Racial and ethnic differences in capecitabine toxicity in patients with gastrointestinal tract cancers

BACKGROUND: Capecitabine is used as a first-line treatment for gastrointestinal (GI) tract cancers. Common toxicities of capecitabine include diarrhea and hand-foot syndrome, which frequently require dose reduction, interruption, or discontinuation. While racial and ethnic differences in capecitabine toxicities have been suggested, they have not been evaluated in a diverse “real-world” setting. We examined differences in capecitabine-related toxicities in different racial and ethnic populations. METHODS: The electronic medical records of patients receiving first-line capecitabine-containing regimens for GI malignancies were reviewed. Patients on irinotecan-containing regimens or radiation were excluded because of overlapping toxicities. Multiple logistic regression models were used to test the association between race or ethnicity and capecitabine toxicities while adjusting for other demographic characteristics. RESULTS: One hundred twenty-five patients diagnosed with colon (N=76, 60.8%), rectal (N=22, 17.6%), gastric (N=16, 12.8%), or other GI cancers (N=11, 8.8%) were included. In logistic regression analysis, diarrhea occurrence was significantly lower in the African-American/non-Hispanic (odds ratio [OR] 0.25, 95% confidence interval [CI] 0.08-0.75; P=0.01) compared to Caucasian non-Hispanic population. The occurrence of dose-reduction was significantly higher in the African-American/non-Hispanic population (OR 5.83, 95%CI 1.49-22.80; P=0.01) and in the Caucasian/Hispanic population (OR 4.49, 95%CI 1.09-18.42; P=0.03) compared to Caucasian non-Hispanic population. CONCLUSIONS: We have identified racial and ethnic differences in the incidence of capecitabine toxicities, which may help clinicians counsel patients with GI malignancies on capecitabine. There is a need for prospective studies to confirm our findings and to understand the relationship between the incidence of toxicities and dose reductions or discontinuation.