A prospective cohort study of infertility and cancer incidence

Objective: To investigate the association between infertility and the incidence of invasive cancer.Design: Prospective cohort study (1989-2015).Setting: Not applicable.Patient(s): A total of 103,080 women aged 25-42 years in the Nurses' Health Study II who were cancer-free at baseline (1989). Intervention(s): The infertility status (failure to conceive after 1 year of regular, unprotected sex) and causes of infertility were self-reported at baseline and biennial follow-up questionnaires.Main Outcome Measure(s): Cancer diagnosis was confirmed through medical record review and classified as obesity-related (colorectal, gallbladder, kidney, multiple myeloma, thyroid, pancreatic, esophageal, gastric, liver, endometrial, ovarian, and postmenopausal breast) or non-obesity-related (all other cancers). We fit the Cox proportional-hazards models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of the association between infertility and cancer incidence.Result(s): During 2,149,385 person-years of follow-up, 26,208 women reported a history of infertility, and we documented 6,925 incident invasive cancer cases. After adjusting for body mass index and other risk factors, women who reported infertility had a higher risk of developing cancer than gravid women without a history of infertility (HR, 1.07; 95% CI, 1.02-1.13). This association was stronger among obesity-related cancers (HR, 1.13; 95% CI, 1.05-1.22; vs. non-obesity-related cancers, HR, 0.98; 95% CI, 0.91-1.06) and, in particular, obesity-related reproductive cancers (postmenopausal breast, endometrial, and ovarian cancers; HR, 1.17; 95% CI, 1.06-1.29) and was stronger among women who first reported infertility earlier in life (%25 years, HR, 1.19; 95% CI, 1.07-1.33; 26-30 years, HR, 1.11; 95% CI, 0.99-1.25; >30 years, HR, 1.07; 95% CI, 0.94-1.22; P trend < .001).Conclusion(s): A history of infertility may be associated with the risk of developing obesity-related reproductive cancers; further study is needed to elucidate the underlying mechanisms. (Fertil Sterile 2023;120:134-42. & COPY;2023 by American Society for Reproductive Medicine.) El resumen esta disponible en Espanol al final del articulo.

Automated summary

This prospective cohort study examined the association between infertility and the incidence of invasive cancer in women. It found that women who reported infertility had a higher risk of developing cancer, especially obesity-related reproductive cancers. The risk was also higher for women who first reported infertility at a younger age.