Body mass and endometrial cancer risk by hormone replacement therapy and cancer subtype.
Epidemiologic studies unequivocally show that greater body mass increases the risk of endometrial cancer, but whether risk varies by use of postmenopausal hormone therapy (HT), location of fat deposition, or cancer subtype is still unclear. We examined these associations among 33,436 postmenopausal women in the Cancer Prevention Study II Nutrition Cohort, who completed questionnaires on diet, lifestyle, and medical history at baseline in 1992. A total of 318 cases were eligible through June 2003. Cox-proportional hazards analyses were used to estimate multivariate-adjusted rate ratios (RR). As expected, adult body mass index (BMI) was a strong predictor of risk [RR, 4.70; 95% confidence interval (CI), 3.12-7.07 for BMI 35+ versus 22.5-25.0, P trend < 0.0001]. Use of estrogen plus progestin postmenopausal HT modified the association. Among never-users, risk was significantly linear across the entire range of BMI examined (RR, 0.51; 95% CI, 0.29-0.92 for <22.5 versus 22.5-25.0; RR, 4.41; 95% CI, 2.70-7.20 for > or =35 versus 22.5-25.0, P trend < 0.0001), but among ever estrogen plus progestin users, the association was not significant (P trend = 1.0; P interaction < 0.0001). We observed no difference in risk according to tendency for central versus peripheral fat deposition. Greater BMI (> or =30 versus <25.0) increased risk of both "type I" (classic estrogen pathway, RR, 4.22; 95% CI, 3.07-5.81) and "type II" (serous, clear cell, and all other high grade) cancers (RR, 2.87; 95% CI, 1.59-5.16). The increased risk of endometrial cancer across the range of BMI in women who never used postmenopausal HT stresses the need to prevent both overweight and obesity in women.
McCullough
Marjorie L
ML
Epidemiology and Surveillance Research, American Cancer Society, 250 Williams Street, Atlanta, GA 30303-1002, USA. marji.mccullough@cancer.org
Patel
Alpa V
AV
Patel
Roshni
R
Rodriguez
Carmen
C
Feigelson
Heather Spencer
HS
Bandera
Elisa V
EV
Gansler
Ted
T
Thun
Michael J
MJ
Calle
Eugenia E
EE
D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D016889:Endometrial Neoplasms / Q000453:epidemiology*; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000627:therapeutic use; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009765:Obesity; D011372:Progestins / Q000627:therapeutic use; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
D004967:Estrogens; D011372:Progestins