follow-up was 35 months (24-102), the mean age of BC diagnosis was 54 years (35-76), Left side 23, 3DCRT 37, Stages 0: 12.5% I: 67.5% II: 20%.8 smokers and alcoholic 2, no diabetic patients. Acute radiation toxicity RTOG scale was I Z 29, II Z 10, III Z 1. The local recurrence rate was 5%. A replacement of implant after RT was required in 5 patients. Prosthetic contracture before RT was analyzed with Baker classification I Z 23; II Z 11; III Z 6. Baker III and IV were tested to identify their influence on aesthetics. Age, time since cosmetic surgery, smoking, drinking, prosthetic material, location, RT technique, hormonetherapy, and acute toxicity were not significant; however, in patients who had more than one previous cosmetic surgery a difference was obtained P Z 0.034 assigning RR 4.67 of worst result according to the number of previous surgeries. The results of Harvard reported by patients and the physicians were: Excellent 19 and 21; Good 12, 9; tolerable 3, 7; Poor 6, 3; respectively. 12 patients reported changing results after RT according to Harvard scale; for the physicians just 9, of them, initially had poor or tolerable results in 8 and 6 respectively. The difference between the observers was not significant P Z 0.3 Conclusion: We found a group of patients 27.5% who had a tendency to capsular contracture previous to RT related to the number of surgeries before treatment. The lower result in Harvard scale after RT reported by patient and physicians was 30% and 22.5% respectively, but this change was 20% and 15% for tolerable and poor results. There was an agreement related to cosmetic outcomes according the physicians and patient. It is important to point out; that only 12.5% of the patients needed an implant replacement for disagreement related to esthetic, most of them are satisfied. Author Disclosure: D. Bejarano: None. M. Picasso: None. K. Rojas ´ . Tavella: None. R. Alva: None. O. Furia: None. J. Criales: None. M.A Chiozza: None. M. Girola: None. M. Andrade Irusta: None. H. Donato: None. M. Filomia: None. L.E. Rafailovici: None.
2121 Cosmesis After Breast Irradiation in Patients With Breast Implants ´ . Tavella, R. Alva, D. Bejarano, M. Picasso, K. Rojas Criales, M.A O. Furia, J. Chiozza, M.J. Girola, M. Andrade Irusta, H. Donato, M. Filomia, and L.E. Rafailovici; Vidt Centro Medico - 21st Century Oncology, Buenos Aires, Argentina Purpose/Objective(s): To evaluate the cosmetic results in patients with breast implants treated with radiation therapy (RT) for BC, and analyze factors associated with low cosmetic results considering the assessment of the physicians and patient. Materials/Methods: We selected patients with breast implants and diagnosed BC who received RT. Capsular contracture was evaluated by Baker scale before and after RT and at 3, 6, 12, and 24 months. To objectify the cosmesis, patient and two radiation oncologists were asked to classify results by Harvard scale. To investigate factors that may influence the capsular contracture and cosmetics, T test, chi-square, and Wilcoxon signed-rank were analyzed.
2122 Effect of Regional Nodal Irradiation on Overall Survival in Patients With High-risk Invasive Breast Cancer: A National Cancer Data Base Analysis A.C. Moreno,1 H. Lin,1 I. Bedrosian,1 B.D. Smith,2 G. Babiera,1 M.C. Stauder,1 T.A. Buchholz,3 W.A. Woodward,1 Y. Shen,1 and S.F. Shaitelman1; 1MD Anderson Cancer Center, Houston, TX, 2MD Anderson, Houston, TX, 3The University of Texas MD Anderson Cancer Center, Houston, TX Purpose/Objective(s): The role of regional nodal irradiation (RNI) in specific subgroups of breast cancer patients remains controversial. Using the National Cancer Data Base (NCDB), we aimed to utilize population level data to validate published clinical trial data examining the effect of adding RNI to whole breast irradiation (WBI) on overall survival (OS) of patients with node-positive (pN1-3) or high-risk node-negative (pN0) breast cancer treated with breast conserving surgery (BCS) and adjuvant systemic therapy. Materials/Methods: Women with pN1-3 or high-risk pN0 breast cancer treated with BCS followed by adjuvant systemic therapy and radiation therapy to the whole breast with or without RNI in the United States from 2004 to 2012 were analyzed. High-risk features for pN0 disease included tumor size 5 cm, or tumors measuring 2-4.9 cm that were high grade or hormone receptor negative. Patients with pN1-3 had to undergo a complete axillary lymph node dissection (ALND). A propensity score matched analysis was performed, the Kaplan-Meier method was used to estimate the 5-year OS for the non-matched and matched cohorts, and comparisons were made using log-rank or stratified log-rank tests (for the matched
Volume 96 Number 2S Supplement 2016 cohort) and Cox proportional hazard (PH) regression model or double robust estimation under Cox PH model (for the matched cohort). Subset analyses were performed using matched cohort patients with either pN1-3 or high-risk pN0 disease. Results: A total of 23,567 patients met the criteria; 6,920 (29%) received RNI and 16,647 (71%) received WBI. The use of RNI increased from 25.2% in 2004 to 32.2% in 2012 in the non-matched cohort. In the non-matched cohort, the 5-year OS was 90.8% with RNI and 92.6% with WBI only (P<.0001), whereas in the matched cohort (n Z 10,922), 5-year OS was 92% with RNI and 91.9% with WBI (P Z 0.45). For the matched cohort, the difference in OS remained insignificant in the multivariate model after adjusting for the matching factors (HR 1.02, 95% CI 0.89-1.17). On subset analysis, RNI was not associated with significant improvement of OS in patients with pN1-3 (HR 0.98, 95% CI 0.85-1.13) or high-risk pN0 (HR 1.61, 95% CI 0.972.67) disease. Conclusion: The utilization of RNI in the treatment of high-risk invasive breast cancer has been slowly increasing over time. The largest retrospective study to date, our findings suggest that in women with nodepositive or high-risk node-negative breast cancer who undergo BCS followed by adjuvant systemic therapy, the addition of RNI to whole breast irradiation is not significantly associated with improved overall survival, confirming the findings of the NCIC MA-20 randomized clinical trial. Author Disclosure: A.C. Moreno: None. H. Lin: None. I. Bedrosian: None. B.D. Smith: None. G. Babiera: None. M.C. Stauder: None. T.A. Buchholz: None. W.A. Woodward: None. Y. Shen: None. S.F. Shaitelman: None.
2123 Do Women Who Died of Cardiac Disease Within 10 Years of Breast or Chest Wall Radiation Therapy Violate the “QUANTEC” Cardiac Dose-Volume Histogram Guidelines? L.E. Beaton,1,2 A. Bergman,1,2 A. Nichol,1,2 L. Weir,1,2 and S. Tyldesley1,2; 1BC Cancer Agency, Vancouver, BC, Canada, 2 University of British Columbia, Vancouver, BC, Canada Purpose/Objective(s): Breast and chest wall irradiation (RT) increase the risk of cardiac death. This increased risk is presumed to be a result of the incidental exposure of the heart to radiation. Previous studies have focused on mean heart dose as a measure of radiation exposure. In the modern era of CT based radiation therapy planning, international guidelines (“QUANTEC”) state that for partial heart irradiation a “V25 Gy < 10% (2 Gy/fraction) will be associated with a less than 1% probability of cardiac mortality” in long term follow-up after radiation therapy. We therefore set out to establish whether or not women who died of cardiac disease within 10 years of breast or chest wall radiotherapy had radiation therapy plans that violated these guidelines. We also assessed the maximum dose of radiation delivered to the left anterior descending (LAD) coronary artery and cardiac volume parameters in these patients, on the assumption that the LAD is the critical structure for RT induced cardiac events. Materials/Methods: A provincial database was used to identify all women under 80 years of age diagnosed with early stage breast cancer who were treated with adjuvant RT to the breast or chest wall between 2002 and 2006, who died of cardiac disease. The heart and LAD were retrospectively delineated using a peer-reviewed cardiac atlas. A 1cm radial margin was placed around the LAD to create a planning organ at risk volume (PRV). For each dose plan, DVH’s for the heart and LAD were calculated and the V25 compared to the current QUANTEC guidelines. Results: Between RT start date and June 2015, 76 patients died of a cardiovascular event after breast or chest wall RT. 42 of these patients received left-sided irradiation, and 34 right-sided irradiation. For the left sided cases, median time from diagnosis to death was 6.7 years. Later cardiac deaths (more than 9 years after diagnosis) were more common for left-sided cases when compared to right-sided cases (38% vs 24%).Radiation therapy plans were available for 31 of the left-sided
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cases. 11 cases were treated without CT planning. 19 patients received radiation doses of 40-42.56 Gy over 16 fractions, and 12 patients doses of 45-50.4 Gy over 25-28 fractions. The heart V25 did not exceed 10% in any of our 31 left sided cases. Equivalent doses in 2-Gy fractions (EQD2) were calculated from the DVH using a/ b 2 Gy. The average maximum heart dose was 35.6 Gy (SD 16.1). The average maximum dose to the LAD was 26.2 Gy (SD 19.7) and 40.9 Gy (SD 15.6) to the LAD PRV. Conclusion: This study has shown that the QUANTEC guidelines were not violated in our cohort of patients that died of cardiac disease after leftsided breast RT. As only 38% of patients died later than 9 years after radiation therapy it may be that pre-existing cardiac risk factors were a dominant factor for cardiac death as opposed to the effect of RT. It remains unclear as to the exact mechanism of increased cardiac mortality as a result of RT, but radiation to the LAD may be more important than the heart V25 in predicting cardiac mortality. Author Disclosure: L.E. Beaton: None. A. Bergman: None. A. Nichol: Research Grant; Varian Medical Systems. Speaker’s Bureau; Varian Medical Systems. L. Weir: None. S. Tyldesley: None.
2124 Assessment of National Practice Patterns of Radiation Therapy Use after Neoadjuvant Chemotherapy for Breast Cancer C.T. Murphy,1 E. Handorf,1 E.R. Sigurdson,1 S.B. Hayes,1 P. Anderson,2 S. Weiss,1 T. Shaikh,1 J.M. Daly,1 M. Boraas,1 and R.J. Bleicher1; 1Fox Chase Cancer Center, Philadelphia, PA, 2Fox Chase Cancer Center, Philadelphia, PA Purpose/Objective(s): To assess patterns and predictors of radiation therapy (RT) use in women receiving neoadjuvant chemotherapy (NAC) in a national breast cancer registry. Materials/Methods: Using the National Cancer Database, we included women with clinical stage III and clinical node-positive stage II breast cancer, known receptor and HER2 status receiving NAC followed by surgery with a known pathologic stage. Significant differences in RT use were analyzed according to surgery type by using the chi-square test. Significant predictors of RT use were identified on multivariate analysis (MVA) via generalized estimating equations adjusting for age, race, insurance type, facility type, comorbidity score, clinical T- and N-stage, pathologic response, tumor grade, ER/PR status, HER2 status, and surgery type, defined as breast conservation (BCS), mastectomy (Mx), and Mx with reconstruction (MxR). Results: A total of 17567 women were included, with 5344 (30%) treated with BCS and 12223 (70%) treated with Mx, of which 3404 underwent MxR (28% of all Mx patients). A total of 10029 (57%) were clinical T12; 11313 (64%) were clinical N1-3; 7347 (42%) had clinical stage III disease; 10592 (60%) were ER/PR+; 4765 (27%) were HER2+. In the BCS cohort, 56% received breast RT, 34% received breast and regional nodal irradiation (RNI) and 10% did not receive RT. On univariate analysis, RT use did not vary according to clinical T- or N-stage, ER/PR status, or HER2 status. Although RT use did not vary according to pathologic nodal response, RT use was more common with primary tumor pathologic downstaging when compared to stable and progressive disease (91% vs 89% vs 84%, P Z 0.02), but not with upstaging. In the Mx cohort, 20% received chest wall RT, 45% received chest wall + RNI, RT was omitted in 4284 (35%). Mx alone was significantly more common in women with clinical T2 primary tumors (46%), clinical N0 disease (52%), ER/PR(-) disease (41%), and Her-2+ status (36%). RT use did not vary according to primary tumor response, but was more commonly omitted in women with stable (42%) or responsive (31%) nodal disease compared to nodal upstaging (25%), P<0.001. Omission of RT was more common in women undergoing MxR vs Mx alone (42% vs 32%, P<0.001). On MVA, advanced clinical nodal stage was the strongest predictor of RT use after NAC. MxR was more strongly associated with RT omission (OR 0.70, 95% CI 0.63-0.77), than with receptor status, HER2 status, or nodal response. Primary tumor response did not predict for RT use.