Prospective evaluation of risk of cervical cancer after cytological evidence of human papilloma virus infection.

846 women with cytological evidence of human papillomavirus infection on their Papanicolaou smears in 1979 were followed for the subsequent development of cervical malignant disorders. Carcinoma-in-situ developed in 30 women during the next 6 years, compared with an expected number of 1.9 by general population incidence figures, giving a relative risk of 15.6. The risk was greatly increased (38.7) in women younger than 25 years when the cytological diagnosis of human papillomavirus infection was made.