Oral Contraceptives and The Risk of Cervical Cancer
Long-term use of oral contraceptives and a high number of children increase the risk of cervical cancer in women with HPV infection.
Cancer of the cervix uteri is the third most frequent cancer in women worldwide, and the most common one in large parts of Africa, Latin America and Asia. Out of approximately 200,000 yearly deaths from this cancer, 80% occur in developing countries.
A virus, the human papillomavirus (HPV), has been found in virtually all cervical cancers and is now considered to be a necessary cause of this disease. In the majority of women, however, HPV infections are harmless. Some co-factors should, therefore, exist which increase the chance of persistence and/or of progression of HPV infection into cancer.
The identification of such co-factors requires an adequate control for the strong effect of HPV and a large study population. These two prerequisites were fulfilled in a multi-centric study carried out between 1985 and 1993 by the International Agency for Research on Cancer (IARC) in 10 countries. This study included nearly 2000 women with cervical cancer and a similar number of healthy control women recruited from high-risk areas for cervical cancer in Colombia, Brazil, Peru, Paraguay, and Morocco, from intermediate-risk areas in Thailand and the Philippines, and from Spain, a low-risk country. To take into account the strong causative effect of HPV, the main analyses were restricted to women who were infected by the virus.
Two reports from the IARC study are published on 30 March in The Lancet. One concerns the use of oral contraceptives (Victor Moreno, from the Catalan Institute of Oncology, Barcelona, Spain, and colleagues), while the other analyzes the effects of reproductive factors, especially the number of children (Nubia Mu