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Local Recurrence and Overall Survival Rate After Hypofractionated Irradiation With Concomitant Boost in Early Breast Cancer
International Journal of RadiatiOncology Biology Physics
S224 size, margin width, and necrosis. Eighty-five percent of pts were ER+ compared to 97% in E5194. The median pre-assay physician estimate of 10yr risk of IBE was 20.8 % (range, 6-40) for any IBE and 10.9% (range, 3-25) for invasive IBE. Physicians correspondingly recommended XRT in 72.7%, HT in 93.6%, and additional surgery in 18.2% of the cases. PostDCIS score estimates of IBE risk and analysis of change in tx recommendations from pre- to post-assay will be presented at the meeting. Conclusions: Establishing the impact of the DCIS Score on tx recommendations is critical to understanding the utility of this genomic assay in clinical practice. Of note, the CP factors differ from the validation study (E5194) in proportions of younger pts (< 50 yr), ER+ margins < 3 mm. The pre-assay IBE risk estimates and the corresponding pre-assay tx recommendations are consistent with current practices, including the recommendation of XRT w 73% of the time. The full analysis will report the impact of incorporating the DCIS Score result into clinical practice.
Scientific Abstract 2016; Table Characteristic Age (years) DCIS Size (mm) Nuclear Grade
Closest Margin (mm) Necrosis
Median (Range) < 50 Median (Range) Low Intermediate High Median (Range) <3 Present
Current Study n Z 110 61 (36-83) 15.5% 8 (1-115) 20% 46.4% 33.6% 3 (0-20) 48.1% 63.6%
E5194 n Z 327 20.2% 7 8.9% 57.2% 33.9% 3.0% 34.9%
Author Disclosure: C.E. Leonard: F. Honoraria; Genomic Health, Inc. L. Funding Other; Genomic Health, Inc. R.Y. Lei: None. M.D. Alvarado: None. J. Guenther: F. Honoraria; Genomic Health, Inc. J.E. Hagans: F. Honoraria; Genomic Health, Inc. H. Speakers Bureau; Genomic Health, Inc. J.B. Manders: F. Honoraria; Genomic Health, Inc. I. Travel Expenses; Genomic Health, Inc. L. Funding Other; Genomic Health, Inc. M.J. Schultz: G. Consultant; Genomic Health, Inc. K. Advisory Board; Genomic Health, Inc. L. Funding Other; Genomic Health, Inc. A.P. Sing: A. Employee; Genomic Health, Inc. M. Stock; Genomic Health, Inc. N. Stock Options; Genomic Health, Inc. M.S. Broder: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. E. Chang: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. D. Cherepanov: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. M. Eagan: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. W.C. Hsiao: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. D.L. Carter: None.
2017 Development of the Breast Immobilization System in Prone Setup: The Effect of Bra in Prone Position to Eliminate the Breast Setup Error M. Kawamura,1,2 Y. Maeda,1 S. Takamatsu,1 H. Tamamura,1 K. Yamamoto,1 Y. Tameshige,1 M. Sasaki,1 Y. Satoh,1 and S. Asahi3; 1 Fukui Prefectural Hospital, Fukui, Japan, 2Nagoya University, Nagoya, Japan, 3Fukui University, Fukui, Japan Purpose/Objective(s): An accurate and reproducible positioning of the breast is difficult due to its deformability and softness thus targeting breast tumor with fractionated radiation therapy using external radiation beam is difficult. The aim of this study is to develop a breast immobilization system in prone position with the use of newly designed bra. Materials/Methods: For the assessment of the accuracy of prone position fixation of breast tumor, 21 breast cancer patients with 25 lesions were recruited. The bra used in this verification was costumed from commercially available bra. For the remake of the bra, the covering cloth of bra cup was removed and all metal
parts were replaced by plastic materials. MRI images were acquired in prone position with and without bra alternately for two times each and for each series, patients were asked to step off from MRI table and re-set up in prone position. Each pairs of images with and without the bra were superimposed respectively to match the shape of skin-surface using commercially available image guide workstation, and the maximum tumor dislocation in three axes (anterior-posterior [AP]; superior-inferior [SI]; medial-lateral [ML]) were measured. Required set up margin was calculated as: Required margin Z mean dislocation (mm) + 2.5STD. Volumetric overlap of the tumor was also evaluated using radiation therapy support software. To eliminate the volumetric uncertainties comes from delineation of the target, target was contoured once on diagnostic MRI and it was copied to the images with and without bra using radiation therapy support software by radiation oncologist thus each paired images have same tumor volume. Then the therapist fused two MRI, with or without bra, by skin surface, and the overlap of the tumor volume were compared. Results: Median breast size was 498 cc (156-1432 cc), tumor size was 5.8 cc (0.5-47.2 cc). Maximum tumor dislocation with/without bra were ML1.20.6/ 2.10.9, AP 1.10.8/2.61.6, SI 1.10.8/2.91.6 mm and required set up margin were ML3.1/6.9, AP 2.7/6.6, SI 3.1/4.4 mm. The overlap ratio of the tumor volume was 79.2% with bra and 66.3% without bra in average if margin was not added. By adding calculated margin above, the volume overlap ratio improved to more than 99% in both cases, with and without bra. Conclusions: The use of immobilizing bra reduce setup margin for prone position fixation of breast tumor. Author Disclosure: M. Kawamura: None. Y. Maeda: None. S. Takamatsu: None. H. Tamamura: None. K. Yamamoto: None. Y. Tameshige: None. M. Sasaki: None. Y. Satoh: None. S. Asahi: None.
2018 Local Recurrence and Overall Survival Rate After Hypofractionated Irradiation With Concomitant Boost in Early Breast Cancer K. Saksornchai and P. Rojpornpradit; Division of Therapeutic Radiology and Oncology, Department of Radiology, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand Purpose/Objective(s): The purpose of this study was to evaluate the local recurrence and survival rate of hypofractionated whole breast irradiation plus concomitant boost (HFC) comparing with conventional irradiation and sequential boost (CFS). Materials/Methods: This is a prospective non-randomized study. Between October 2009 and June 2010, seventy-three women with early breast cancer who had undergone breast-conserving surgery were enrolled in this study. Eligibility included patient aged 18 years, pT1-3N0-1M0, and ductal carcinoma. For the whole breast irradiation, 67.5% and 32.5% of patients were planned by 2D and 3D techniques, respectively. 36 patients (49.3%) received conventional irradiation of 50 Gy in 25 fractions to the whole breast with sequential electron boost of 10-16 Gy in 5-8 fractions. 37 patients (50.6%) received hypofractionated irradiation of 43.2 Gy in 16 fractions to the whole breast and a daily tumor bed boost of 0.6 Gy. Radiation boost treatment was planned using 2D and 3D techniques. 2D planning (89%) utilized preoperative imaging and surgical scar to define the location of the tumor bed, whereas CT planning (11%) was used for 3D technique. The total dose to the tumor bed in the CFS and HFC arms was 60-66 Gy and 52.8 Gy, respectively. Results: At a median follow-up of 49 months (range 21-62 months), one patient in the HFC and one in the CFS experienced local recurrences. Both of them were planned for tumor bed boost by 2D technique and their lesions were isolated local recurrence which occurred in the other quadrant of the index breast. However, there was no significant difference between the CFS and HFC arms in terms of local recurrence (2.7% vs 2.8%, respectively) p Z 1.000 and overall survival rates (97.2% vs 97.3% , p Z 1.000). Mean time to recurrence was 60.6 and 58.7 months for conventional and hypofractionated groups, respectively (p Z 0.327). The two planning techniques were not associated with an increase in local recurrence rate (p Z 1.000) on univariate analysis. Conclusions: HFC offered no significant difference in terms of local control and overall survival rates. 3D planning is preferred for tumor bed boost planning. Long-term follow-up is needed.
Volume 90 Number 1S Supplement 2014 Author Disclosure: K. Saksornchai: None. P. Rojpornpradit: None.
2019 Comparison of 2 Radiation Schedules in the Adjuvant Treatment of Early-Stage Breast Carcinoma With Long-Term Follow-Up O. Vujovic,1 E. Yu,2 A. Cherian,3 A. Dar,2 L. Stitt,2 and F. Perera2; 1 London Regional Cancer Program, London, Ontario, ON, Canada, 2 London Regional Cancer Program, London, ON, Canada, 3Royal Air Force, Moray, United Kingdom Purpose/Objective(s): A retrospective chart review was conducted to determine if there was any difference in local recurrence rates between two common radiation schedules for adjuvant whole breast radiation in early stage breast carcinoma. Materials/Methods: There were 499 patients with T1-T2, NO breast carcinoma treated with breast conserving surgery and whole breast radiation and without adjuvant systemic treatment at a single institution from January 1985 to December 1992. There were two commonly used fractionation schedules at this time. The first was 5000 cGy in 25 fractions over 5 weeks and the second was 4000 cGy in 15 or 16 fractions plus a boost of 500-1250 cGy in 3-5 fractions. Kaplan-Meir estimates of time to local-recurrence were calculated for the two groups. Results: The median follow-up was 17.4 years. The median age was 60. There were 191 (38.3%) patients treated with 5000 cGy in 25 fractions and 308 (61.7%) patients treated with 4000 cGy in 15/16 fractions plus a boost. The most commonly used boost fractionation was 1250 cGy in 5 fractions in 170 patients (55%). There was no statistically significant difference in local recurrence rate between the two fractionation schedules. The 5, 10 and 15 year local failure rate was 4.9%, 10.7% and 12.5% for the 15/16 fractions plus boost group and 2.7%, 13.1% and 19.2% for the 25 fraction group. Conclusions: Standard whole breast radiation with 5000/25 without a boost results in similar local controls rates as a hypofractionated schedule which includes a boost. Therefore, the practice of boosting all breast patients may not be necessary when using a standard fractionation schedule. Author Disclosure: O. Vujovic: None. E. Yu: None. A. Cherian: None. A. Dar: None. L. Stitt: None. F. Perera: None.
2020 Dose to Organs at Risk (OAR) When Covering the Internal Mammary Nodes in Breast Cancer Patients: A Quantitative Comparison of VMAT, Partially-Wide Tangents (PWT), and Photon-Electron (P-E) M. Knoll, V. Dumane, E. Steinberger, S. Green, and R.L. Bakst; Mount Sinai Medical Center, New York, NY Purpose/Objective(s): In the NCIC-CTG MA.20 trial, patients (pts) who received regional nodal irradiation after breast conserving surgery had improved disease free survival. Accordingly, coverage of the internal mammary nodes may become more frequent, and targeting them can present treatment planning challenges. We have previously reported that VMAT offers dosimetric sparing of the ipsilateral lung, total lung, heart and left ventricle, when compared with 3D planning. However, whenever transitioning from conventional to conformal techniques, the dose to surrounding OAR needs careful evaluation. Our aim was to compare the dose to OAR when using both non-conformal and conformal radiation techniques. Materials/Methods: We compared plans for 40 pts (20 right-sided and 20 left-sided). The prescribed dose was 50 Gy in 2 fractions. The VMAT plans consisted of 4 complementary arcs within a 215 degree range using 6 MV photons. PWT plans utilized 6 MV photons while P-E plans used 6 MV photons and electrons of energy no more than 12 MV. Coverage criteria used were PTV (inclusive of all the nodes) D95 50 Gy, V95 98%, PTV D05 115% for VMAT and PWT while D05 125% for P-E plans. The doses to the spinal cord, brachial plexus, stomach (left-sided cases), bowel, liver (right-sided cases), and esophagus were recorded. Significance testing was performed using Wilcoxon Sign rank test for non-parametric hypothesis testing. IRB approval was obtained.
Poster Viewing Abstracts S225 Results: The use of VMAT significantly increased the maximum dose to the esophagus, spinal cord, stomach and bowel by 23 Gy, 22 Gy, 12 Gy, and 6 Gy respectively (all p < 0.05) (Table). Utilizing VMAT increased the mean stomach dose and esophagus dose by 5 Gy and 7 Gy, respectively. PE plans led to the highest brachial plexus max dose. Conclusions: VMAT led to significantly higher spinal cord, esophagus, bowel, and stomach doses as compared to conventional 3D-planning. The clinical significance of these dosimetric differences remains to be determined. We advocate for contouring of all normal structures within the treatment field when using conformal techniques for IMN coverage and potentially utilizing these organs in the treatment planning optimization algorithm.
Scientific Abstract 2020; Table and VMAT vs P-E
Comparison of OAR Doses: VMAT vs PWT
PWT Bowel Max (Gy) Stomach Max (Gy) Stomach Mean (Gy) Brachial Plexus Max (Gy) Esophagus Max (Gy) Esophagus Mean (Gy) Spinal Cord Max (Gy) Liver Mean (Gy)
P-E
VMAT
12.87* (SE 3.08)
17.10 (SE 2.83)
19.52* (SE 4.58)
26.52* (SE 5.35)
31.55 (SE 3.83)
2.38* (SE 0.71)
4.80 (SE 1.01)
7.10 (SE 1.14)
56.6 (SE 0.93)
60.38* (SE 1.53)
56.66 (SE 0.62)
28.11* (SE 3.10)
25.55* (SE 3.27)
48.1 (SE 0.93)
3.30* (SE 0.45)
3.96* (SE 0.39)
10.12 (SE 0.4)
8.32* (SE 1.23)
8.17* (SE 1.18)
30.57 (SE 1.14)
3.60* (SE 0.60)
9.06 (SE 1.11)
6.73 (SE 0.63)
11.26* SE (2.92)
Key: SE Z standard error * Z indicates significance, P Z <.05 Author Disclosure: M. Knoll: None. V. Dumane: None. E. Steinberger: None. S. Green: None. R.L. Bakst: None.
2021 Comparison of the Volume and Localization of Lumpectomy Cavity Delineated by Clips and Seroma Based on 4DCT Scan for ExternalBeam Partial Breast Irradiation After Breast Conserving Surgery Y. Ding,1 J. Li,2 W. Wang,2 M. Zhifang,1 M. Xu,2 and Q. Shao2; 1 Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, China, 2Shandong Cancer Hospital, Jinan, China Purpose/Objective(s): To explore the volume and localization of the lumpectomy cavity delineated separately by metal clips, seroma, both the clips and seroma based on the four-dimensional computed tomography (4DCT) in the free-breathing (FB) state. Materials/Methods: Fifteen breast cancer patients after breast-conserving surgery were recruited for EB-PBI. The gross tumor volume (GTV) formed by the clips, the seroma, both the clips and seroma were defined as GTVc, GTVs and GTVc+s, respectively. GTVc, GTVs and GTVc+s were delineated by one radiation oncologist on the CT images from 10 phases of the breath cycle. The GTV volume and the distance between the center of GTVc, GTVs and GTVc+s were all recorded. Conformity index (CI), degree of inclusion (DI) were calculated for GTVc vs GTVs, GTVc vs GTVc+s, and GTVs vs GTVc+s, respectively. Results: The volume of GTVc, GTVs, and GTVc+s were (23.1513.34) cm3, (19.2717.52) cm3 and (24.6016.72) cm3, respectively. There was significant difference among the volume of GTVc, GTVs and GTVc+s (F Z 10.237, P Z 0.000). The DI of GTVs included in GTVc was significantly larger than GTVc included in GTVs (0.670.21 vs 0.480.20; t Z -8.287, P Z 0.000). The DI of GTVc included in GTVc+s was significantly larger than GTVc+s included in GTVc (0.820.11 vs 0.710.19; t Z -5.794, P Z 0.000). The DI of GTVs included in GTVc+s was significantly superior to GTVc+s included in GTVs (0.910.14 vs 0.520.22; t Z -15.485, P Z 0.000). The CI of GTVc vs GTVs, GTVc vs GTVc+s, and GTVs vs GTVc+s were 0.360.14, 0.600.14,
S224 size, margin width, and necrosis. Eighty-five percent of pts were ER+ compared to 97% in E5194. The median pre-assay physician estimate of 10yr risk of IBE was 20.8 % (range, 6-40) for any IBE and 10.9% (range, 3-25) for invasive IBE. Physicians correspondingly recommended XRT in 72.7%, HT in 93.6%, and additional surgery in 18.2% of the cases. PostDCIS score estimates of IBE risk and analysis of change in tx recommendations from pre- to post-assay will be presented at the meeting. Conclusions: Establishing the impact of the DCIS Score on tx recommendations is critical to understanding the utility of this genomic assay in clinical practice. Of note, the CP factors differ from the validation study (E5194) in proportions of younger pts (< 50 yr), ER+ margins < 3 mm. The pre-assay IBE risk estimates and the corresponding pre-assay tx recommendations are consistent with current practices, including the recommendation of XRT w 73% of the time. The full analysis will report the impact of incorporating the DCIS Score result into clinical practice.
Scientific Abstract 2016; Table Characteristic Age (years) DCIS Size (mm) Nuclear Grade
Closest Margin (mm) Necrosis
Median (Range) < 50 Median (Range) Low Intermediate High Median (Range) <3 Present
Current Study n Z 110 61 (36-83) 15.5% 8 (1-115) 20% 46.4% 33.6% 3 (0-20) 48.1% 63.6%
E5194 n Z 327 20.2% 7 8.9% 57.2% 33.9% 3.0% 34.9%
Author Disclosure: C.E. Leonard: F. Honoraria; Genomic Health, Inc. L. Funding Other; Genomic Health, Inc. R.Y. Lei: None. M.D. Alvarado: None. J. Guenther: F. Honoraria; Genomic Health, Inc. J.E. Hagans: F. Honoraria; Genomic Health, Inc. H. Speakers Bureau; Genomic Health, Inc. J.B. Manders: F. Honoraria; Genomic Health, Inc. I. Travel Expenses; Genomic Health, Inc. L. Funding Other; Genomic Health, Inc. M.J. Schultz: G. Consultant; Genomic Health, Inc. K. Advisory Board; Genomic Health, Inc. L. Funding Other; Genomic Health, Inc. A.P. Sing: A. Employee; Genomic Health, Inc. M. Stock; Genomic Health, Inc. N. Stock Options; Genomic Health, Inc. M.S. Broder: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. E. Chang: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. D. Cherepanov: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. M. Eagan: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. W.C. Hsiao: A. Employee; Partnership for Health Analytic Research, LLC, which was paid by Genomic Health, Inc. to conduct this research. D.L. Carter: None.
2017 Development of the Breast Immobilization System in Prone Setup: The Effect of Bra in Prone Position to Eliminate the Breast Setup Error M. Kawamura,1,2 Y. Maeda,1 S. Takamatsu,1 H. Tamamura,1 K. Yamamoto,1 Y. Tameshige,1 M. Sasaki,1 Y. Satoh,1 and S. Asahi3; 1 Fukui Prefectural Hospital, Fukui, Japan, 2Nagoya University, Nagoya, Japan, 3Fukui University, Fukui, Japan Purpose/Objective(s): An accurate and reproducible positioning of the breast is difficult due to its deformability and softness thus targeting breast tumor with fractionated radiation therapy using external radiation beam is difficult. The aim of this study is to develop a breast immobilization system in prone position with the use of newly designed bra. Materials/Methods: For the assessment of the accuracy of prone position fixation of breast tumor, 21 breast cancer patients with 25 lesions were recruited. The bra used in this verification was costumed from commercially available bra. For the remake of the bra, the covering cloth of bra cup was removed and all metal
parts were replaced by plastic materials. MRI images were acquired in prone position with and without bra alternately for two times each and for each series, patients were asked to step off from MRI table and re-set up in prone position. Each pairs of images with and without the bra were superimposed respectively to match the shape of skin-surface using commercially available image guide workstation, and the maximum tumor dislocation in three axes (anterior-posterior [AP]; superior-inferior [SI]; medial-lateral [ML]) were measured. Required set up margin was calculated as: Required margin Z mean dislocation (mm) + 2.5STD. Volumetric overlap of the tumor was also evaluated using radiation therapy support software. To eliminate the volumetric uncertainties comes from delineation of the target, target was contoured once on diagnostic MRI and it was copied to the images with and without bra using radiation therapy support software by radiation oncologist thus each paired images have same tumor volume. Then the therapist fused two MRI, with or without bra, by skin surface, and the overlap of the tumor volume were compared. Results: Median breast size was 498 cc (156-1432 cc), tumor size was 5.8 cc (0.5-47.2 cc). Maximum tumor dislocation with/without bra were ML1.20.6/ 2.10.9, AP 1.10.8/2.61.6, SI 1.10.8/2.91.6 mm and required set up margin were ML3.1/6.9, AP 2.7/6.6, SI 3.1/4.4 mm. The overlap ratio of the tumor volume was 79.2% with bra and 66.3% without bra in average if margin was not added. By adding calculated margin above, the volume overlap ratio improved to more than 99% in both cases, with and without bra. Conclusions: The use of immobilizing bra reduce setup margin for prone position fixation of breast tumor. Author Disclosure: M. Kawamura: None. Y. Maeda: None. S. Takamatsu: None. H. Tamamura: None. K. Yamamoto: None. Y. Tameshige: None. M. Sasaki: None. Y. Satoh: None. S. Asahi: None.
2018 Local Recurrence and Overall Survival Rate After Hypofractionated Irradiation With Concomitant Boost in Early Breast Cancer K. Saksornchai and P. Rojpornpradit; Division of Therapeutic Radiology and Oncology, Department of Radiology, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand Purpose/Objective(s): The purpose of this study was to evaluate the local recurrence and survival rate of hypofractionated whole breast irradiation plus concomitant boost (HFC) comparing with conventional irradiation and sequential boost (CFS). Materials/Methods: This is a prospective non-randomized study. Between October 2009 and June 2010, seventy-three women with early breast cancer who had undergone breast-conserving surgery were enrolled in this study. Eligibility included patient aged 18 years, pT1-3N0-1M0, and ductal carcinoma. For the whole breast irradiation, 67.5% and 32.5% of patients were planned by 2D and 3D techniques, respectively. 36 patients (49.3%) received conventional irradiation of 50 Gy in 25 fractions to the whole breast with sequential electron boost of 10-16 Gy in 5-8 fractions. 37 patients (50.6%) received hypofractionated irradiation of 43.2 Gy in 16 fractions to the whole breast and a daily tumor bed boost of 0.6 Gy. Radiation boost treatment was planned using 2D and 3D techniques. 2D planning (89%) utilized preoperative imaging and surgical scar to define the location of the tumor bed, whereas CT planning (11%) was used for 3D technique. The total dose to the tumor bed in the CFS and HFC arms was 60-66 Gy and 52.8 Gy, respectively. Results: At a median follow-up of 49 months (range 21-62 months), one patient in the HFC and one in the CFS experienced local recurrences. Both of them were planned for tumor bed boost by 2D technique and their lesions were isolated local recurrence which occurred in the other quadrant of the index breast. However, there was no significant difference between the CFS and HFC arms in terms of local recurrence (2.7% vs 2.8%, respectively) p Z 1.000 and overall survival rates (97.2% vs 97.3% , p Z 1.000). Mean time to recurrence was 60.6 and 58.7 months for conventional and hypofractionated groups, respectively (p Z 0.327). The two planning techniques were not associated with an increase in local recurrence rate (p Z 1.000) on univariate analysis. Conclusions: HFC offered no significant difference in terms of local control and overall survival rates. 3D planning is preferred for tumor bed boost planning. Long-term follow-up is needed.
Volume 90 Number 1S Supplement 2014 Author Disclosure: K. Saksornchai: None. P. Rojpornpradit: None.
2019 Comparison of 2 Radiation Schedules in the Adjuvant Treatment of Early-Stage Breast Carcinoma With Long-Term Follow-Up O. Vujovic,1 E. Yu,2 A. Cherian,3 A. Dar,2 L. Stitt,2 and F. Perera2; 1 London Regional Cancer Program, London, Ontario, ON, Canada, 2 London Regional Cancer Program, London, ON, Canada, 3Royal Air Force, Moray, United Kingdom Purpose/Objective(s): A retrospective chart review was conducted to determine if there was any difference in local recurrence rates between two common radiation schedules for adjuvant whole breast radiation in early stage breast carcinoma. Materials/Methods: There were 499 patients with T1-T2, NO breast carcinoma treated with breast conserving surgery and whole breast radiation and without adjuvant systemic treatment at a single institution from January 1985 to December 1992. There were two commonly used fractionation schedules at this time. The first was 5000 cGy in 25 fractions over 5 weeks and the second was 4000 cGy in 15 or 16 fractions plus a boost of 500-1250 cGy in 3-5 fractions. Kaplan-Meir estimates of time to local-recurrence were calculated for the two groups. Results: The median follow-up was 17.4 years. The median age was 60. There were 191 (38.3%) patients treated with 5000 cGy in 25 fractions and 308 (61.7%) patients treated with 4000 cGy in 15/16 fractions plus a boost. The most commonly used boost fractionation was 1250 cGy in 5 fractions in 170 patients (55%). There was no statistically significant difference in local recurrence rate between the two fractionation schedules. The 5, 10 and 15 year local failure rate was 4.9%, 10.7% and 12.5% for the 15/16 fractions plus boost group and 2.7%, 13.1% and 19.2% for the 25 fraction group. Conclusions: Standard whole breast radiation with 5000/25 without a boost results in similar local controls rates as a hypofractionated schedule which includes a boost. Therefore, the practice of boosting all breast patients may not be necessary when using a standard fractionation schedule. Author Disclosure: O. Vujovic: None. E. Yu: None. A. Cherian: None. A. Dar: None. L. Stitt: None. F. Perera: None.
2020 Dose to Organs at Risk (OAR) When Covering the Internal Mammary Nodes in Breast Cancer Patients: A Quantitative Comparison of VMAT, Partially-Wide Tangents (PWT), and Photon-Electron (P-E) M. Knoll, V. Dumane, E. Steinberger, S. Green, and R.L. Bakst; Mount Sinai Medical Center, New York, NY Purpose/Objective(s): In the NCIC-CTG MA.20 trial, patients (pts) who received regional nodal irradiation after breast conserving surgery had improved disease free survival. Accordingly, coverage of the internal mammary nodes may become more frequent, and targeting them can present treatment planning challenges. We have previously reported that VMAT offers dosimetric sparing of the ipsilateral lung, total lung, heart and left ventricle, when compared with 3D planning. However, whenever transitioning from conventional to conformal techniques, the dose to surrounding OAR needs careful evaluation. Our aim was to compare the dose to OAR when using both non-conformal and conformal radiation techniques. Materials/Methods: We compared plans for 40 pts (20 right-sided and 20 left-sided). The prescribed dose was 50 Gy in 2 fractions. The VMAT plans consisted of 4 complementary arcs within a 215 degree range using 6 MV photons. PWT plans utilized 6 MV photons while P-E plans used 6 MV photons and electrons of energy no more than 12 MV. Coverage criteria used were PTV (inclusive of all the nodes) D95 50 Gy, V95 98%, PTV D05 115% for VMAT and PWT while D05 125% for P-E plans. The doses to the spinal cord, brachial plexus, stomach (left-sided cases), bowel, liver (right-sided cases), and esophagus were recorded. Significance testing was performed using Wilcoxon Sign rank test for non-parametric hypothesis testing. IRB approval was obtained.
Poster Viewing Abstracts S225 Results: The use of VMAT significantly increased the maximum dose to the esophagus, spinal cord, stomach and bowel by 23 Gy, 22 Gy, 12 Gy, and 6 Gy respectively (all p < 0.05) (Table). Utilizing VMAT increased the mean stomach dose and esophagus dose by 5 Gy and 7 Gy, respectively. PE plans led to the highest brachial plexus max dose. Conclusions: VMAT led to significantly higher spinal cord, esophagus, bowel, and stomach doses as compared to conventional 3D-planning. The clinical significance of these dosimetric differences remains to be determined. We advocate for contouring of all normal structures within the treatment field when using conformal techniques for IMN coverage and potentially utilizing these organs in the treatment planning optimization algorithm.
Scientific Abstract 2020; Table and VMAT vs P-E
Comparison of OAR Doses: VMAT vs PWT
PWT Bowel Max (Gy) Stomach Max (Gy) Stomach Mean (Gy) Brachial Plexus Max (Gy) Esophagus Max (Gy) Esophagus Mean (Gy) Spinal Cord Max (Gy) Liver Mean (Gy)
P-E
VMAT
12.87* (SE 3.08)
17.10 (SE 2.83)
19.52* (SE 4.58)
26.52* (SE 5.35)
31.55 (SE 3.83)
2.38* (SE 0.71)
4.80 (SE 1.01)
7.10 (SE 1.14)
56.6 (SE 0.93)
60.38* (SE 1.53)
56.66 (SE 0.62)
28.11* (SE 3.10)
25.55* (SE 3.27)
48.1 (SE 0.93)
3.30* (SE 0.45)
3.96* (SE 0.39)
10.12 (SE 0.4)
8.32* (SE 1.23)
8.17* (SE 1.18)
30.57 (SE 1.14)
3.60* (SE 0.60)
9.06 (SE 1.11)
6.73 (SE 0.63)
11.26* SE (2.92)
Key: SE Z standard error * Z indicates significance, P Z <.05 Author Disclosure: M. Knoll: None. V. Dumane: None. E. Steinberger: None. S. Green: None. R.L. Bakst: None.
2021 Comparison of the Volume and Localization of Lumpectomy Cavity Delineated by Clips and Seroma Based on 4DCT Scan for ExternalBeam Partial Breast Irradiation After Breast Conserving Surgery Y. Ding,1 J. Li,2 W. Wang,2 M. Zhifang,1 M. Xu,2 and Q. Shao2; 1 Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, China, 2Shandong Cancer Hospital, Jinan, China Purpose/Objective(s): To explore the volume and localization of the lumpectomy cavity delineated separately by metal clips, seroma, both the clips and seroma based on the four-dimensional computed tomography (4DCT) in the free-breathing (FB) state. Materials/Methods: Fifteen breast cancer patients after breast-conserving surgery were recruited for EB-PBI. The gross tumor volume (GTV) formed by the clips, the seroma, both the clips and seroma were defined as GTVc, GTVs and GTVc+s, respectively. GTVc, GTVs and GTVc+s were delineated by one radiation oncologist on the CT images from 10 phases of the breath cycle. The GTV volume and the distance between the center of GTVc, GTVs and GTVc+s were all recorded. Conformity index (CI), degree of inclusion (DI) were calculated for GTVc vs GTVs, GTVc vs GTVc+s, and GTVs vs GTVc+s, respectively. Results: The volume of GTVc, GTVs, and GTVc+s were (23.1513.34) cm3, (19.2717.52) cm3 and (24.6016.72) cm3, respectively. There was significant difference among the volume of GTVc, GTVs and GTVc+s (F Z 10.237, P Z 0.000). The DI of GTVs included in GTVc was significantly larger than GTVc included in GTVs (0.670.21 vs 0.480.20; t Z -8.287, P Z 0.000). The DI of GTVc included in GTVc+s was significantly larger than GTVc+s included in GTVc (0.820.11 vs 0.710.19; t Z -5.794, P Z 0.000). The DI of GTVs included in GTVc+s was significantly superior to GTVc+s included in GTVs (0.910.14 vs 0.520.22; t Z -15.485, P Z 0.000). The CI of GTVc vs GTVs, GTVc vs GTVc+s, and GTVs vs GTVc+s were 0.360.14, 0.600.14,