Human papillomavirus infection and the risk of cervical cancer in Japan

Infection with a high-risk human papillomavirus (HPV) is established as a major risk factor for cervical cancer. In Japan, eight HPV genotypes (16, 18, 31, 33, 35, 45, 52 and 58) confer a much higher risk of cervical cancer and its immediate premalignant lesions (cervical intraepithelial neoplasia grade 3 [CIN 3]) than do other high-risk and the low-risk HPV types. However, only a small fraction of infected women develop CIN 3 or invasive cervical cancer, suggesting the involvement of additional cofactors in cervical carcinogenesis. A multicenter prospective cohort study of Japanese women with low-grade cervical abnormalities has demonstrated that tobacco smoking is significantly associated with an increased risk of persistent low-grade cervical lesions, while the presence of human leukocyte antigen Class II DRB1*1302 protects against progression to CIN 3. Understanding the epidemiology of HPV infections and cervical cancer may improve prevention and lead to novel clinical management strategies for cervical precursor lesions. Viral and host factors that affect the risk of cervical cancer are discussed in this review.