Nulliparity Does Not Modify Endometrial Cancer Risk
Nulliparity Does Not Modify Endometrial Cancer Risk
Schonfeld SJ, Hartge P, Pfeiffer, RM, et al. An aggregated analysis of hormonal factors and endometrial cancer risk by parity. Cancer 2012 Dec 20. doi: 10.1002/cncr.27909. [Epub ahead of print]
It is clear that nulliparity is associated with an increased risk of endometrial cancer. It is less clear whether nulliparity modifies the association between other established hormone-related risk factors. Although the proportion of nulliparous women has increased since the mid-1970s, studies to date have been too small to test the hypothesis that endometrial cancer risk factors are more common in nulliparous women than parous women.
Schonfeld et al conducted a large, pooled analysis of data aggregated on 26,936 postmenopausal, Caucasian, nulliparous women (360 endometrial cancers) and 146,583 postmenopausal, Caucasian, parous women (1,378 endometrial cancers) from four US prospective studies (1979-2006). HRs and 95% CIs were estimated in stratified analyses. Endometrial cancer was higher among nulliparous women, as expected (nulliparous vs parous: HR, 1.42; 95% CI, 1.26-1.60). Stratified associations between endometrial cancer and hormone-related risk factors did not differ between nulliparous versus parous women: For both groups, oral contraceptives and earlier menopause were associated with reduced risk. The highest HRs were for obesity; a BMI of 30 kg/m (vs <25 kg/m) increased the risk of endometrial cancer threefold among nulliparous women (HR, 3.04; 95% CI, 2.34-3.94) and parous women (HR, 2.88; 95% CI, 2.52-3.29).
The authors concluded that nulliparity does not modify risks of endometrial cancer associated with established hormone-related risk factors.
Summary
Schonfeld SJ, Hartge P, Pfeiffer, RM, et al. An aggregated analysis of hormonal factors and endometrial cancer risk by parity. Cancer 2012 Dec 20. doi: 10.1002/cncr.27909. [Epub ahead of print]
It is clear that nulliparity is associated with an increased risk of endometrial cancer. It is less clear whether nulliparity modifies the association between other established hormone-related risk factors. Although the proportion of nulliparous women has increased since the mid-1970s, studies to date have been too small to test the hypothesis that endometrial cancer risk factors are more common in nulliparous women than parous women.
Schonfeld et al conducted a large, pooled analysis of data aggregated on 26,936 postmenopausal, Caucasian, nulliparous women (360 endometrial cancers) and 146,583 postmenopausal, Caucasian, parous women (1,378 endometrial cancers) from four US prospective studies (1979-2006). HRs and 95% CIs were estimated in stratified analyses. Endometrial cancer was higher among nulliparous women, as expected (nulliparous vs parous: HR, 1.42; 95% CI, 1.26-1.60). Stratified associations between endometrial cancer and hormone-related risk factors did not differ between nulliparous versus parous women: For both groups, oral contraceptives and earlier menopause were associated with reduced risk. The highest HRs were for obesity; a BMI of 30 kg/m (vs <25 kg/m) increased the risk of endometrial cancer threefold among nulliparous women (HR, 3.04; 95% CI, 2.34-3.94) and parous women (HR, 2.88; 95% CI, 2.52-3.29).
The authors concluded that nulliparity does not modify risks of endometrial cancer associated with established hormone-related risk factors.