Prospective study of physical activity in different periods of life and the risk of ovarian cancer

Abstract

Only few studies have assessed the role of physical activity in the etiology of ovarian cancer, and the results have been inconclusive. We studied associations between physical activity and risk of ovarian cancer in 96,541 women aged 30-49 at enrollment in a prospective study in Norway and Sweden. Participants reported physical activity level at ages 14, 30 and at enrollment, and participation in competitive sports. Complete follow-up through 2001/ 2002 was achieved by linkage to national registries. The relation between physical activity and ovarian cancer incidence was assessed using multivariate Cox proportional hazard models. During an average 11.1 years of follow-up, there were 264 ovarian cancer cases (including 81 borderline tumors) diagnosed at a mean age of 49 years. Highly physically active women at cohort enrollment had a similar risk of ovarian cancer as women reporting no activity (multivariate relative risk RR 5 1.08, 95% CI 0.53-2.18). Physical activity at age 30 or at age 14 did not either afford any protection from ovarian cancer, nor did a consistently high level of activity from younger ages until enrollment. Results were similar for invasive and borderline tumors, and for different subgroups of women classified according to other known risk factors for ovarian cancer. In our study of primarily premenopausal women, physical activity at different ages did neither reduce nor increase risk of ovarian cancer. In the context of the inconsistent scientific literature, our findings probably reflect that physical activity is not causally related with ovarian cancer. ' 2006 Wiley-Liss, Inc.Key words: physical activity; ovarian cancer cohort study; epidemiology Ovarian cancer is a common neoplasm, ranking seventh for incidence and sixth for mortality in Western countries. 1 Because ovarian cancer is often diagnosed in late stages when cure is no longer possible, it is the leading cause of mortality among gynecological malignancies. 2 No screening method has yet been proven effective; therefore, identifying modifiable risk factors is one strategy to reduce morbidity from this high lethal malignancy.Ovarian cancer is at least partially a hormone-related disease, occurring less frequently in women with longer periods of anovulation due to increasing number of pregnancies or prolonged use of hormonal contraceptives. 3 Increasing circulating levels of estrogens in both pre-and postmenopausal women have been suggested to increase ovarian cancer risk, although the literature is sparse. Moderate levels of physical activity contribute to weight control, and appear to improve immune function. It also possibly decreases urinary estriol and progesterone levels, and increases catecholo-methyltransferase (COMT) activity, which is associated with estrogen metabolism. Vigorous physical activity in premenopausal women can lead to anovulation, luteal-phase insufficienty and amenorrhoea or irregular menstrual cycles, and lower endogenous estrogen levels, urinary LH levels, and impair immune function. 4,5 The hormonal and ...

Body fatness and physical activity at young ages and the risk of breast cancer in premenopausal women

“…We did not find a relationship between any level of BMI at age 20 years and risk, but few women reported having been obese or even overweight at that age. The modest evidence of an inverse association between body fatness at age 10 years and risk of breast cancer among premenopausal women in our data is consistent with other reports (Berkey et al, 1999;Swerdlow et al, 2002;Okasha et al, 2003;Ahlgren et al, 2004;De Stavola et al, 2004;Weiderpass et al, 2004), as is the suggested protective effect of obesity at diagnosis (IARC, 2002). Although body fatness in childhood and early adulthood has been proposed to influence breast carcinogenesis via anovulatory-related progesterone deficiency, decelerated adolescent growth and oestrogen-induced breast epithelial differentiation (Berkey et al, 1999;Cabanes et al, 2004;Magnusson and Roddam, 2005), there is no direct evidence to support these mechanisms.…”

Adult height, age at attained height, and incidence of breast cancer in premenopausal women

“…1,2,29 However, other recent, large prospective studies have shown significant positive associations between height and breast cancer risk in younger women. 8,32 In the present study, women in the tallest height category ( 1.75 m) had more than 50% greater risk of premenopausal breast cancer compared to the shortest women, and each 5-cm increase in adult height was associated with approximately 11% increased risk, the same as that observed for each 5-cm increase in height at age 14 in a large record linkage study from Denmark. 8 In addition to childhood energy intake, adult height may reflect cumulative exposure to growth hormone and IGF-I or number of ductal stem cells in the mammary gland, which also have been proposed as potential biologic mechanisms.…”

Cigarette smoking and risk of borderline and invasive epithelial ovarian cancer

“…The hazard ratio (HR) for each of these factors was estimated in both univariate and multivariate analyses. Factors changing the HR 5% or those previously shown to be related to risk of EOC in this cohort, 21,22 were included in the final multivariate models [age at enrolment (years, continuous), nulliparous (yes/no), duration of hormonal contraceptive use (years) and menopausal status at enrolment (pre/post)]. Women (N 5 1,922) with missing values for any of the co-variates were excluded from the multivariate models.…”