Pathophysiology, severity, pattern, and risk factors for carboplatin-induced emesis

Carboplatin has proven efficacy in the treatment of ovarian cancer and has been proven to be less toxic compared to the parent compound cisplatin. Nevertheless, emesis is still a major problem associated with carboplatin-containing chemotherapy. Several investigators have focussed on the understanding of the pathophysiology and pattern of cisplatin-induced emesis. Data describing both the pathomechanisms and pattern of carboplatin-induced emesis are still lacking. This paper combines data from the literature with our own experience with the pattern and control of carboplatin-induced emesis, and presents data contributing to the understanding of the underlying pathomechanisms. Carboplatin induces a significant increase in urinary 5-HIAA excretion, the main metabolite of serotonin. 5-HIAA excretion levels remain elevated over 3 days following chemotherapy. Carboplatin-induced emesis is observed in about 40% of patients despite anti-emetic prophylaxis with 5-HT3 antagonists. Vomiting after carboplatin extends over days 1-3 with an equal distribution regarding the severity on each day. Analysis of the pattern of emesis revealed that delayed emesis (> 24 h after chemotherapy) is a major problem associated with carboplatin therapy. Description of the pattern of emesis as 'prolonged emesis' seems to be appropriate. 5-HT3 receptor antagonists such as ondansetron seem to be efficacious both in the control of acute and prolonged emesis following carboplatin chemotherapy, but randomly controlled data comparing ondansetron with other anti-emetic regimens have not yet been published. Univariate analysis reveals gender and combination therapy containing carboplatin and cyclophosphamide and/or anthracyclines as risk factors for emesis.