Objectives. We prospectively examined nonrecreational physical activity and sedentary behavior in relation to breast cancer risk among 97039 postmenopausal women in the National Institutes of Health-AARP Diet and Health Study.

Methods. We identified 2866 invasive and 570 in situ breast cancer cases recorded between 1996 and 2003 and used Cox proportional hazards regression to estimate multivariate relative risks (RRs) and 95% confidence intervals (CIs).

Results. Routine activity during the day at work or at home that included heavy lifting or carrying versus mostly sitting was associated with reduced risk of invasive breast cancer (RR=0.62; 95% CI=0.42, 0.91; Ptrend=.024).

Conclusions. Routine activity during the day at work or home may be related to reduced invasive breast cancer risk. Domains outside of recreation time may be attractive targets for increasing physical activity and reducing sedentary behavior among postmenopausal women. (Am J Public Health. Published online ahead of print September 23, 2010: e1-e8. doi:10.2105/AJPH.2009.180828). Note: RR=.62 = 38% relative risk reduction

BACKGROUND. Low fat, high fiber dietary interventions that decrease blood estrogen levels may reduce breast cancer risk. Asian women consuming their traditional low fat, high fiber diets have lower blood estrogen levels before and after menopause and lower rates of breast cancer compared with Western women. The current controlled feeding study of premenopausal women was designed to determine the effects of a very low fat (10% of calories) and high fiber (35-45 g/day) diet on blood estrogen levels and menstrual function.

METHOD. Twelve healthy premenopausal women with regular ovulatory cycles were followed for 3 months. Subjects consumed a diet providing 30% of their energy from fat and 15-25 g of dietary fiber per day for 1 month, and they consumed a very low fat, high fiber and libitum diet providing 10% of their energy from fat and 25-35 g of dietary fiber per day for 2 months.

RESULTS. At the end of the second month of the very low fat, high fiber diet, there was a significant reduction in serum estrone and estradiol levels during the early follicular and late luteal phases. There were no significant changes observed in serum estrone sulfate, sex hormone binding globulin, or progesterone. Despite a significant decrease in serum estradiol and estrone levels after 2 months of a very low fat, high fiber diet, there was no interference with ovulation or the magnitude of the mid-cycle leuteinizing hormone surge. Small changes in menstrual cycle length of up to 3 days were not ruled out due to the small sample size of the study.

CONCLUSIONS. A very low fat, high fiber diet in healthy premenopausal women can reduce estradiol and estrone levels without affecting ovulation, thereby providing a rationale for the prevention of breast cancer through a very low fat, high fiber diet.

BACKGROUND:Ecological studies have suggested that vitamin D production through ultraviolet (UV) solar irradiance could reduce breast cancer (BC) risk. Although studies restricted to dietary vitamin D intake have provided inconsistent results, little is known about the relationship between pre- and postmenopausal BC and combined intakes from diet, supplements, and sun exposure.

METHODS:Cox proportional hazards regression models evaluated the association between vitamin D intakes, mean daily ultraviolet radiation dose (UVRd) at the place of residence and risk of BC among 67,721 women of the French E3N cohort. All analyses were stratified on menopausal status taking into account important confounders including calcium consumption.

RESULTS:During 10 years of follow-up, a total of 2,871 BC cases were diagnosed. Dietary and supplemental vitamin D intakes were not associated with BC risk; however, in regions with the highest UVRd, postmenopausal women with high dietary or supplemental vitamin D intake had a significantly lower BC risk as compared with women with the lowest vitamin D intake (HR = 0.68, 95% CI: 0.54-0.85, and HR = 0.57, 95% CI: 0.36-0.90, respectively).

CONCLUSION:Our results suggest that a threshold of vitamin D exposure from both sun and diet is required to prevent BC and this threshold is particularly difficult to reach in postmenopausal women at northern latitudes where quality of sunlight is too poor for adequate vitamin D production.

IMPACT:Prospective studies should further investigate associations between BC risk, vitamin D status and sunlight exposure.

OBJECTIVE: Physical activity may decrease breast cancer risk. However, it is unclear what intensity of exercise and during which life periods this effect on decreasing risk is efficiently expressed, and whether the associations differ by the estrogen-/progesterone- receptor (ER/PR) status of tumors. We investigated associations between age- and intensity-specific leisure-time physical activity and ER/PR-defined breast cancer risk.

METHODS: We conducted a hospital-based case-control study in Nagano, Japan. Subjects were 405 cases newly diagnosed (>99% known ER/PR) from 2001 to 2005, who were age-/area-matched with 405 controls. Activity was assessed with a self-reported questionnaire which considered intensity level (moderate and/or strenuous) at different ages (at 12 and 20 years, and in the previous 5 years). Odds ratios (ORs) and 95% confidence intervals were calculated using logistic regression.

RESULTS: Strenuous but not moderate physical activity at age 12 was inversely associated with pre- and postmenopausal breast cancer risk across ER/PR subtypes [overall OR(>/=5 days/week vs. none) = 0.24 (0.14-0.43)]. Moderate physical activity in the previous 5 years was significantly associated with a decrease in risk for postmenopausal ER + PR + tumors only [OR(>/=1 day/week vs. none) = 0.35 (0.18-0.67)].

CONCLUSION: Strenuous activity in teens and moderate activity after menopause may contribute to a reduction in breast cancer risk.

To investigate the role of lifelong vegetarianism on the aetiology of female breast cancer, we conducted a population-based case-control study among South Asian migrant women from the Indian subcontinent resident in England. A total of 240 South Asian breast cancer cases were identified from 2 cancer registries during 1995-1999. For each case, 2 age-matched South Asian controls were randomly selected from the age-sex register of the case practice. Lifelong vegetarians had a slight reduction, although not statistically significant, in the odds of breast cancer relative to lifelong meat-eaters, which persisted after adjustment for socio-demographic and reproductive variables [odds ratio (OR)=0.77; 95% confidence interval (CI)=0.50-1.18]. Analysis by food group revealed no linear trend in the odds of breast cancer with increasing consumption of meat (p=0.10) but the odds were higher for women in the top 75%. In contrast, there were strong inverse trends in the odds of breast cancer with increasing intake of vegetables (p=0.005), pulses (p=0.007) and fibre [non-starch polysaccharides, NSP (p=0.02)], with women in the highest 25% of intake of these foods having about 50% of the odds of those in the lowest ones. Adjustment for intake of vegetables and pulses reverted the odds of breast cancer in lifelong vegetarians relative to lifelong meat-eaters (OR=1.04; 95% CI=0.65-1.68) and attenuated the quartile-specific estimates for meat intake, whereas the inverse trends in the odds of breast cancer with intake of vegetables and pulses remained after adjustment for type of diet or meat intake. These findings suggest that lifelong vegetarianism may be associated with a reduction in the risk of breast cancer through its association with a higher intake of vegetables and pulses. Although it is not possible to exclude the possibility that lifelong meat abstention may also play a role, the findings provide evidence that a diet rich in vegetables and pulses, such as those typically found in South Asian diets, may be protective against this cancer.

Telomeres play a critical role in maintaining the integrity and stability of the genome, and are susceptible to oxidative damage after telomere shortening to a critical length. In the present study, we explored the role of white blood cell DNA telomere length on breast cancer risk, and examined whether urinary 15-F(2)-isoprostanes (15-F(2t)-IsoP) and 8-oxo-7,8-dihydrodeoxyguanosine (8-oxodG) or dietary antioxidant intake modified the relationship between telomere length and breast cancer risk. A population-based case-control study-the Long Island Breast Cancer Study Project-was conducted among 1,067 cases and 1,110 controls. Telomere length was assessed by quantitative PCR. Overall, the mean levels of telomere length (T/S ratio), 15-F(2t)-IsoP and 8-oxodG were not significantly different between cases and controls. Among premenopausal women only, carrying shorter telomeres (Q3 and Q4), as compared with the longest (Q1), was associated with significantly increased breast cancer risk. Age-adjusted OR and 95% CI were 1.71 (1.10-2.67) and 1.61 (1.05-2.45). The 5-F(2t)-IsoP and 8-oxodG biomarkers did not modify the telomere-breast cancer association. A moderate increase in breast cancer risk was observed among women with the shortest telomeres (Q4) and lower dietary and supplemental intake of beta-carotene, vitamin C or E intake [OR (95% CI) = 1.48 (1.08-2.03), 1.39 (1.01-1.92) and 1.57 (1.14-2.18), respectively], although the trend test exhibited statistical significance only within the lower vitamin E intake subgroup (p(trend) = 0.01). These results provided the strongest evidence to date that breast cancer risk may be affected by telomere length among premenopausal women or women with low dietary intake of antioxidants or antioxidant supplements.