We conducted a meta-analysis to summarize the evidence from prospective studies regarding the association between physical activity and breast cancer risk. A comprehensive search was conducted to identify eligible studies. The fixed or random effect model was used based on heterogeneity test. The dose-response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression. Overall, 31 studies with 63,786 cases were included, and the combined relative risk (RR) with 95 % CI of breast cancer was 0.88 (0.85-0.91). In subgroup analysis by activity type, data from 27 studies including 37,568 cases for non-occupational activity (including recreational activity and household activity) and seven studies including 28,268 cases for occupational activity were used, and the RR (95 % CI) of breast cancer was 0.87 (0.83-0.91) and 0.90 (0.83-0.97), respectively. The inverse association was consistent among all subgroups analyses. Stronger association was found for subjects with BMI <25 kg/m(2) [0.72 (0.65-0.81)], premenopausal women [0.77 (0.72-0.84)], and estrogen and progesterone receptor-negative breast cancer [0.80 (0.73-0.87)]. Dose-response analysis suggested that the risk of breast cancer decreased by 2 % (P < 0.00) for every 25 metabolic equivalent (MET)-h/week increment in non-occupational physical activity, 3 % (P < 0.00) for every 10 MET-h/week (roughly equivalent to 4 h/week of walking in 2 miles/h or 1 h/week of running in 6 miles/h) increment in recreational activity, and 5 % (P < 0.00) for every 2 h/week increment in moderate plus vigorous recreational activity, respectively. Physical activity could significantly reduce the risk of breast cancer.
The VEGF-460/-1154/-2578 TGC, CAA, TAA and TAC haplotypes were associated with endometriosis. The -1154A and -2578A alleles may be protective against the development of endometriosis in North Chinese women.
Background:Epidemiological studies evaluating the association of vitamin B6, vitamin B12 and methionine with breast cancer risk have produced inconsistent results.Methods:Pertinent studies were identified by a search in PubMed and Web of Knowledge. Random-effect model was used. Dose–response relationship was assessed by restricted cubic spline.Results:The combined relative risk (95% confidence interval) of breast cancer for the highest vs lowest category of serum pyridoxal 5′-phosphate (PLP, active form of vitamin B6) levels and dietary methionine intake was 0.80 (0.66–0.98, P=0.03) and 0.94 (0.89–0.99, P=0.03), respectively, and the associations of breast cancer with higher serum PLP levels and dietary methionine intake were significant among post-menopausal women, but not among pre-menopausal women. The inverse association between breast cancer risk and dietary vitamin B6 intake, serum vitamin B12 levels and dietary vitamin B12 intake was not significant overall. Linear dose–response relationship was found, and the risk of breast cancer decreased by 23% (P<0.00) for every 100 pmol ml−1 increment in PLP levels and 4% (P=0.05) for every 1 g per day increment in dietary methionine intake, respectively.Conclusion:Serum PLP levels and methionine intake might be inversely associated with breast cancer risk, especially among postmenopausal women, which need to be confirmed.
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