Comparison of clinical outcome of breast cancer patients with T1-2 tumor and one to three positive nodes with or without postmastectomy radiation therapy

The value of postmastectomy radiation therapy for breast cancer patients with T1-2 tumor and one to three positive nodes remains controversial. The purpose of this retrospective study was to compare the clinical outcomes of breast cancer patients with T1-2 and one to three positive nodes with and without postmastectomy radiation therapy. Between May 1990 and June 2008, of 318 breast cancer patients with T1-2 and one to three positive nodes who had undergone modified radical mastectomy, 163 received postmastectomy radiation therapy and 155 did not. The clinico-pathologic characteristics were analyzed for clinical outcomes including loco-regional recurrence, distant metastasis, disease-free survival and overall survival. During the median follow-up period of 102 months, the clinical outcomes in postmastectomy radiation therapy versus no-postmastectomy radiation therapy groups were as follows: loco-regional recurrence rate (3.1 versus 11.0%, P=0.006); distant metastasis rate (20.9 versus 27.7%, P=0.152); 10-year disease-free survival rate (73.8 versus 61.3%, P=0.001); and 10-year overall survival rate (82.1 versus 76.1%, P=0.239). Through a multivariate analysis, a positive nodal ratio of ≥25% (hazard ratio=4.571, P=0.003) and positive lymphovascular invasion (hazard ratio=2.738, P=0.028) were found to be independent poor prognostic predictors of loco-regional recurrence. The reduction in loco-regional recurrence (hazard ratio=0.208, P=0.004) by postmastectomy radiation therapy was found to be significant. On the basis of our results, postmastectomy radiation therapy is highly recommended for breast cancer patients with T1-2 and one to three positive nodes, especially for high-risk subgroups with a positive nodal ratio of ≥25% and positive lymphovascular invasion, not only for reducing loco-regional recurrence but also for improving disease-free survival. (author)