Risk factors for ovarian cancer histotypes Francesca Chiaffarino a , Fabio Parazzini a,b , Cristina Bosetti a , Silvia Franceschi c , Renato Talamini d , Vincenzo Canzonieri e , Maurizio Montella f , Valerio Ramazzotti g , Silvia Franceschi g , Carlo La Vecchia a,h, * a Istituto di Ricerche Farmacologiche ‘Mario Negri’, Via Eritrea, 62, 20157 Milan, Italy b Prima Clinica Ostetrico Ginecologica, Universita` degli Studi di Milano, 20129 Milan, Italy c International Agency for Research on Cancer, 69372 Lyon, Cedex 08, France d Centro di Riferimento Oncologico – IRCCS, 33081 Aviano (PN), Italy e Divisione di Anatomia Patologica, Centro di Riferimento Oncologico, Aviano (PN), Italy f Istituto Tumori ‘Fondazione Pascale’, 80131 Napoli, Italy g Servizio Integrato di Epidemiologia e Sistemi Informativi, Istituto Nazionale Tumori ‘Regina Elena’, 00144 Rome, Italy h Istituto di Statistica Medica e Biometria, Universita` degli Studi di Milano, 20133 Milan, Italy ARTICLE INFO Article history: Received 12 January 2007 Accepted 15 January 2007 Available online 21 March 2007 Keywords: Ovarian cancer Epidemiology Histological types Reproductive factors Hormones Family history Physical activity ABSTRACT To analyse the risk factors for different histologic types of ovarian cancer, we conducted a case-control study. The cases included 750 women with incident, histologically confirmed invasive epithelial ovarian cancer subdivided into: 493 serous, 81 mucinous, 78 endometri- oid, and 98 other histologies. The controls included 2411 women admitted to the same hos- pitals as cases. The odds ratios for women with three or more births, in comparison with nulliparae, were 0.6 for serous, 0.4 for endometrioid, 1.0 for mucinous and 0.7 for other his- tological types of ovarian cancer. Family history of ovarian/breast cancer was associated to the risk of all ovarian cancer types, except mucinous ones. Selected dietary factors were less strongly directly (meat and starch), or inversely (fish and vitamin E) related to mucin- ous than to other histological types of ovarian cancer. High occupational physical activity was inversely related to the risk of ovarian cancer, with no heterogeneity across histologies. In conclusion, the association of reproductive factors and of selected dietary habits was weaker for mucinous ovarian cancer than for other histologic types. Ó 2007 Elsevier Ltd. All rights reserved. 1. Introduction Epithelial cancers account for about 90% of ovarian cancers. They include four major histologic types: serous (the most common subtype, accounting for about 50% of all epithelial ovarian cancers), mucinous, endometrioid, clear cell and other less common types. 1 The potentially different impact of risk factors for ovarian cancer on different histotypes of the disease has not been adequately investigated. Some evidence showed that mucin- ous ovarian cancer may in some aspects differ from other his- totypes 2–4 : a protective role for reproductive factors was found for serous and other non-mucinous ovarian cancers, but less consistently for mucinous ones. However, other stud- ies did not show any difference. 5–7 In a paper on this issue, based on a previous Italian dataset, parity and oral contracep- tive (OC) use were inversely related to the risk of serous and endometrioid, but not of mucinous ovarian cancer. 8 0959-8049/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejca.2007.01.035 * Corresponding author: Address: Istituto di Ricerche Farmacologiche ‘Mario Negri’, Via Eritrea, 62, 20157 Milan, Italy. Tel.: +39 2 39014328; fax: +39 2 33200231. E-mail address: lavecchia@marionegri.it (C. La Vecchia). EUROPEAN JOURNAL OF CANCER 43 (2007) 1208 – 1213 available at www.sciencedirect.com journal homepage: www.ejconline.com