The sequencing of radiation therapy and chemotherapy after mastectomy in premenopausal women with breast cancer.

Objective: The purpose of this study was to evaluate the prognostic importance of the sequencing of radiation therapy and chemotherapy after mastectomy in high-risk premenopausal women with breast cancer in addition to other known prognostic factors in the literature.

Methods: In this retrospective study, 176 premenopausal women with breast cancer were evaluated. The median age at referral was 39 years (range, 28-59 years); 106 patients had stage II and 70 had stage III disease. All were subjected to mastectomy. The median number of lymph nodes removed was 19. The influence of age, histological grade, number of nodes removed, number of positive nodes, tumor size, estrogen receptor status, lymphovascular invasion and sequencing of radiotherapy and chemotherapy on 5-year locoregional disease-free survival, 5-year systemic disease-free survival, 5-year disease-free survival and 5-year cancer-specific survival were studied.

Results: The 5-year locoregional disease-free survival was 94% for the entire patient population. Because of the small number of locoregional recurrences, none of the evaluated factors was prognostically significant for locoregional recurrence. The 5-year systemic disease-free, disease-free and cancer-specific survival rates were 72, 70 and 77%, respectively. On multivariate analysis of host, tumor and treatment-related factors, the number of positive nodes [RR 1.9 (95% CI: 1.36-2.63), RR 2 (1.46-2.84 ) and RR 1.8 (1.3-2.71), respectively], histopathological grade [RR 1.8 (95% CI: 1.24-2.65), RR 1.9 (1.34-2.88), RR 2.5 (1.65-4.07), respectively], estrogen receptor status [RR 3.5 (95% CI: 1.5-8.6), RR 3.9 (1.64-9.41), RR 2.5 (1.05-6.24), respectively] and the sequencing of radiotherapy and chemotherapy [RR 1.6 (95% CI: 1.17-2.39), RR 1.7 (1.25-2.54), RR 1.6 (1.14-2.43), respectively] were all significant independent predictors of outcome.

Conclusions: Our results show that in addition to traditional prognostic factors, the sequencing of radiation therapy and chemotherapy also predict for increased risk of any type of recurrence or further tumor death.