Prescribed drugs in 27 000 individuals after diagnosis of colorectal cancer: A population-based cohort study.

BACKGROUND: The prevalence of prescribed drugs in survivors of colorectal cancer (CRC) was evaluated. METHODS: Data from the Cancer Registry of Norway were linked to the Norwegian Prescription Database for a study population of 3.52 million individuals. Prevalence ratios (PRs) with 95% confidence intervals (CIs) of prescribed drugs in CRC-survivors compared to the cancer-free population, were estimated by log-binomial regression, adjusting for age and education. RESULTS: Almost 27 000 individuals, aged 20 to 84, were diagnosed with CRC during 2005 to 2014. The first year after diagnosis, the prevalence of prescribed drugs was higher in CRC-survivors compared with the cancer-free population, especially drugs for anxiety and tension, and steroid-responsive conditions. PRs for several drugs, especially drugs used for mental and behavioural disorders, decreased with time since diagnosis. The prevalence of drugs used for anxiety and tension was elevated 10 years after diagnosis; PRs the first year after diagnosis were 20 (95% CI: 18-22) in males and 17 (16-18) in females. Ten years after diagnosis PRs were 5.0 (3.1-7.9) and 2.0 (1.0-3.8), respectively. In absolute numbers, the largest increase, compared to the cancer-free population, was in drugs used for gastric acid disorders and pain. The prevalence of neuromodulatory drugs was higher in CRC-survivors. CONCLUSIONS: The prevalence of several drugs was higher in CRC-survivors than in the cancer-free population 10 years after diagnosis. The largest absolute excess in prevalence was for gastric acid disorder and pain medications, while the relative prevalence of drugs used for anxiety and tension was high in CRC-survivors. Long persisting neuropathia was indicated.