Incidence and predictors of chest wall toxicity after high-dose radiation therapy in 15 fractions

Purpose: Fifteen fraction treatment schedules are increasingly used to deliver high doses of radiation therapy (RT) to both lung and hepatobiliary malignancies. The purpose of our study was to examine the incidence and predictors of chest wall (CW) toxicity in patients treated with this regimen.

Methods and materials: We evaluated 135 patients treated with RT to doses ≥52.5 Gy in 15 fractions for thoracic and hepatobiliary malignancies between January 2009 and December 2012. We documented patient characteristics and CW dosimetric parameters for each case. Toxicity was scored using the Common Terminology Criteria for Adverse Events, version 4.0, criteria for radiation dermatitis and CW pain. Patient characteristics and CW dosimetric parameters were evaluated for their association with CW toxicity using proportional hazards regression.

Results: Median follow-up was 9 months from the start of RT. Forty-eight patients (36%) developed dermatitis at a median time of 18 days. In multivariable analysis, the absolute volume of CW (in cm³) receiving 40 Gy (V40) ≥120 cm³ was associated with the occurrence of dermatitis (hazard ratio, 3.12; 95% confidence interval, 1.74-5.60; P < .001). Twenty-one patients (16%) developed CW pain (20 grade 1, 1 grade 2) at a median time of 3 months. In multivariable analysis, CW V40 ≥150 cm³ was associated with the occurrence of CW pain (hazard ratio, 2.65; 95% confidence interval, 1.12-6.24; P = .03). The absolute rate of CW pain in patients with V40 <150 cm³ was 11% versus 26% in patients with V40 ≥150 cm³ (P = .03).

Conclusions: Hypofractionated RT with 15 fraction regimens results in an acceptable incidence of CW toxicity, specifically CW pain. We recommend a dose constraint of V40 <150 cm³ to minimize this adverse event.