Endometrial Cancer and Age at Last Delivery: Evidence for an Association

Abstract

Because the role hormonal and reproductive factors play in the etiology of endometrial cancer is incompletely understood, the authors evaluated the risk of this cancer in relation to age at last delivery. The data were obtained in a hospital-based case-control study of 483 women with endometrial cancer (cases) and 693 women with other conditions (controls) conducted in a number of hospitals in the United States and Canada from 1978 to 1985. There was an inverse association between age at last delivery and endometrial cancer risk: Compared with women who last gave birth before age 25 years, the rate ratio was 0.9 (95% confidence interval (CI) 0.5-1.6) for last delivery at ages 25-29 years, 0.6 (95% CI 0.3-1.0) for last delivery at ages 30-34 years, 0.5 (95% CI 0.3-1.0) for last delivery at ages 35-39 years, and 0.4 (95% CI 0.1-0.9) for last delivery at age 40 years or older. The trend of decreasing rate ratio with increasing age at last delivery was statistically significant (p = 0.02). The association was apparent regardless of parity or menopausal status. There was no evidence for an association between age at first pregnancy and risk. These data suggest that women who bear children late in reproductive life may be at lower risk for endometrial cancer than those who complete their families early.

Reproductive risk factors for endometrial cancer among Polish women

“…This includes oral contraceptives, a recognised protective factor for endometrial cancer, and an exposure that would undoubtedly be more prevalent among subjects with late ages at first birth. This was not an important confounder in our study, given low rates of usage among Polish women, but other studies that have adjusted for oral contraceptives have shown a persistent effect of ages at last birth (Lesko et al, 1991;Parazzini et al, 1998). It seems more likely that differing analytic techniques may explain study discrepancies, as an analysis that appropriately accounted for correlated variables also did not confirm an effect of late ages at a last birth .…”

“…We used a modelling approach ) that enabled combining data from parous and nulliparous women to separately evaluate effects of different parameters. We were particularly interested in following up the observations of an inverse relationship of endometrial cancer risk with ages at (Kvale et al, 1988;Lesko et al, 1991;Parazzini et al, 1991Parazzini et al, , 1998Lambe et al, 1999) and intervals since (Albrektsen et al, 1995;Parazzini et al, 1998) a last birth. Our results, like others (Shu et al, 1991;McPherson et al, 1996;Albrektsen et al, 1999), provide little support for these relationships.…”

“…This factor has not generally been regarded as a predictor of endometrial cancer risk (Pettersson et al, 1986;Lesko et al, 1991;Brinton et al, 1992;Parazzini et al, 1998;Xu et al, 2004), despite a number of studies that have demonstrated relatively strong associations (Kvale et al, 1988;Parslov et al, 2000;Hinkula et al, 2002;Wernli et al, 2006). Although it is widely accepted that multiparity may reduce endometrial cancer risk through changes in hormonal profiles, including lowered estradiol and increased sex hormone binding globulin levels (Chubak et al, 2004), underlying mechanisms for reduced risks associated with delayed ages at a first birth are less clear.…”

“…Inverse associations with later ages at a first birth have been demonstrated in some studies (Kvale et al, 1988;Albrektsen et al, 1995;Parslov et al, 2000;Wernli et al, 2006), although not in all of them (Lesko et al, 1991;Parazzini et al, 1991Parazzini et al, , 1998Shu et al, 1991;Brinton et al, 1992;McPherson et al, 1996;Lambe et al, 1999). More recently, studies have suggested that risk may decrease with later ages at a last birth (Kvale et al, 1988(Kvale et al, , 1991Lesko et al, 1991;Parazzini et al, 1991Parazzini et al, , 1998Lambe et al, 1999). This may reflect the fact that late ages at a last birth tend to be associated with shorter intervals since last births (Albrektsen et al, 1995;Parazzini et al, 1998), prompting the suggestion that premalignant or initiated cells may be mechanically cleared during the birth process (Kvale et al, 1991;Lambe et al, 1999).…”

Geographic and temporal variations in cancer of the corpus uteri: Incidence and mortality in pre- and postmenopausal women in Europe

“…Several studies have found an inverse association between older age at last birth and corpus uteri cancer risk, [39][40][41] hypothesised to be due to mechanical shedding of cells that have undergone malignant transformation in women when they give birth. 42 Further, it appears that the association is stronger in women aged below 50 years than in women over 50.…”