Abstract
PURPOSE: This register-based study investigates the probability of a livebirth after cancer during the female reproductive age. METHODS: The study population, derived from the DANAC II cohort, included women aged 18-39 diagnosed with cancer between 1978 and 2016, matched with 60 undiagnosed women each from the general population. Primary outcome was a livebirth after cancer with follow-up until death, emigration, or end of follow-up. Hazard ratios (HR) were calculated using multivariable Cox regression analyses. RESULTS: The population included 21,596 women with cancer and 1,295,760 without. The 20-year cumulative incidence of livebirth after cancer/study entry was lower among women with cancer (0.22 [95% CI 0.22-0.22]) compared to those without (0.34 [95% CI 0.34-0.34]). The HR of a livebirth after cancer was 0.61 [95% CI 0.59-0.63]; highest at age 18-25 (HR = 0.72 [95% CI 0.68-0.76]); and lowest at age 33-39 (HR = 0.50 [95% CI 0.47-0.54]). Nullipara women had higher HR of a livebirth than those with children (HR = 0.72 [95% CI 0.69-0.75] vs. HR = 0.48 [95% CI 0.46-0.51]). HR was lowest for women with breast, gynecological, central-nerve-system cancer, and leukemia. Women with/without cancer were comparable in assisted reproductive technology initiation after cancer/study entry, but HR was higher among nullipara than in those with prior children. CONCLUSIONS: Cancer during reproductive years significantly and negatively impacts HR of a livebirth after cancer, particularly as age at diagnosis increases. Low HR of livebirth is observed in specific cancer groups. IMPLICATIONS FOR CANCER SURVIVORS: Results underscore the importance of oncofertility counseling at diagnosis, referral to fertility specialist before treatment, and follow-up after cancer, focusing on cancer type, parity status, and age at diagnosis.