Identification of a novel marker associated with risk for delayed chemotherapy-induced vomiting.

Purpose: Besides chemotherapy drugs, a number of patient-related factors (i.e., gender, age, history of alcohol consumption, and/or motion sickness) may be used to calculate the risk for chemotherapy-induced vomiting. We evaluated data with the intent of identifying a unique variable associated with delayed vomiting in patients receiving moderately emetogenic chemotherapy (MEC).

Methods: From an ongoing research study, the serotonin metabolite, 5-hydroxyindole acetic acid (5-HIAA), creatinine, and substance P were measured over a 72-h period in 25 patients receiving MEC. All patients were treated with a 5-hydroxytryptamine-3 receptor antagonist plus dexamethasone according to published guidelines; none received aprepitant prophylactically. Urine 5-HIAA/creatinine and serum substance P values were grouped according to the development (+) or absence (-) of delayed emesis. Baseline mean values associated with the two neurotransmitters were analyzed by analysis of variance.

Results: Eleven patients developed moderate to severe delayed vomiting; the other 14 were symptom-free. The pretreatment log (mean 5-HIAA/creatinine) was 1.22 and 1.81 in the (+) and (-) emesis groups, respectively, p = 0.0049; the pretreatment log (mean substance P) for the same respective groups was 5.33 and 4.09 pg/mL, p > 0.05. The log (mean ratio of substance P to 5-HIAA/creatinine) between-group difference in those with and without emesis was 4.53 and 2.52, respectively, p = 0.0002. The 5-HIAA/creatinine and ratio of substance P to 5-HIAA/creatinine data were also used to determine cutoff points which resulted in the optimal predictive accuracy.

Conclusions: These preliminary findings suggest that an elevated pretreatment ratio of substance P to 5-HIAA/creatinine >70 is associated with the development of delayed vomiting induced by MEC.