Physical activity, hormone replacement therapy and breast cancer risk: A meta-analysis of prospective studies

Pizot, Cécile; Boniol, Mathieu; Mullie, Patrick; Koechlin, Alice; Boniol, M.; Boyle, Peter; Autier, Philippe

doi:10.1016/j.ejca.2015.10.063

Cited by 133 publications

(67 citation statements)

References 79 publications

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“…A meta-analysis of 38 cohort studies reported a relative risk of 0.88 (95% CI: 0.89, 0.90) for breast cancer incidence comparing highest vs. lowest categories of physical activity during adulthood [1]. Evaluating risk factors during childhood and adolescence is of particular interest as early life may be a window of susceptibility due to breast development and hormonal changes [2].…”

Section: Introductionmentioning

confidence: 99%

Childhood and teenage physical activity and breast cancer risk

Niehoff

White

Sandler

2017

Breast Cancer Res Treat

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Purpose Adult physical activity is associated with reduced breast cancer risk, but few studies have evaluated activity before adulthood. Early life may be an important period because of rapid breast development and hormonal changes. This study contributes new information by examining childhood (age 5–12) and teenage (age 13–19) activity separately and overall. Methods The Sister Study is a cohort of 50,884 women aged 35–74. Women reported age 5–19 sports/exercise activities and age 10 and 16 unstructured activities. Both hours and MET-hours of activity were considered in association with breast cancer overall, by ER status, and menopausal status. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards models. Results 2,416 cases were diagnosed during follow-up (mean=6.4 years). Participation in 7+ hours (vs <1 hour) per week of sports/exercise during ages 5–19 was associated with reduced breast cancer risk (HR=0.75; 95% CI: 0.57–0.99). 7+ hours (vs <1 hour) per week of unstructured physical activity at age 16, but not age 10, was inversely associated with breast cancer (HR=0.81; 95% CI: 0.70–0.95). Associations were more pronounced for ER+ tumors, especially for activity during the childhood (age 5–12) period. Due to low correlation between childhood/teenage and adulthood activity in this study (r=0.1), it is unlikely that recent activity explains our results. Conclusions Findings from this large cohort indicate higher levels of physical activity during ages 5–19 are inversely associated with breast cancer risk, supporting early life as a window of susceptibility for breast cancer development.

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Section: Introductionmentioning

confidence: 99%

Childhood and teenage physical activity and breast cancer risk

Niehoff

White

Sandler

2017

Breast Cancer Res Treat

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“…Lastly, this study cannot identify those factors likely to modify the association between physical activity and health outcomes.For instance, a recent study showed that the apparently moderate risk reduction observed for breast cancer could be due to the influence of hormone replacement therapy (HRT). 8 Use of HRT would abolish the protective properties of physical activity, while women never taking HRT could enjoy risk reductions of around 23% thanks to moderate and vigorous physical activity.…”

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confidence: 99%

Meaningless METS: studying the link between physical activity and health

Autier

Pizot

2016

BMJ

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“…First of all, although in vitro, the variant genotype is associated with a substantial decrease in enzymatic activity [11], this functional polymorphism may be an important but not the exclusive influencing factor in etiology and pathogenesis of breast cancer. Special lifestyle and environmental factors, such as tea drinking [61], dietary intake of folate, vitamin B 6 and B 12 [62], physical activities [63], long-term oral contraceptive use [64], and hormone replacement therapy use [65], are possibly confounding factors taking part in the disease etiology. Moreover, differences in patient choosing criteria, ethnicity, sample size, and sources of control could contribute to inconsistency.…”

Section: Discussionmentioning

confidence: 99%

Association between MTHFR gene 1298A>C polymorphism and breast cancer susceptibility: a meta-analysis based on 38 case-control studies with 40,985 subjects

Zhang

2016

World J Surg Onc

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BackgroundStudies investigating the association between the methylenetetrahydrofolate reductase (MTHFR) gene 1298A>C polymorphism and the risk of breast cancer have reported inconsistent results. So, we performed this updated meta-analysis and tried to give a more precise estimation of association between MTHFR gene 1298A>C polymorphism and breast cancer susceptibility.MethodsRelevant studies published before 1 January 2016 were identified by searching PubMed and EMBASE. The strength of relationship between the MTHFR gene 1298A>C polymorphism and breast cancer susceptibility was assessed using odds ratio (OR) and corresponding 95 % confidence interval (95 % CI). The meta-analysis was performed using Stata 11.0 software.ResultsA total number of 38 case-control studies including 18,686 cases and 22,299 controls were identified. No association was found in five genetic models (dominant model: OR = 0.99, 95 % CI 0.99–1.00, P = 0.218; recessive model: OR = 1.00, 95 % CI 0.97–1.02, P = 0.880; homozygote genetic model: OR = 0.99, 95 % CI 0.98–1.01, P = 0.390; heterozygote genetic model: OR = 0.99, 95 % CI 0.97–1.00, P = 0.138; and allele contrast genetic model: OR = 0.99, 95 % CI 0.98–1.01) for MTHFR gene 1298 A>C polymorphism and breast cancer susceptibility. In the subgroup analysis stratified by source of control, decreased risk of breast cancer was found in studies with hospital-based controls in dominant model (OR = 0.98, 95 % CI 0.96–1.00, P = 0.037).ConclusionsOur meta-analysis suggested that there is no significant association between MTHFR gene 1298A>C polymorphism and breast cancer susceptibility for overall population.

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Physical activity, hormone replacement therapy and breast cancer risk: A meta-analysis of prospective studies

Abstract: Increasing physical activity is associated with meaningful reductions in the risk of breast cancer, but in women who ever used HRT, the preventative effect of physical activity seems to be cancelled out.

Cited by 133 publications

References 79 publications

Childhood and teenage physical activity and breast cancer risk

Childhood and teenage physical activity and breast cancer risk

Meaningless METS: studying the link between physical activity and health

Association between MTHFR gene 1298A>C polymorphism and breast cancer susceptibility: a meta-analysis based on 38 case-control studies with 40,985 subjects

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