title: Type I and II endometrial cancers: have they different risk factors?
abstract: OBJECTIVE
  Endometrial cancers have long been divided into estrogen-dependent type I and the less common clinically aggressive estrogen-independent type II. Little is known about risk factors for type II tumors because most studies lack sufficient cases to study these much less common tumors separately. We examined whether so-called classical endometrial cancer risk factors also influence the risk of type II tumors.
  
  
  METHODS
  Individual-level data from 10 cohort and 14 case-control studies from the Epidemiology of Endometrial Cancer Consortium were pooled. A total of 14,069 endometrial cancer cases and 35,312 controls were included. We classified endometrioid (n = 7,246), adenocarcinoma not otherwise specified (n = 4,830), and adenocarcinoma with squamous differentiation (n = 777) as type I tumors and serous (n = 508) and mixed cell (n = 346) as type II tumors.
  
  
  RESULTS
  Parity, oral contraceptive use, cigarette smoking, age at menarche, and diabetes were associated with type I and type II tumors to similar extents. Body mass index, however, had a greater effect on type I tumors than on type II tumors: odds ratio (OR) per 2 kg/m(2) increase was 1.20 (95% CI, 1.19 to 1.21) for type I and 1.12 (95% CI, 1.09 to 1.14) for type II tumors (P heterogeneity < .0001). Risk factor patterns for high-grade endometrioid tumors and type II tumors were similar.
  
  
  CONCLUSIONS
  The results of this pooled analysis suggest that the two endometrial cancer types share many common etiologic factors. The etiology of type II tumors may, therefore, not be completely estrogen independent, as previously believed.
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California, 1450 Biggy St, Los Angeles, CA 90033, USA. vsetiawa@usc.edu
authors.forename: Veronica Wendy
authors.initials: VW
authors.lastname: Setiawan
authors.forename: Hannah P
authors.initials: HP
authors.lastname: Yang
authors.forename: Malcolm C
authors.initials: MC
authors.lastname: Pike
authors.forename: Susan E
authors.initials: SE
authors.lastname: McCann
authors.forename: Herbert
authors.initials: H
authors.lastname: Yu
authors.forename: Yong-Bing
authors.initials: YB
authors.lastname: Xiang
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
authors.forename: Nicolas
authors.initials: N
authors.lastname: Wentzensen
authors.forename: Noel S
authors.initials: NS
authors.lastname: Weiss
authors.forename: Penelope M
authors.initials: PM
authors.lastname: Webb
authors.forename: Piet A
authors.initials: PA
authors.lastname: van den Brandt
authors.forename: Koen
authors.initials: K
authors.lastname: van de Vijver
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Thompson
authors.forename: Brian L
authors.initials: BL
authors.lastname: Strom
authors.forename: Amanda B
authors.initials: AB
authors.lastname: Spurdle
authors.forename: Robert A
authors.initials: RA
authors.lastname: Soslow
authors.forename: Xiao-ou
authors.initials: XO
authors.lastname: Shu
authors.forename: Catherine
authors.initials: C
authors.lastname: Schairer
authors.forename: Carlotta
authors.initials: C
authors.lastname: Sacerdote
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Rohan
authors.forename: Kim
authors.initials: K
authors.lastname: Robien
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Risch
authors.forename: Fulvio
authors.initials: F
authors.lastname: Ricceri
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Rebbeck
authors.forename: Radhai
authors.initials: R
authors.lastname: Rastogi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Prescott
authors.forename: Silvia
authors.initials: S
authors.lastname: Polidoro
authors.forename: Yikyung
authors.initials: Y
authors.lastname: Park
authors.forename: Sara H
authors.initials: SH
authors.lastname: Olson
authors.forename: Kirsten B
authors.initials: KB
authors.lastname: Moysich
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Miller
authors.forename: Marjorie L
authors.initials: ML
authors.lastname: McCullough
authors.forename: Rayna K
authors.initials: RK
authors.lastname: Matsuno
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Magliocco
authors.forename: Galina
authors.initials: G
authors.lastname: Lurie
authors.forename: Lingeng
authors.initials: L
authors.lastname: Lu
authors.forename: Jolanta
authors.initials: J
authors.lastname: Lissowska
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Liang
authors.forename: James V
authors.initials: JV
authors.lastname: Lacey
authors.forename: Laurence N
authors.initials: LN
authors.lastname: Kolonel
authors.forename: Brian E
authors.initials: BE
authors.lastname: Henderson
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
authors.forename: Niclas
authors.initials: N
authors.lastname: Håkansson
authors.forename: Marc T
authors.initials: MT
authors.lastname: Goodman
authors.forename: Mia M
authors.initials: MM
authors.lastname: Gaudet
authors.forename: Montserrat
authors.initials: M
authors.lastname: Garcia-Closas
authors.forename: Christine M
authors.initials: CM
authors.lastname: Friedenreich
authors.forename: Jo L
authors.initials: JL
authors.lastname: Freudenheim
authors.forename: Jennifer
authors.initials: J
authors.lastname: Doherty
authors.forename: Immaculata
authors.initials: I
authors.lastname: De Vivo
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Courneya
authors.forename: Linda S
authors.initials: LS
authors.lastname: Cook
authors.forename: Chu
authors.initials: C
authors.lastname: Chen
authors.forename: James R
authors.initials: JR
authors.lastname: Cerhan
authors.forename: Hui
authors.initials: H
authors.lastname: Cai
authors.forename: Louise A
authors.initials: LA
authors.lastname: Brinton
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Kristin E
authors.initials: KE
authors.lastname: Anderson
authors.forename: Hoda
authors.initials: H
authors.lastname: Anton-Culver
authors.forename: Leo J
authors.initials: LJ
authors.lastname: Schouten
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Horn-Ross
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D000328:Adult; D000367:Age Factors; D000368:Aged; D001707:Biopsy, Needle; D018269:Carcinoma, Endometrioid / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D003276:Contraceptives, Oral / Q000009:adverse effects; D016208:Databases, Factual; D003920:Diabetes Mellitus / Q000453:epidemiology; D018572:Disease-Free Survival; D016889:Endometrial Neoplasms / Q000453:epidemiology* / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D009765:Obesity / Q000453:epidemiology; D016017:Odds Ratio; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012907:Smoking / Q000453:epidemiology; D016019:Survival Analysis
chemical_list: D003276:Contraceptives, Oral