Dorsal vagal complex of the brainstem: conformal avoidance to reduce nausea.

Abstract

To investigate the role of dose to the dorsal vagal complex (DVC) as an emetic stimulus in head-and-neck cancer patients treated with intensity modulated radiation therapy but without chemotherapy. Seventy consecutively treated patients were analyzed for factors associated with nausea. The DVC was contoured on treatment planning scans using a previously published template and mean dose to the structure was analyzed for dose response. Nausea occurred in 26 of 70 patients (37%). Two patients (3%) experienced grade 2 nausea, with the remainder having grade 1 nausea. On univariate analysis, dose to the DVC, age, and T-stage were the only significant predictors of nausea. The highest quartile of dose to the DVC (>3000 cGy) was associated with an incidence of nausea of 67% compared with less than 30% in each of the other 3 quartiles (P = .0255). Dose to the DVC of the brainstem appears to correlate with radiation-induced nausea and vomiting. Attentive treatment planning efforts can reduce dose to this critical structure and hopefully minimize the risk of nausea.