Delayed emesis induced by moderately emetogenic chemotherapy: Do we need to treat all patients?

Background. The pattern and prognostic factors of delayed nausea an d vomiting induced by moderately emetogenic chemotherapy have not yet been adequately studied. Patients and methods. Data are derived from a large and well defined population of patients studied to evaluate the efficacy and tolerability of granisetron: dexamethasone and their combination in the control of acute emesis over repeated cycles of moderately emetogenic chemotherapy. Patients were monitored on days 2-5 without receiving any prophylactic treatment for delayed emesis. Results. There were 395 evaluable patients at the first, 352 at the second and 319 at the third cycle of chemotherapy. Overall, 32.7% patients suffered symptoms of delayed vomiting and/or moderate-severe nausea at the first, 32.1% at the second and 35.1% at the third cycle of chemotherapy. More precisely, the incidence of delayed vomiting was 21.3% at the first, 18.5% at the second and 21.0% at the third cycle of chemotherapy, while the incidence of delayed moderate-severe nausea was 25.1%, 25.0% and 26.0%, respectively. The incidence of delayed vomiting and moderate-severe nausea was very low in patients who obtained good control of acute vomiting and moderate-severe nausea, but it remained substantial in patients who experienced them during the first 24 hours after chemotherapy. In fact, at first/second/third cycle of chemotherapy delayed vomiting occurred in 12.3%/11.8%/ 13.1% of patients who did not suffer from acute vomiting and in 54.1%148.4%/55.9% of those who had acute vomiting, respectively. Similar data were obtained for delayed moderate-severe nausea. Conclusions. Patients without acute vomiting or moderate-severe acute nausea may not need any antiemetic prophylaxis for delayed vomiting or nausea, while those with a history of acute vomiting or moderate-severe acute nausea should always be treated for delayed emesis. Selection bias and dependence effect of delayed emesis on acute emesis can cause misinterpretation of data derived from clinical trials in patients submitted to multiple cycles of chemotherapy.