Breast Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_4_3360 - Post-Mastectomy Radiation Therapy in Stage II N1 Breast Cancer Patients Is Associated with Improved Survival with Different Sub-Type.

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Post-Mastectomy Radiation Therapy in Stage II N1 Breast Cancer Patients Is Associated with Improved Survival with Different Sub-Type.
W. K. Chuang, Y. C. Tsai, B. L. Yu, C. F. Horng, and S. H. Cheng; Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan

Purpose/Objective(s): Post-operative radiotherapy (PMRT) has shown to reduce locoregional recurrence and increase disease-free survival and overall survival in high risk breast cancer patients, in combination with chemotherapy or hormone therapy. For stage II breast cancer, PMRT was still under discussion. Current NCCN guideline recommend N1 patients to receive PMRT. This study aims to evaluate the impact of PMRT on different breast cancer subtype.

Materials/Methods: Between 1990 to 2013, there were 1252 patients with Stage II breast cancer (T1-2 with one to three positive) treated by mastectomy at the Koo Foundation Sun Yat-Sen Cancer Center. We divided breast cancer into luminal (ER/PR+, HER2-), HER2 overexpressed, and triple negative subtype. Overall survival (OS) and disease-free survival (DFS) were calculated by Kaplan-Meier method.

Results: The median follow up time was 80 months. In this cohort, luminal, HER2 overexpressed, triple negative subtypes accounted for 59%, 28.4%,12.6%, respectively. Among them, 765 (61%) of patients were treated with PMRT. Survival analyses revealed that PMRT was significant improved 10 years OS and DFS in all subtypes except HER2 subtype (Table 1). The absolute 10-year survival gain was 8% in luminal subtype, and 25% in triple negative subtype. Further propensity score matching results are pending. Table 1. Luminal, HER2 and triple negative breast cancer with or without PMRT
N Radiotherapy DFS p value OS P value
All 765 Yes 82% <0.001 84% 0.0043
487 No 68% 78%
Luminal 406 Yes 78% 0.0078 87% 0.0089
332 No 72% 79%
HER2 240 Yes 75% 0.0173 78% 0.5696
116 No 67% 76%
Triple negative 119 Yes 80% 0.0019 89% 0.0053
39 No 56% 64%

Conclusion: PMRT improved long term DFS in women with pT1-T2/N1 breast cancer in luminal and triple negative breast cancers.

Author Disclosure: W. Chuang: None. Y. Tsai: None. B. Yu: None. C. Horng: None. S.H. Cheng: None.

Wei-Kai Chuang, MD

Biography:
Wei-Kai, Chang, male, is a naive of Taiwan island. He was bron in 1987, entered Taipei Medical Univerisity, department of Medicine in 2006 and graduated in 2013. His post-graduate year resident in Veterans General Hospital Taipei. Since 2015, he is resident doctor in radaition oncology department of Koo Foundation Sun Yat-Sen Cancer Center.

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