title: The histology of ovarian cancer: worldwide distribution and implications for international survival comparisons (CONCORD-2).
abstract: OBJECTIVE
  Ovarian cancers comprise several histologically distinct tumour groups with widely different prognosis. We aimed to describe the worldwide distribution of ovarian cancer histology and to understand what role this may play in international variation in survival.
  
  
  METHODS
  The CONCORD programme is the largest population-based study of global trends in cancer survival. Data on 681,759 women diagnosed during 1995-2009 with cancer of the ovary, fallopian tube, peritoneum and retroperitonum in 51 countries were included. We categorised ovarian tumours into six histological groups, and explored the worldwide distribution of histology.
  
  
  RESULTS
  During 2005-2009, type II epithelial tumours were the most common. The proportion was much higher in Oceania (73.1%), North America (73.0%) and Europe (72.6%) than in Central and South America (65.7%) and Asia (56.1%). By contrast, type I epithelial tumours were more common in Asia (32.5%), compared with only 19.4% in North America. From 1995 to 2009, the proportion of type II epithelial tumours increased from 68.6% to 71.1%, while the proportion of type I epithelial tumours fell from 23.8% to 21.2%. The proportions of germ cell tumours, sex cord-stromal tumours, other specific non-epithelial tumours and tumours of non-specific morphology all remained stable over time.
  
  
  CONCLUSIONS
  The distribution of ovarian cancer histology varies widely worldwide. Type I epithelial, germ cell and sex cord-stromal tumours are generally associated with higher survival than type II tumours, so the proportion of these tumours may influence survival estimates for all ovarian cancers combined. The distribution of histological groups should be considered when comparing survival between countries and regions.
authors.affiliation: Cancer Survival Group, London School of Hygiene & Tropical Medicine, London, UK. Electronic address: Melissa.Matz@LSHTM.ac.uk.
authors.forename: Melissa
authors.initials: M
authors.lastname: Matz
authors.affiliation: Cancer Survival Group, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Michel P
authors.initials: MP
authors.lastname: Coleman
authors.affiliation: Department of Preventive and Predictive Medicine, Analytical Epidemiology and Health Impact Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Milena
authors.initials: M
authors.lastname: Sant
authors.affiliation: Department of Epidemiology, Regional Health Council, IMIB, Arrixaca, Murcia, Spain, CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain, Department of Health and Social Sciences, Murcia University, Murcia, Spain.
authors.forename: Maria Dolores
authors.initials: MD
authors.lastname: Chirlaque
authors.affiliation: Department of Registration, Netherlands Comprehensive Cancer Organisation, Utrecht, The Netherlands.
authors.forename: Otto
authors.initials: O
authors.lastname: Visser
authors.affiliation: The Royal Marsden NHS Foundation Trust, London, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Gore
authors.affiliation: Cancer Survival Group, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Claudia
authors.initials: C
authors.lastname: Allemani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000077216:Carcinoma, Ovarian Epithelial; D005260:Female; D006801:Humans; D008875:Middle Aged; D009373:Neoplasms, Germ Cell and Embryonal / Q000401:mortality / Q000473:pathology; D009375:Neoplasms, Glandular and Epithelial / Q000401:mortality / Q000473:pathology; D010051:Ovarian Neoplasms / Q000401:mortality / Q000473:pathology*; D018312:Sex Cord-Gonadal Stromal Tumors / Q000401:mortality / Q000473:pathology
keywords: Epidemiology; Histology; Morphology; Ovarain cancer; Worldwide