Abstract P3-07-06: Survival benefit increases after breast conserving therapy compared to mastectomy when axillary node status is positive in early stage breast cancer: A registry based follow-up study of Norwegian women with screening and interval detected breast cancer pr

Abstract

Abstract BACKGROUND: Recent register studies on early stage breast cancer have shown better survival when women underwent breast-conserving treatment (BCT) compared to mastectomy (MTX). It is unclear if this is due to selection effects or to a systemic benefit of BCT compared to MTX. If there is a systemic benefit this could theoretically be more prominent in some subgroups of breast cancer. The aim of this study is to evaluate if there are any subgroups with early stage breast cancer that benefits more of BCT compared to MTX. METHOD: A cohort of 6.629 women aged 50-69 with primary operable breast cancer detected in the screening programme (on screening or between screening, interval cancer) were selected from January 1998 until December 2009 and followed up until end of 2010. Life tables for overall survival (OS) and breast cancer specific survival (BCSS) were calculated in surgery groups and stages. Corresponding Kaplan-Meier plots were stratified in T1N1M0 and Ductal Carcinoma. OS and BCSS were compared using Cox proportional hazard for estimating hazard ratio between BCT and MTX in crude and adjusted analysis. RESULTS: 5-years BCSS in T1N0M0 was 99% for both surgical cohorts (BCT and MTX). 5-years BCSS in T1N1M0 was 98% for women undergoing BCT and 91% for women undergoing MTX. Respectively, 10-years BCSS in T1N1M0 was 96% for women undergoing BCT and 83% for women undergoing MTX. In adjusted analysis, HR for breast cancer death for women with stage T1N1M0 undergoing MTX compared to BCT was 3.12 (95% CI: 1.71-5.72). Respectively, 3.67 (95% CI: 1.20-11.22) stratified on grade III and 4.89 (67 (95% CI: 1.25-19.01) stratified on hormone receptor negative disease. CONCLUSION: The benefit of BCT compared to MTX seems to increase with increasing severity of the breast cancer disease, positive nodal status (N1), grade III and hormone receptor negative disease. These finding indicate a systemic benefit of BCT compared to MTX. Citation Format: Olaf Johan Hartmann-Johnsen, Ellen Schlichting, Rolf Kaaresen, Jan Franz Nygaard. Survival benefit increases after breast conserving therapy compared to mastectomy when axillary node status is positive in early stage breast cancer: A registry based follow-up study of Norwegian women with screening and interval detected breast cancer pr [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-06.