Prescription rates for commonly used drugs before and after a prostate cancer diagnosis

Purpose: To investigate differences in prescription rates of commonly used drugs among prostate cancer patients and cancer-free comparisons and between patients diagnosed with localized and non-localized disease. Methods: We conducted a register-based study including all men aged 50–85 years diagnosed with prostate cancer in Denmark from 1998 to 2015 and an age-matched cancer-free comparison cohort. We calculated the number of new and total prescriptions from three years before to three years after the date of diagnosis of the case for selected drug classes divided by the number of person-months and stratified by stage at diagnosis. Results: We included 54,286 prostate cancer patients and 249,645 matched comparisons. 30,712 patients were diagnosed with localized disease and 12,884 with non-localized disease. The rates of new prescriptions increased considerably among patients within the year before the diagnosis. Hereafter the rates varied between drug classes. For most drug classes, total prescription rates for patients and comparisons increased similarly in the study period. Total prescription rates varied between men with localized and non-localized disease for all drug classes apart from statins. Conclusion: Our findings indicate that a large proportion of prostate cancer cases are likely diagnosed during medical work-up for other reasons than prostate cancer. Increased rates occur within the last year before diagnosis and future studies on the interaction between drug use and prostate cancer should at least include a one year pre-diagnostic lag-time. Post-diagnostic prescription rates demonstrated an increased use of drugs most likely associated with the consequences of the disease.