Physical Activity and Breast Cancer Risk Among Women in the Southwestern United States

Abstract

Physical activity may influence breast cancer risk through multiple mechanisms and at different periods in life. In this study we evaluate breast cancer risk associated with total and vigorous physical activity at ages 15, 30, and 50 years and the referent year prior to diagnosis/selection. Participants were non-Hispanic white (NHW) (1527 cases and 1601 control subjects) and Hispanic/American Indian (HAI) (798 cases and 924 controls) women. Both total and vigorous activity reduced risk of breast cancer in a dose-response manner. Among premenopausal women, only high total metabolic equivalent of the task (MET) hours of activity during the referent year was associated with reduced breast cancer risk in NHW women (odds ratio [OR] 0.62; 95% confidence interval [CI] 0.43, 0.91). Among postmenopausal women, physical activity had the greatest influence among women not recently exposed to hormones. Among these women, high total lifetime activity reduced risk of breast cancer for both NHW (OR 0.60; 95% CI 0.36, 1.02; p trend 0.01) and HAI women (OR 0.52; 95% CI 0.23, 1.16; p trend 0.07). Additionally, high total MET hours of activity at age 30 years (OR 0.56; 95% CI 0.37, 0.85) and at age 15 years (OR 0.57; 95% CI 0.38, 0.88) reduced breast cancer risk among postmenopausal NHW women not recently exposed to hormones. Among HAI women, more recent activity performed during the referent year and at age 50 appeared to have the greatest influence on breast cancer risk. Among postmenopausal NHW women. there was a significant interaction between physical activity and hormone replacement therapy (p value, 0.01), while among postmenopausal HAI women, physical activity interacted with body mass index (p value, 0.04). These data suggest that physical activity is important in reducing risk of breast cancer in both NHW and HAI women.

Recent Recreational Physical Activity and Breast Cancer Risk in Postmenopausal Women in the E3N Cohort

“…HRs for hormone receptor-defined invasive breast cancer according to level of recreational physical activity within the previous 4 years Contrary to most studies, which have not found that the relation between physical activity and breast cancer risk was modified by weight changes before inclusion (9,11,13,21,30), three articles report that the risk decrease associated with baseline physical activity is restricted to postmenopausal women with limited weight gain between youth and baseline (22,31,32). However, a weight gain before baseline may be associated with a decrease in physical activity after baseline (33).…”

“…However, the leanness of E3N women did not allow to explore the effect in higher categories of BMI or waist circumference. Similarly, most studies did not observe modifications in this relation according to hormone receptor status during postmenopause (6,10,13,(22)(23)(24)(25)(26). The risk reduction was limited to ER À (27) and PR þ (28) subtypes in two prospective studies and apparent only for postmenopausal ER þ /PR À (29) and ER þ /PR þ (25) cancers in two other studies (no tests for homogeneity).…”

Breast cancer incidence among American Indian and Alaska Native women: US, 1999-2004

“…The Four-Corners Breast and Endometrial Cancer Study (Arizona, New Mexico, Colorado, and Utah-all in the Southwest IHS region), for example, was designed to examine genetic admixture in relation to gene markers and environmental factors among American Indian, Hispanic, and NHW women. 30,31 Studies of breast cancer risk factors and genetic markers also are needed among AI/AN populations in other regions. In Alaska, for example, widespread exposure to organochlorines has been documented, buts its association with breast cancer is uncertain.…”

Posibles mecanismos de acción biológica de la actividad física en el cáncer de mama

“…Se ha demostrado que elevados niveles de actividad física están asociados a niveles inferiores de marcadores de inflamación, el estrógeno ha mostrado ser proinflamatorio, y otros estrógenos como el 17 betaestradiol poseen una función inhibidora de la expresión del gen inflamatorio, que es regulado por el factor nuclear kB (McTiernan et al, 2003;McTiernan, Ulrich, Slate y Potter, 1998;Slattery et al, 2007).…”