title: Short-term weight gain and breast cancer risk by hormone receptor classification among pre- and postmenopausal women.
abstract: Obesity is well established as a cause of postmenopausal breast cancer incidence and mortality. In contrast, adiposity in early life reduces breast cancer incidence. However, whether short-term weight change influences breast cancer risk is not well known. We followed a cohort of 77,232 women from 1980 to 2006 (1,445,578 person-years), with routinely updated risk factor information, documenting 4196 incident cases of invasive breast cancer. ER and PR status were obtained from pathology reports and medical records yielding a total of 2033 ER+/PR+ tumors, 595 ER-/PR- tumors, 512 ER+/PR- tumors. The log incidence breast cancer model was used to assess the association of short-term weight gain (over past 4 years) while controlling for average BMI before and after menopause. Short-term weight change was significantly associated with breast cancer risk (RR 1.20; 95 % CI 1.09-1.33) for a 4-year weight gain of ≥15 lbs versus no change (≤5 lbs) (P_trend < 0.001). The association was stronger for premenopausal women (RR 1.38; 95 % CI 1.13-1.69) (P_trend = 0.004) than for postmenopausal women (RR 1.10; 95 % CI 0.97-1.25) (P_trend = 0.063). Short-term weight gain during premenopause had a stronger association for ER+/PR- (RR per 25 lb weight gain = 2.19; 95 % CI 1.33-3.61, P = 0.002) and ER-/PR- breast cancer (RR per 25 lb weight gain = 1.61; 95 % CI 1.09-2.38, P = 0.016) than for ER+/PR+ breast cancer (RR per 25 lb weight gain = 1.13; 95 % CI 0.89-1.43, P = 0.32). There are deleterious effects of short-term weight gain, particularly during pre-menopause, even after controlling for average BMI before and after menopause. The association was stronger for ER+/PR- and ER-/PR- than for ER+/PR+ breast cancer.
authors: Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA, 02115, USA, stbar@channing.harvard.edu.
authors: Bernard
authors: B
authors: Rosner
authors: A Heather
authors: AH
authors: Eliassen
authors: Adetunji T
authors: AT
authors: Toriola
authors: Susan E
authors: SE
authors: Hankinson
authors: Walter C
authors: WC
authors: Willett
authors: Loki
authors: L
authors: Natarajan
authors: Graham A
authors: GA
authors: Colditz
mesh_terms: D000465:Algorithms; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000378:metabolism; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D017697:Premenopause; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D012307:Risk Factors; D013997:Time Factors; D015430:Weight Gain
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone