Research papers: Lifestyle: SmokingThe influence of smoking and other cofactors on the time to onset to cervical cancer in a southern European populationMatos, Aa b; Moutinho, Jb; Pinto, Da; Medeiros, RaAuthor Information aMolecular Oncology Unit bGynaecology Department, Instituto Português de Oncologia, Porto 4200–072, Portugal Correspondence to: Rui Medeiros, PhD, Instituto Português de Oncologia-Porto (Laboratórios – Piso 4), R. Dr. António Bernardino de Almeida, 4200–072 Porto; Portugal Tel: +35 1 22 5502011 (ext. 5022); fax: +35 1 22 5026489; e-mail: email@example.com Received 12 September 2004 Accepted 26 October 2004 European Journal of Cancer Prevention: October 2005 - Volume 14 - Issue 5 - p 485-491 doi: 10.1097/01.cej.0000174780.44260.32 Buy Metrics Abstract Cervical cancer is a complex and multifactorial disease. Although there are substantial data supporting the causative role of persistent human papillomavirus (HPV) infection in the development of cervical cancer, the complete course of the disease has never been completely understood. Several risk cofactors have been suggested with controversial results. Portugal has the highest incidence of squamous cell carcinoma (SCC) within western Europe and there are no known studies regarding the role of cofactors in SCC. The aim of our study was to evaluate the role of smoking, sexual behaviour, reproductive and contraceptive history, in the time-to-onset (TTO) of severe cervical lesions (HGSIL/SCC) in the Portuguese population. We verified that age of first sexual intercourse under 18 years (odds ratio (OR) 2.8), pregnancy (OR 2.9), first pregnancy under 21 years (2.6), number of pregnancies (OR 2.3–5.4) and parity (OR 1.9–5.7) are risk factors in the development of cervical neoplasia. Smoke exposure index (SEI) was significantly different (P=0.002) between cases and controls. Our results regarding time-to-onset demonstrate that smoking (P<0.001, log rank test), number of sexual partners (P<0.001, log rank test) and use of oral contraceptives (P<0.001, log rank test) are important determinants in the earlier onset of severe cervical lesions. Using this approach, our findings may help to clarify the role of smoking and other cofactors in the persistence and progression of cervical lesions. © 2005 Lippincott Williams & Wilkins, Inc.