Diseases of renal function and bone metabolism after treatment for early onset cancer: A registry‐based study

Modern cancer therapy has led to a growing number of pediatric and young adult cancer survivors, who are prone to increased morbidities caused by the late effects of therapy. The aim of our study was to investigate pediatric and young adult cancer survivors' morbidity due to renal and bone metabolism diseases and especially to study bone metabolism in cancer survivors with renal disease. Patients were identified from the Finnish Cancer Registry, and the cohort consisted of 13,860, 5-year survivors of cancer diagnosed below the age of 35 years. Healthy siblings were used as the comparison cohort. Information on the main outcomes was linked from the national Care Register for Health Care. Hazard ratios (HRs) comparing cancer survivors to siblings were calculated for various outcomes. The patient cohort was separated into two age groups, pediatric (0-19 years) and young adults (20-34 years). Significantly elevated HRs (p < 0.0001) in survivors were observed in both age groups for scoliosis (HR 1.6, 95% confidence interval [CI] 1.3-2.0), osteoporosis (HR 5.2, 95% CI 2.4-11.4), osteonecrosis (HR 12.7, 95% CI 5.4-29.7), nephritis (HR 1.9, 95% CI 1.5-2.2) and kidney failure (HR 3.6, 95% CI 2.4-5.3) for all. For cancer survivors with a renal outcome, the risk for developing any outcome of bone metabolism was increased (HR 2.3, 95% CI 1.4-3.6). These results show that pediatric and young adult cancer survivors have an elevated risk for long-term, adverse outcomes related to renal function and bone metabolism. These results suggest follow-up care for young cancer patients.