Lower lifetime occurrence of breast cancer and cancers of the reproductive system among former college athletes

Frisch, Rose E.; Wyshak, Grace; Albright, Nile L.; Albright, Tenley E.; Schiff, Isaac; Witschi, Jelia C.; Marguglio, M

doi:10.1093/ajcn/45.1.328

Cited by 90 publications

(33 citation statements)

References 28 publications

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“…16,18,32,33 Apart from the study type or timing of physical activity, the decrease in risk for postmenopausal breast cancer associated with a higher level of leisure-time physical activity in our study is consistent with the results of several previous studies. 14,16,18,19,[32][33][34][35][36] In the present study, as well as in others, [37][38][39] weight gain and high BMI are important breast cancer risk factors in postmenopausal women and are probably more pronounced among nonusers of hormones than among users of such therapy. 39,40 Aromatization of androstenedione to estrone, the major source of estrogens in postmenopausal women, 41 takes place predominantly in fat tissues.…”

Section: Physical Activitysupporting

confidence: 68%

“…2 Nevertheless, epidemiologic data in studies on physical activity and breast cancer risk remain inconclusive. [3][4][5][6][7][8][9][10][11][12] Although some studies show a clear protection, 5,7,8,[12][13][14][15][16][17] others reveal only a weak, often nonsignificant association 18,19 or no association at all. 10,11,20,21 Many factors could explain these discrepancies.…”

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confidence: 99%

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Physical activity and risk for breast cancer a prospective cohort study among Swedish twins

Moradi

Adami

Ekbom

et al. 2002

Intl Journal of Cancer

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The epidemiologic association between physical activity and breast cancer has been corroborated in many studies. Some inconsistencies remain, possibly due to variation in life periods for exposure assessment, confounding and undetected effect modification. In our cohort study, we address some of these questions by taking into account physical activity in different periods of life and by investigating effect modification by birth cohort and body mass index (BMI). Altogether 9,539 same-sex twin women aged 42-70 years who answered a questionnaire about their work and leisure-time physical exercise from ages 25 to 50 during 1967 and 1970 were included in our cohort. During follow-up, 506 breast cancer cases occurred through 1997. We used multivariate Cox models to estimate relative risk (RR) with 95% confidence interval (CI). We found no associations between physical activity and breast cancer overall. Women born between 1901 and 1917 (aged 51-70 at baseline) who reported regular leisure-time activity had a borderline significant 40% lower risk compared with those who reported no activity (RR 0.6; 95% CI 0.4 -1.0; test for trend, p ‫؍‬ 0.07). This association appeared to be confined to women with a low BMI after the age of 50 and to women with a high BMI during the premenopausal period. We found no evidence that work activity reduces risk for breast cancer. Physical activity might be one of the few realistic approaches toward primary prevention of breast cancer through changes in lifestyle. A protective effect is biologically plausible because physical activity may influence several factors relevant to breast carcinogenesis, such as menstrual characteristics, body size, the immune system 1 and the hormonal system including insulin-like growth factor I (IGF-I) levels. 2 Nevertheless, epidemiologic data in studies on physical activity and breast cancer risk remain inconclusive. [3][4][5][6][7][8][9][10][11][12] Although some studies show a clear protection, 5,7,8,[12][13][14][15][16][17] others reveal only a weak, often nonsignificant association 18,19 or no association at all. 10,11,20,21 Many factors could explain these discrepancies. First of all, obtaining reliable information about physical exercise throughout adult life is a complicated affair. Hence, misclassification of exposure could easily entail underestimation of any true association or cancel it altogether. In addition, several other breast cancer risk factors may modify the effect of physical activity on breast cancer risk, as indicated by recent studies. For example, we observed that physical activity reduced breast cancer risk only among women with a low body mass index (BMI) who were nonusers of postmenopausal hormone therapy. 15 Moreover, such therapy may increase breast cancer risk, chiefly in women with a low BMI. 22 Hence, if women with a low BMI are both more susceptible to exogenous hormones and more protected by physical activity, the protective effect of physical activity on breast cancer risk may be obscured among lean women who use exogenous...

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Section: Physical Activitysupporting

confidence: 68%

mentioning

confidence: 99%

Physical activity and risk for breast cancer a prospective cohort study among Swedish twins

Moradi

Adami

Ekbom

et al. 2002

Intl Journal of Cancer

View full text Add to dashboard Cite

show abstract

“…A lower incidence of breast cancer has been shown in ballet dancers and gymnasts and this has been related to their exercise and delayed onset of menarche (Frisch et al, 1987). In the case of postmenopausal women, obesity is clearly associated with increased breast cancer risk.…”

Section: Physical Exercise Breast Cancer and Insulin Resistancementioning

confidence: 99%

Western nutrition and the insulin resistance syndrome: A link to breast cancer

1999

Eur J Clin Nutr

108

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Objective: The incidence of breast cancer in the Western world runs parallel to that of the major components of the insulin resistance syndrome Ð hyperinsulinaemia, dyslipidaemia, hypertension and atherosclerosis. Evidence is reviewed that the growth of breast cancer is favoured by speci®c dietary fatty acids, visceral fat accumulation and inadequate physical exercise, all of which are thought to interact in favouring the development of the insulin resistance syndrome. Design: Clinical, epidemiological and experimental studies linking breast cancer risk with evidence of insulin resistance and its concomitants, were searched for in the MEDLINE database since 1985. Results: Clinical and epidemiological evidence suggests that both breast cancer and the metabolic disorders comprising the insulin resistance syndrome are polygenic and multifactorial in origin. Experimental evidence suggests that hyperinsulinaemia and its concomitants can increase the promotion of mammary carcinogenesis and the mechanism is likely to involve increased bioactivity of insulin-like growth factor 1 (IGF-1). Case-control and cohort studies have shown that higher serum levels of IGF-1 are associated with increased breast cancer risk. Pharmacological agents which lower IGF-1 concentrations are under clinical trial for breast cancer prevention. Conclusions: Nutritional and lifestyle modi®cations that improve insulin sensitivity may not only decrease a tendency to atherosclerosis but also reduce breast cancer risk in women. In addition to a reduced fat intake, the dietary regimen might involve a reduced n-6/n-3 ratio of polyunsaturated fatty acids and should be associated with avoidance of obesity and regular physical exercise. Interventions to decrease breast cancer risk in ®rst-degree relatives of breast cancer patients need to begin at an early age.

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“…Extreme leanness together with strenuous physical exercise are associated with delayed onset of menarche in ballet dancers and gymnasts, and a decreased breast cancer rate has been shown in athletes. 41 Nevertheless, no association has been shown between body mass in childhood (9 ± 14 y) and subsequent breast cancer risk. 7,8,10,42 Although menarche is likely to be triggered by a threshold level of adiposity, the mechanism is uncertain.…”

Section: Nutrition Obesity and Insulin Resistancementioning

confidence: 99%

Teenage obesity in relation to breast cancer risk

1998

Int J Obes

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While most studies show a higher body mass in Western women to be positively associated with an increased breast cancer risk in postmenopausal women, they show a negative association in the case of premenopausal women. A review of case-control and cohort studies suggest that such protection applies mainly to obesity in teenage girls, whereas obesity appearing after the teenage years is more likely to be associated with a higher risk of postmenopausal breast cancer. The mechanisms are uncertain. There is evidence that obesity and the components of the Western diet can independently provoke hyperinsulinaemic insulin resistance at puberty, and in adolescent girls this has been related to evidence of abnormal ovarian steroidogenesis and anovulation. This may decrease promotion of mammary carcinogenesis. If however, obesity continues after the teenage years, the higher concentration of insulinlike growth factor 1 (IGF1) associated with hyperinsulinaemia can interact with oestrogen receptors in mammary epithelium to lead to increased proliferative activity.This review postulates that the observed protective effect of early obesity against premenopausal breast cancer is likely to be replaced by an increased risk of postmenopausal breast cancer if obesity continues after the teenage years. The manifestation of breast cancer is merely postponed to an older age. Recent prospective and case-control studies suggest that increased bioavailability of IGF1 is a marker of increased breast cancer risk in premenopausal women. Nutritional intake in early life may programme later activity in the growth hormone ± IGF1 axis and in¯uence the progression of transformed cells in mammary tissue. The question remains whether deliberate weight loss can reverse the effects of weight gain.

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Lower lifetime occurrence of breast cancer and cancers of the reproductive system among former college athletes

Cited by 90 publications

References 28 publications

Physical activity and risk for breast cancer a prospective cohort study among Swedish twins

Physical activity and risk for breast cancer a prospective cohort study among Swedish twins

Western nutrition and the insulin resistance syndrome: A link to breast cancer

Teenage obesity in relation to breast cancer risk

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