Patterns of Prescription Medication Use Before Diagnosis of Early Age-Onset Colorectal Cancer: Population-Based Descriptive Study (Preprint)

Abstract

BACKGROUND Colorectal cancer (CRC) is estimated to be the fourth major cancer diagnosis in Canada (except for non-melanoma skin cancers) and the second and third leading cause of cancer-related death in males and females, respectively. OBJECTIVE The rising incidence of early age-onset colorectal cancer (EAO-CRC; diagnosis at <50 years), calls for better understanding of patients’ pathway to diagnosis. We evaluated patterns of prescription medication use before EAO-CRC diagnosis. METHODS We used linked administrative health databases in British Columbia, Canada to identify cases diagnosed with EAO-CRC between 01/01/2010 to 12/31/2016, along with cancer-free controls (1:10), matched on age and sex. We identified all prescriptions dispensed from community pharmacies during the year prior to diagnosis and used the Anatomical Therapeutic Chemical (ATC) Classification system Level 3 to group prescriptions according to drug class. We conducted a parallel assessment for those diagnosed with average age-onset CRC (AAO-CRC; diagnosis at age ≥50 year). RESULTS We included 1,001 EAO-CRC cases (41.0 ± 6.1 years; 45% females), 12,989 prescriptions were filled in the year before diagnosis by 797 individuals (79.7%). Top filled drugs were antidepressants (1st; 13.1%). Drugs for peptic ulcer disease and gastroesophageal reflux disease (3rd; 6.1%) were more likely filled by EAO-CRC cases than controls (OR 1.4, 95% CI, 1.2 to 1.7) and with more frequent fills (OR 1.8, 95% CI, 1.7 to 1.9). We noted similar patterns for topical agents for hemorrhoids and anal fissures which were more likely filled by EAO-CRC cases than controls (OR 7.4, 95% CI, 5.8 to 9.4) and with more frequent fills (OR 15.6, 95% CI, 13.1 to 18.6). CONCLUSIONS We observed frequent prescription medication use in the year before diagnosis of EAO-CRC, including for drugs to treat commonly reported symptoms of EAO-CRC.