Technique and outcome of post-mastectomy adjuvant chest wall radiotherapy-the role of tissue-equivalent bolus in reducing risk of local recurrence.

Abstract

Adjuvant chest wall radiotherapy is used in patients with high-risk histological features post-mastectomy to reduce the risk of locoregional recurrence. Treatment can be given with or without a tissue-equivalent bolus to increase skin surface dose. The additional benefit of using a bolus remains unclear; however, it is known to be associated with a higher incidence of skin toxicity. This study compared chest wall recurrence and skin toxicity in patients treated with and without a bolus. This retrospective cohort study reviewed 314 consecutive patients who received chest wall radiotherapy between 2005 and 2010. Data were collected on histological, demographic and treatment parameters and on the incidence and grade of acute skin reactions. Treatment outcomes analyzed included chest wall recurrence, disease-free survival and overall survival (OS). 101 patients received treatment with a bolus; 213 patients received treatment without a bolus. A significantly higher incidence of acute skin toxicity was seen in the bolus treatment group (p = 0.002). One patient treated with a bolus developed chest wall recurrence compared with four patients treated without a bolus. No statistically significant difference could be shown between the two groups. 66 (21%) patients had metastatic relapse. Median time to relapse was 29.5 months and OS was 76% in both treatment groups. No statistically significant difference in chest wall recurrence can be demonstrated between patients treated with and without a bolus. This study is consistent with limited previous literature and invites further evaluation of the role of a bolus in post-mastectomy chest wall radiotherapy, especially considering the increased toxicity that the use of a bolus generates.