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Abstract

To assess more precisely the relative risks associated with established risk factors for breast cancer, and whether the association between dietary fat and breast cancer risk varies according to levels of these risk factors, we pooled primary data from six prospective studies in North America and Western Europe in which individual estimates of dietary fat intake had been obtained by validated food-frequency questionnaires. Based on information from 322,647 women among whom 4,827 cases occurred during follow-up: the multivariate-adjusted risk of late menarche (age 15 years or more compared with under 12) was 0.72 (95 percent confidence interval [CI] = 0.62-0.82); of being postmenopausal was 0.82 (CI = 0.69-0.97); of high parity (three or more births compared with none) was 0.72 (CI = 0.61-0.86); of late age at first birth (over 30 years of age compared with 20 or under) was 1.46 (CI = 1.22-1.75); of benign breast disease was 1.53 (CI = 1.41-1.65); of maternal history of breast cancer was 1.38 (CI = 1.14-1.67); and history of a sister with breast cancer was 1.47 (CI = 1.27-1.70). Greater duration of schooling (more than high-school graduation compared with less than high-school graduation) was associated significantly with higher risk in age-adjusted analyses, but was attenuated after controlling for other risk factors. Total fat intake (adjusted for energy consumption) was not associated significantly with breast cancer risk in any strata of these non-dietary risk factors. We observed a marginally significant interaction between total fat intake and risk of breast cancer according to history of benign breast disease; with fat intake being associated nonsignificantly positively with risk among women with a previous history of benign breast disease; no other significant interactions were observed. Risks for reproductive factors were similar to those observed in case-control studies; relative risks for family history of breast cancer were lower. We found no clear evidence in any subgroups of a major relation between total energy-adjusted fat intake and breast cancer risk.

Risk Factors for Breast Cancer of Different Age Groups: Moroccan Data?

“…These findings are in line with other studies [5] [6]. Breast cancer shows a strong linked to the early age of menarche and additional years for age at menarche decreased by 5% risk of developing breast cancer [7]. The most convincing explanation for the latter remains the hormonal impregnation that exists during the period of activity of the ovaries [8].…”

Breast cancer epidemiology according to recognized breast cancer risk factors in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial Cohort

“…: 5% decrease in risk per 1-year delay after age 12) and menopause (e.g. : 3% increase in risk per 1-year delay age at menopause)[8,9,18]. In contrast, we observed a fairly uniform decreased risk with older ages at menarche and a non-significant increased risk only in the oldest age-at-menopause group.…”

Hair product use, age at menarche and mammographic breast density in multiethnic urban women

“…Clinical, epidemiological, and laboratory studies have suggested EDCs are associated with earlier pubertal events [ 6 ] and timing of pubertal maturation is associated with breast cancer risk [ 7 ]. For every 1-year delay in menarche, the risk of breast cancer decreases by around 5% [ 8 , 9 ]. Further, certain EDCs are important breast carcinogens that may impact breast tissue remodeling, which in turn may affect mammographic breast density [ 10 ], a measure of the amount of fibroglandular breast tissue and one of the strongest risk factors for breast cancer [ 11 – 13 ].…”