Abstract
Background/Aims Convenient for its oral route of administration, capecitabine is increasingly used in the older population with colorectal and other solid tumors. Since renal impairment increases with age, we designed a pilot study to assess adherence to standard dose reductions for renal insufficiency and dosing recommendations for older patients. We sought to describe patterns of capecitabine use in older patients and factors that influence dosing; specifically age and renal insufficiency.
Methods Tumor registries of 8 community-based outpatient cancer clinics were reviewed to identify patients age 65 and older treated for breast, colon, esophageal, pancreas or stomach cancers from 01/01/2001–12/31/2012. Of the 1403 patients identified, 53 received capecitabine. A retrospective electronic medical record review was conducted to collect capecitabine dose and demographic variables, vital signs, adverse events, hospitalizations, and clinical and laboratory data.
Results Of the 53 patients who received capecitabine, 21% received a dose appropriate for documented age and renal function. Most patients received doses lower than recommended and, on average, were under-dosed by 25%. Univariate analysis showed women were under-dosed more frequently than men, 85% vs. 55%. Multivariate analysis showed lower than recommended capecitabine dosing for patients with a diagnosis other than colorectal cancer −481 (95%CI −807,−154; P = 0.01) and Stage II and III disease −331 (95%CI −646,−16; P = 0.05).
Conclusions This pilot study suggests that a disparity exists in the dosing of capecitabine in older patients and both men and women received empiric doses of capecitabine below those recommended for renal insufficiency or age. This may be of particular importance in the adjuvant setting, where under-dosing may compromise outcome. Our findings highlight the need for a more thorough understanding of how chemotherapeutic agents are prescribed for older patients with cancer.
