Local Failure and Acute Radiodermatological Toxicity in Patients Undergoing Radiotherapy With and Without Post-Mastectomy Chest Wall Bolus: Is Bolus Ever Necessary?

Publication date: Available online 30 October 2016
Source:Practical Radiation Oncology
Author(s): Stephen Abel, Paul Renz, Mark Trombetta, Michael Cowher, E D Werts, Thomas B Julian, Rodney Wegner
PurposePost-mastectomy chest wall radiotherapy has historically used bolus to increase dose at the skin surface. Despite the theoretical benefits of bolus, the clinical implications of locoregional tumor control, cosmesis, and the incidence of radiodermatitis, are less well characterized. We hypothesized that treatment in the presence or absence of bolus results in equivalent chest wall recurrence rates but its presence results in more severe acute dermatologic toxicity.Methods and MaterialsLocally advanced breast cancer patients undergoing chest wall radiotherapy were retrospectively reviewed from 2005–2015 (n=106; 53 with bolus, 53 without). Outcomes including local failure, acute skin toxicity, and treatment interruptions were recorded.Median age was 59years (range 28–91) and median follow-up was 34months. Histology was invasive ductal carcinoma (73%), invasive lobular carcinoma (20%), inflammatory (6%) and neuroendocrine (1%). Fifty-nine percent were T3/T4 primary tumors and 29.2% had clinical/pathologic skin involvement. Node positive patients accounted for 80.2%. Chemotherapy was administered in 84.0%. All patients had 3-D conformal radiotherapy and received a median dose of 61Gy (range 50–63Gy).ResultsLocal failure was 6.6% (n=7) overall, with four failures in the bolus group and three in the no bolus group. No pathological factors were associated with local failure. Acute grade 2 and 3 skin toxicities (37 versus 22), and treatment interruptions (20 versus 3) were more common in the bolus group (p<0.05). Mean treatment interruption (14.5 versus 5days) was longer for patients receiving bolus. Patients undergoing treatment interruption were more likely to fail locally than patients not requiring a treatment interruption (17.4% versus 3.6%, p=0.0322).ConclusionsBolus omission in adjuvant chest wall radiotherapy may be a reasonable approach to avoid acute skin toxicity and treatment interruptions while preserving local control, however, further study will be needed to reach a definitive conclusion.



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