Purpose: To evaluate the effectiveness of prophylactic dexamethasone for the control of radiation induced emesis (RIE) when added to ondansetron during days 1 to 5 of fractionated radiotherapy. The study had two hypotheses: ondansetron and dexamethasone could provide superior control of RIE over ondansetron alone during the prophylactic period and; the combination could provide sustained control of RIE during subsequent fractions of radiotherapy.
Patients and methods: Between May 2001 to Jan 2004, 211 patients receiving radiotherapy (> or = 15 fractions) to the upper abdomen were randomly assigned to receive ondansetron 8 mg bid with either dexamethasone 4 mg daily or placebo during fractions 1 to 5. Rescue antiemetics were provided.
Results: During the prophylactic period there was a trend for improved complete control of nausea in the dexamethasone arm (50% v 38%; P = .06) while complete and partial control of emesis, average nausea score, and use of rescue medications were similar in the two groups. During the overall study period patients receiving dexamethasone had better complete control of emesis (23% v 12%; P = .02) and a lower average nausea score (0.28 v 0.39; P = .03); there was a trend towards less use of rescue medications with dexamethasone (70% v 80%; P = .09); other outcomes were similar on the two arms. Quality of life analysis showed a significant difference in appetite.
Conclusion: The addition of dexamethasone to ondansetron as prophylaxis provides a modest improvement in protection against RIE during moderately emetogenic fractionated radiotherapy. It is a potentially useful addition to 5-hydroxytryptamine-3 receptor antagonists in this setting.