A case-control study was conducted in Los Angeles County, California, of 127 endometrial cancer cases aged 45 years or less at diagnosis, to investigate the role of fertility, obesity and exogenous oestrogens in the development of the disease in young women. Use of sequential oral contraceptive (SOCs) or oestrogen replacement therapy (ERT) for greater than or equal to 2 years was strongly associated with increased risk of endometrial cancer. After excluding these cases, since the SOC or ERT use was probably the cause of their disease, we were left with 110 case-control pairs for further study. Among these remaining case-control pairs increasing parity was strongly associated with decreased risk (relative risk of 0.12 for women of parity 3 compared to nulliparous women, P less than 0.001). Current weight was associated with increased risk (relative risk of 17.7 for women weighing greater than or equal to 190 lbs compared to women weighing less than 130 lbs, P less than 0.001). Combination oral contraceptive (COC) use was associated with a decreased risk, which decreased with duration of COC use (relative risk of approximately 0.28 at 5 years of use, P less than 0.001), but the estimate of the protective effect was reduced and became statistically non-significant when allowance was made for weight and parity. The protective effect of COC use was only clearly evident in women who had less than 3 live-births and weighed less than 170 lbs. These results provide further support for the "unopposed" oestrogen hypothesis of the aetiology of endometrial cancer.
PIP: A case-control study was conducted in Los Angeles County, California, of 127 endometrial cancer cases aged 45 years or less, in order to investigate the role of fertility, obesity, and exogenous estrogens in the development of the disease in young women. Use of sequential oral contraceptives (OCs) or estrogen replacement therapy (ERT) for or= 2 years was strongly associated with increased risk of endometrial cancer. After excluding these cases since the OCs or ERT use were probably responsible for their disease, we were left with 110 case control pairs for further study. Among these remaining case control pairs, increasing parity was strongly associated with decreased risk (relative risk of 0.12 for women of parity 3 compared to nulliparous women, P0.001). Current weight was associated with increased risk (relative risk of 17.7 for women weighing or= 190 pounds compared to weighing 130 pounds, P0.001). Combination OC use was associated with a decreased risk, which decreased with duration of combination OC use (relative risk of approximately 0.28 at 5 years of use, P0.001), but the estimate of the protective effect was reduced and became statistically nonsignificant when allowance was made for weight and parity. The protective effect of combination OC use was only clearly evident in women who had less than 3 live births and weighed less than 170 pounds. These results provide further support for the unopposed estrogen hypothesis of the etiology of endometrial cancer.