Predictors of brachial plexopathy following head and neck reirradiation
Khaled Dibs1, Emile Gogineni1, Eric Cochran1
1Department of Radiation Oncology, The Ohio State University Wexner Medical Center, United States.
Background And Purpose:
Reirradiation for recurrent or second primary head and neck cancer (HNC) can result in radiation-induced brachial plexopathy (RIBP), a debilitating side effect. This study aims to identify factors associated with the development of RIBP in patients undergoing reirradiation for recurrent or second primary HNC.
Materials And Methods:
This retrospective cohort study included 48 patients treated from 2015 to 2022 at a single National Cancer Institute-Designated Comprehensive Cancer Center, with a median follow-up duration of 22.7 months post-reirradiation. Patients underwent conventionally fractionated reirradiation, and a total of 72 brachial plexi that received overlapping courses of radiation were analyzed. Primary outcomes measured were the incidence of RIBP and factors contributing to increased risk, including EQD2 (equivalent dose in 2 Gy fractions) maximum point dose (Dmax, defined as 0.03 cc) and volumetric brachial plexus (BP) dosimetric endpoints (V80-V120), comorbidities, time between radiation courses, receipt of systemic therapy, and neck dissection. BP EQD2 was calculated using an alpha/beta of 3 Gy.
Results:
The crude incidence of RIBP was 23 %, occurring at a median of 9.5 months after reirradiation, with 12- and 24-month rates of 11 % and 16 %, respectively. On univariate analysis, concurrent cisplatin during the second course of radiation (hazard ratio [HR] 9.04, 95 % confidence interval [CI]: 2.70-30.40, p < 0.001) and cumulative EQD2 BP Dmax ≥ 103 Gy2 (HR 1.10, CI: 1.04-1.17, p < 0.001) were significantly associated with RIBP. These factors remained significant on multivariable analysis. RIBP incidence was significantly associated with all cumulative volumetric BP endpoints from V80-V120, with higher RIBP rates for V80 ≥ 1.94 cc, V100 ≥ 1.35 cc, V120 ≥ 0.89 cc, and EQD2 Dmax ≥ 103 Gy2.
Conclusions:
This study, the largest to date investigating rates of RIBP in patients with HNC treated with conventionally fractionated reirradiation, found that cumulative EQD2 maximum dose, and the use of concurrent cisplatin during the second RT course, were associated with increased rates of RIBP. Understanding these factors may guide clinicians in the setting of reirradiation, potentially leading to improved patient outcomes.
