Analysis of outcomes for high-risk breast cancer based on interval from surgery to postmastectomy radiation therapy

PURPOSE The success of adjuvant chemotherapy has prolonged the interval between sur gery and postmastectomy radiation therapy for highrisk breast cancer patien ts. The purpose of this study is to determine whether a delay in radiation therapy after mastectomy results in an increased risk of local-regional rec urrence of breast cancer. MATERIALS AND METHODS A retrospective review was performed of the University of Pennsylvania data base of 221 patients with high-risk breast cancer treated with postmastecto my radiation therapy between 1977 and 1992. The surgery to postmastectomy r adiation therapy time interval was 2 months or less in 82 patients (37%), 2 .1 to 6 months in 50 patients (23%), and greater than 6 months in 89 patien ts (40%), Adjuvant chemotherapy was utilized in 151 patients (68%). The med ian follow-up was 4.3 years after postmastectomy radiation therapy. RESULTS Because the three groups showed significant differences for a numbe r of prognostic factors, outcomes are reported in terms of local-regional r ecurrence only and not survival. The actuarial rate of local-regional recur rence at 8 years was 13% for patients with a surgery to radiation therapy i nterval of 2 months or less, 4% for those with an interval of 2.1 to 6 mont hs, and 12% for those with an interval of greater than 6 months. A similar analysis performed for months or less versus greater than 4 months between surgery and postmastectomy radiation therapy showed no difference in local- regional recurrence (11% versus 10%, respectively). CONCLUSIONS A delay in the institution of postmastectomy radiation therapy in favor of the prolongation of chemotherapy for high-risk breast cancer patients does not adversely affect outcome for local-regional recurrence at 8 years. (Can cer J 2000;6:324-330).