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 surgery and postmastectomy radiation therapy for high-risk breast cancer patients. The purpose of this study is to determine whether a delay in radiation therapy after mastectomy results in an increased risk of local-regional recurrence of breast cancer. MATERIALS AND METHODS: A retrospective review was performed of the University of Pennsylvania database of 221 patients with high-risk breast cancer treated with postmastectomy radiation therapy between 1977 and 1992. The surgery to postmastectomy radiation 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 patients (40%). Adjuvant chemotherapy was utilized in 151 patients (68%). The median follow-up was 4.3 years after postmastectomy radiation therapy. RESULTS: Because the three groups showed significant differences for a number of prognostic factors, outcomes are reported in terms of local-regional recurrence only and not survival. The actuarial rate of local-regional recurrence at 8 years was 13% for patients with a surgery to radiation therapy interval of 2 months or less, 4% for those with an interval of 2.1 to 6 months, and 12% for those with an interval of greater than 6 months. A similar analysis performed for 4 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.