Goals of work: A number of prognostic factors have been identified as risk factors for chemotherapy-induced emesis. This post-hoc analysis addressed whether: (1) these prognostic factors can identify a low-risk group for whom ondansetron plus dexamethasone alone provide a high level of protection (≥80% no emesis); (2) the NK1 receptor antagonist aprepitant improves antiemetic outcome regardless of emetic risk.
Patients and methods: Breast cancer patients in a phase III double-blind, placebo-controlled trial were randomized to antiemetic regimens including ondansetron and dexamethasone, or aprepitant, ondansetron, and dexamethasone. Multivariate logistic regression models were used to assess the impact on emesis (but not nausea) of the regimen with aprepitant, and previously reported risk factors, including age (<55 and ≥55 years), ethanol use (0-4 or ≥5 drinks/week), history of pregnancy-related morning sickness, and history of motion sickness, using a modified intent-to-treat approach.
Results: Treatment with aprepitant (P < 0.0001), older age (P = 0.006), ethanol use (P = 0.0048), and no history of morning sickness (P = 0.0007) were all significantly associated with reduced likelihood of emesis. The proportion of patients with one, two, or three risk factors who remained emesis free was significantly higher with the aprepitant-containing regimen than with the active control (70.2-82.8% vs. 38.6-66.4%, respectively).
Conclusions: Aprepitant markedly improved control of emesis in patients with one or more risk factors. This analysis did not support using risk factors for modifying the antiemetic approach. A low-risk group with zero risk factors for whom aprepitant provided little benefit was of questionable clinical utility, since they comprised less than 3% of patients.