Cervical cancer

Cervical cancer is the fourth most common cancer in women worldwide, with more than 500,000 cases and 250,000 deaths per year. The disease is characterized by marked regional differences, with more than 80% of the cases and deaths occurring in developing countries. The etiology and natural history of the disease are very well studied, with persistent infection with one of thirteen human papillomavirus (HPV) types now considered to be a necessary cause. The molecular mechanisms have also been elucidated and are mediated mainly by the expression of viral oncogenes that interfere with cellular pathways. The two most common HPV types, namely HPV-16 and HPV-18, are associated with about 70% of all cases around the world. Immunologic (e.g., HIV infection), hormonal (e.g., high parity), environmental (e.g., smoking), and genetic (e.g., HLA type) cofactors determine the risk of persistence and cancer among women harboring HPV infection.