The Role of a Boost Radiation Dose in Patients with Negative Re-Excision Findings

Abstract

The aim of this study is to evaluate whether patients who have no residual tumor at the time of a re-excision lumpectomy benefit from the addition of a radiation boost dose. The records of 535 patients treated with breast- conserving therapy (BCT) for Stage I-II breast cancer were reviewed. The actuarial risk of local recurrence (LR) was determined for the 262 patients in this cohort who underwent re-excision lumpectomy. There was no significant difference in the 10-year freedom from local recurrence (FFLR) for patients with negative re-excisions (96%) compared to patients with residual tumor that was adequately excised (92%). Patients with residual tumor at or close to the final margins, however, had a significantly lower FFLR (80%; p=.01). The FFLR for patients with negative re-excisions was 97% for patients not receiving a boost (n=94) and 95% for patients who received a boost (n=74) (p=ns). For patients <50, FFLR was 96% with a boost and 87% without a boost (p=ns). Extensive intraductal component was the only significant predictor of LR among patients with negative re-excisions (p=.02). The presence of residual disease in the re-excision specimen did not predict for LR as long as the final margins were negative. Among patients with negative re-excisions, the boost did not significantly improve local control. There was a trend for better outcomes, however, in younger patients treated with a boost even in the setting of a negative re-excision. Due to the limitations of the retrospective nature of this study, it will be important to address this question in a prospective fashion before making any definitive conclusions or changes in current clinical practice.