title: [Leanness, obesity, and breast cancer risk-different impact of body weight on breast cancer risk according to women's life stages].
abstract: Numerous epidemiological studies, although not all, in Western countries have reported a possible differential impact of BMI on breast cancer risk in women of various lifestages. Among premenopausal women, a number of epidemiological studies in Western populations suggested a weak inverse association between BMI and breast cancer risk. Conversely, there exists substantial evidence for a statistically significant positive association between body weight and breast cancer risk among postmenopausal women. The cumulative exposure to estrogen throughout a woman's life is one of the significant risk factors for breast cancer. After menopause, adipose tissue is a major source of estrogen. Therefore, an increase in body fat after menopause is one of the possible explanations for the positive association of body weight with the development of breast cancer. To evaluate the impact of body weight on the risk of breast cancer, we need to consider the role of adipose tissue in the development and differentiation of normal mammary glands. Special attention should be paid to women in their twenties and/or during their lactation periods when the development of normal mammary glands is significant. Further studies are needed to investigate the association between BMI and breast cancer risk, considering the role of body fat in the development of mammary glands.
authors.affiliation: Unit for Medical Nutrition, Dept. of Healthcare, Tokyo Healthcare University.
authors.forename: Reiko
authors.initials: R
authors.lastname: Suzuki
authors.forename: Shigehira
authors.initials: S
authors.lastname: Saji
mesh_terms: D001835:Body Weight; D001943:Breast Neoplasms / Q000209:etiology*; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000254:growth & development; D009765:Obesity / Q000150:complications*; D017698:Postmenopause; D017697:Premenopause; D012307:Risk Factors; D013851:Thinness / Q000209:etiology*