Aside from hysterectomy, no consensus suggestion exists for lowering the risk of endometrial cancer in women with a mismatch repair gene mutation (Lynch syndrome). For this study, the researchers wanted to look at the relationship between hormonal variables and the risk of endometrial cancer in those who have Lynch syndrome.

The Colon Cancer Family Registry was used to identify 1128 women who had a mismatch repair gene mutation. A weighted cohort technique was used to examine data. Participants were drawn from facilities in the United States, Australia, Canada, and New Zealand between 1997 and 2012. Age at menarche, first and last live birth, and menopause; the number of live births; use of hormonal contraception; and use of postmenopausal hormones. 


About 133 women were diagnosed with endometrial cancer (incidence rate per 100 person-years, 0.29; 95% CI, 0.24 to 0.34). Endometrial cancer was diagnosed in 11% (n = 70) of women over the age of 13 years, compared to 12.6% (n = 57) of women under the age of 13 years (incidence rate per 100 person-years, 0.27 vs 0.31; rate difference, -0.04 [95% CI, 0.15 to 0.05]; hazard ratio per year, 0.85 [95% CI, 0.73 to 0.99]; P=.04). Endometrial cancer was identified in 10.8% (n = 88) of parous women vs 14.4% (n = 40) of nulliparous women (incidence rate per 100 person-years, 0.25 vs 0.43; rate difference, -0.18 [95% CI, -0.32 to -0.04]; hazard ratio, 0.21 [95% CI, 0.10 to 0.42]; P<.001). Endometrial cancer was diagnosed in 8.7% (n = 70) of women who used hormonal contraceptives for more than or equal to a year, compared to 19.2% (n = 57) of women who used contraceptives for less than a year (incidence rate per 100 person-years, 0.22 vs 0.45; rate difference, -0.23 [95% CI, -0.36 to -0.11]; hazard ratio, 0.39 [95% CI, 0.23 to 0.64 Endometrial cancer did not have a statistically significant relationship with age at first and last live birth, age at menopause, or usage of postmenopausal hormones.