Potential medication problems in older newly diagnosed cancer patients in Canada during cancer treatment: a prospective pilot cohort study.

INTRODUCTION: Older cancer patients are possibly at an increased risk of medication-related problems because, typically, they receive many medications during their cancer treatment, both for the cancer itself and for supportive care.
OBJECTIVES: The aim of this study was to describe the number and severity of potential medication problems during treatment of cancer in the first year after diagnosis. We also sought to examine whether patients receiving systemic cancer treatment had more medication-related problems at 3, 6 and 12 months than those not receiving systemic cancer treatment.
METHODS: This was a prospective pilot cohort study on health and vulnerability in older newly diagnosed cancer patients with 1-year follow-up. The study was conducted at Segal Cancer Centre, Jewish General Hospital, Montreal, Canada. Of 156 eligible patients, 112 agreed to participate (response 71.8%). The patients were aged >or=65 years and were newly diagnosed with breast, colorectal or lung cancer, lymphoma or multiple myeloma. Patients were asked for permission to obtain their list of medications from their pharmacist. The cancer treatment information was abstracted from the medical chart. Vigilance Santé software was used to identify the presence, type and severity of potential medication problems.
RESULTS: The median number of medications was five at baseline, seven at 3 months and six at 6 and 12 months. At baseline, 247 potential medication problems were identified, followed by 273 at 3 months, 229 at 6 months and 188 at 12 months. About half of the patients at each follow-up had one or more moderate or severe potential medication problem. Patients receiving systemic cancer treatment had significantly fewer potential problems at 3 months than patients not receiving systemic cancer treatment, but no differences were observed at 6 and 12 months. The most common warnings were contraindications, interactions and miscellaneous warnings, and the cancer treatment was involved in 12% of all potential problems.
CONCLUSION: This study showed that the majority of older newly diagnosed cancer patients take prescribed medication and about two-thirds have potential medication problems, of which about half are of at least moderate severity. The cancer treatment was involved in only a small proportion of all potential drug problems.