Prescribed medications in survivors of adult-onset cancer in Norway: A register-based study

Introduction Cancer patient's survival has improved steadily in Europe during the past decades, mainly due to major changes in diagnostic work-up, treatment and follow-up of patients. Hence, the population of cancer survivors has increased. Increasing use of multimodal curative therapies and novel treatment options for advanced cancers may cause adverse health effects. Prescribed medications provide a comprehensive assessment of long-term health-related issues among cancer survivors. We conducted a registry-based study to explore long-term adverse health effects, using prescribed medications as a proxy of disease, in adult cancer patients surviving at least five years after diagnosis. Methods The entire Norwegian population, born in 1990 or earlier, alive per January 1, 2005, approximately 3.8 million individuals were defined as our study cohort. The individuals were followed-up by linking compulsory national registers; the National Registry, the Cancer Registry of Norway (1953–2014), and the Norwegian Prescription Database (since 2004). Five-year cancer survivors were identified and the proportions of medication use in cancer survivors and cancer-free populations was calculated. The proportions were standardized for age per January 1, 2005; categorized as 0–19, 20–39, 49–59, 60–79, and over 80 years of age. Incidence rates of prescribed medication will be estimated using Cox proportional hazard models. Preliminary results A total of 299,326 cancer survivors, born during 1896-1990, were identified (47% males). The largest group of cancer survivors among males were those with cancer of the prostate (35%), skin (13%), bladder (8%), colon (7%), testis (5%) and rectum (5%). Among females, the largest group of survivors were those with cancer of the breast (32%), skin (14%), colon (8%), corpus uteri (7%), cervix uteri (5%), and rectum (3%). The study identified differences between cancer survivors and the cancer-free population in the use of medications (proportions presented as percentages) for the digestive tract and metabolism (22% versus 16%, respectively), blood and blood-forming organs (24% versus 17%), cardiovascular system (39% versus 28%), genito-urinary system and sex hormones (10% versus 16%), nervous system (39% versus 32%), systemic hormones other than sex hormones and insulin (12% versus 9%), musculo-skeletal system (23% versus 27%), and anti-neoplastic and immune-modulating agents (7% versus 2%). In contrast, similar medication use were found for antiparasitic products, insecticides and repellents (3% in each group), anti-infectives (for systemic use) (∼ 26%), dermatological (∼ 13%), sensory organs (∼ 13%), and for respiratory system (∼ 22%). Conclusions Our preliminary findings indicate a higher use of various prescribed medications among cancer survivors compared with the cancer-free population. This could suggest increased health challenges among the cancer survivors. Optimized follow-up of cancer survivors as well as primary and secondary prevention strategies of major comorbidities are recommended. More specific analyses, both regarding type of cancer and medications, will be performed.