Infertility implicated in obesity-related reproductive cancers
Women with a history of infertility are more likely to develop reproductive cancers that are related to obesity, as reported in a study.
The prospective cohort study included 103,080 women (age 25–42 years) who participated in the Nurses’ Health Study II and were cancer-free at baseline (1989). All participants completed baseline and biennial follow-up questionnaires that provided data on infertility status (failure to conceive after one year of trying) and causes of infertility.
Cancer diagnoses were identified via a medical record review. Cancers were categorized as obesity-related (eg, colorectal, gallbladder, kidney, multiple myeloma, thyroid, pancreatic, oesophageal, gastric, liver, endometrial, ovarian, and postmenopausal breast) or nonobesity-related (all other cancers).
A total of 26,208 women reported a history of infertility, and 6,925 incident invasive cancer cases were documented over 2,149,385 person-years of follow-up.
Multivariable Cox proportional hazards models showed that women who reported infertility had a 7-percent higher risk of cancer compared with those who had no history of infertility (hazard ratio [HR], 1.07, 95 percent confidence interval [CI], 1.02–1.13).
Of note, the association between infertility and cancer was pronounced for obesity-related cancers (HR, 1.13, 95 percent CI, 1.05–1.22) but not for nonobesity-related cancers (HR, 0.98, 95 percent CI, 0.91–1.06). This was especially true for obesity-related reproductive cancers such as postmenopausal breast, endometrial, and ovarian cancers (HR, 1.17, 95 percent CI, 1.06–1.29).
The risk of obesity-related reproductive cancers was elevated among women who reported infertility earlier in life (≤25 years: HR, 1.19, 95 percent CI, 1.07–1.33; 26–30 years: HR, 1.11, 95 percent CI, 0.99–1.25; >30 years: HR, 1.07, 95 percent CI, 0.94–1.22; p<0.001 for trend).
More studies are needed to shed light on the mechanisms underlying the association between infertility and obesity-related reproductive cancers.