Increased incidence of cervical intraepithelial neoplasia grade 3 and human papillomavirus infection at a family planning clinic.

A five-fold increase in the incidence of histologically-proven cervical intraepithelial neoplasia grade 3 (CIN3) was observed for patients attending the Christchurch family planning clinic in 1985 compared with the preceding three years. There were 51 new cases in 1985 and a yearly average of 9.3 between 1982 and 1984. There was an increase also in cervical smears showing evidence of human papillomavirus (HPV) infection. The time interval between the last normal smear and the diagnosis of CIN3 was short, averaging 2.3 years. CIN3 patients were young (average 28.9 years); they had a high average number of sexual partners (10.1). These findings support the theory of a sexually transmitted precursor to the development of CIN3. The 1985 surge in CIN3 may reflect an increased prevalence of this oncogenic agent. The aim of screening is to prevent invasive cervical carcinoma. Annual smears should therefore be considered for young sexually-active women in view of the short time interval between normal smears and the development of CIN3.