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

PURPOSE: 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.

METHODS AND MATERIALS: 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.

RESULTS: 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).

CONCLUSIONS: 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.