title: Body size in different periods of life and breast cancer risk in post-menopausal women.
abstract: Adult obesity has been associated with an increased risk of post-menopausal breast cancer, but it is unclear whether this relationship reflects a causal role of obesity during childhood and adolescence, of weight gain during adult life or of adult obesity per se. In a population-based case-control study in all of Sweden, we included 3,345 (84% of all eligible) women aged 50-74 years with invasive breast cancer, and 3,454 (82% of all selected) controls of similar age. Mailed questionnaires and telephone interviews were used to collect detailed information on anthropometric measures. Odds ratios were estimated through multiple logistic regression. Women with the leanest somatotype at age 7 had about a 3-fold higher risk of breast cancer than the most obese (P for trend 0.0009). A suggested protective effect of a high body mass at age 18 and a detrimental influence of body mass 1 year prior to data collection largely reflected the effect of weight gain after age 18, a strong predictor of breast cancer risk. Among women at least 20 years post menopause, those who had gained 30 kg or more since age 18 had an odds ratio of 2.04 (95% confidence interval 1.20-3.48) of breast cancer compared with those who had maintained their weight unchanged. The effect of weight gain was unequivocal among non-users but not among users of hormone replacement therapy. Our findings have important implications, suggesting weight preservation as a means for prevention of post-menopausal breast cancer as well as a causal role of childhood body build in breast cancer etiology.
authors.affiliation: Department of Medical Epidemiology, Karolinska Institutet, Stockholm, Sweden. Cecilia.Magnusson@mep.ki.se
authors.forename: C
authors.initials: C
authors.lastname: Magnusson
authors.forename: J
authors.initials: J
authors.lastname: Baron
authors.forename: I
authors.initials: I
authors.lastname: Persson
authors.forename: A
authors.initials: A
authors.lastname: Wolk
authors.forename: R
authors.initials: R
authors.lastname: Bergström
authors.forename: D
authors.initials: D
authors.lastname: Trichopoulos
authors.forename: H O
authors.initials: HO
authors.lastname: Adami
mesh_terms: D000367:Age Factors; D000368:Aged; D001827:Body Height; D001835:Body Weight; D001943:Breast Neoplasms / Q000209:etiology*; D016022:Case-Control Studies; D015914:Estrogen Replacement Therapy; D006801:Humans; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause; D012307:Risk Factors; D013008:Somatotypes; D013548:Sweden / Q000453:epidemiology; D015430:Weight Gain