Incidence of Radiation-induced Nausea and Vomiting: A Prospective Single-institution Pilot Study.

Radiation-induced nausea and vomiting (RINV) is a frequent adverse event that occurs in patients undergoing radiotherapy. However, research on RINV is underrepresented. This prospective single-institution exploratory pilot study investigated the incidence of RINV according to the irradiation site and observed the efficacy of symptomatic antiemetic treatment in controlling symptoms of RINV. The primary outcomes were the proportions of emesis-free days and nausea-free days. The secondary endpoints included the time to the first episode of RINV, frequency of vomiting, and severity of nausea, including its impact on eating habits and weight loss. Fifteen patients were enrolled in each group (minimal, low, and moderate emetogenic risk). All patients received greater than 20 Gy in five fractions. Evaluation was based on weekly questionnaires completed by patients during routine clinic visits. Nausea and vomiting occurred in 11 and 0 patients, respectively. Six of 15 patients in the minimal-risk group, 1 in the low-risk group, and 4 in the moderate-risk group experienced nausea. Although all 11 symptomatic patients were offered antiemetics, only 3 used them, who reported satisfactory control of nausea. The percentage of emesis-free days for all patients was 100% and the percentage of nausea-free days for the 11 patients who developed RINV was 38%. An unexpectedly high percentage of patients in the minimal-risk group experienced nausea; all had breast cancer. Future studies should investigate factors beyond the irradiation site, including the characteristics of the patient and the treatment, to better predict an individual's risk of RINV.