Vahid Ghavami - Department of Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran
Saeedeh Hajebi Khaniki - Student Research Committee, Department of Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran
Fatemeh Homaei Shandiz - Department of Radiotherapy-Oncology, Omid and Ghaem Hospitals, Mashhad University of Medical Sciences, Mashhad, Iran
Nooshin Akbari Sharak - Student Research Committee, Department of Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran

Background: Survival after breast conserving surgery (BCS) vs. modified radical mastectomy (MRM) is a controversial issue. In this study, we want to compare the disease-free survival (DFS) of women who underwent BCS with those treated by MRM.Method: In this historical cohort study, a total of ۱۰۹۷ women who were diagnosed with breast cancer between ۲۰۰۱ and ۲۰۰۷ and received modified MRM or BCS were entered into the study and followed up to March ۲۰۱۷. Kaplan-Meier estimator and extended cox model, and Cox proportional hazards model with propensity score weighting were implemented to compare overall survival between two groups.Results: A total of ۲۸۳ women with a maximum follow-up of ۱۱.۱ years and age ۴۷.۱۷ ± ۱۱.۲۷۸ were met the inclusion criteria. The results of the extended cox model did not show any difference between the survival of two groups (P = ۰.۳۵). After implementing the Cox model with propensity score weighting, the inferences remained unchanged (P = ۰.۶۷).Conclusion: The patients treated with BCS tend to have the same DFS rate as those who underwent a mastectomy in a randomized controlled trial-like setting using propensity score weighting.

Inverse probability of treatment weighting (IPTW), Breast neoplasms, Mastectomy, Modified radical, Segmental mastectomy