High risk HPV (hr-HPV) testing is being widely incorporated in cervical screening globally. Japan still recommends biennial Pap smears as the standard screening method. We conducted a 3yr prospective study to evaluate the usefulness of cytology and HPV testing (cotesting) with partial genotyping for HPV16/18. Here baseline data is presented.
Women aged 20-69yrs attending Hokkaido Cancer Society for cervical screening in 2014 were informed about the study. Consenting participants had a Pap test and an HPV test using the Cobas 4800 System (Roche Diagnostics) which detects HPV16, HPV18, and 12 other hr-HPVs. Age-specific hr-HPV prevalence and HPV 16/18 prevalence at 1st screening visit as well as detection rates of CIN2+ lesions in relation to HPV/cytology status within 12mth of the 1st visit were investigated. This study was approved by the IRB for clinical trials at Hokkaido University.
In total, 14,650 women were enrolled. The mean age of participants was 50.6yrs. Hr-HPV detection rates for women in their 20s, 30s, 40s, 50s, and 60s was 16.1%, 8.8%, 5.2%, 2.6% and 2.7%, respectively. Of these 36.6%, 32.9%, 18.4%, 16.8% and 24.6% were HPV16/18 positive. Abnormal cytology was found in 347 women (2.4%). By age group it was 8.2%, 4.4%, 3.4%, 1.4% and 0.7%, respectively. Detection of HPV 16/18 was significantly higher in CIN2+ cases compared to other hr-HPV types (Odds ratio 3.80, 95% Confidence Interval 2.4-5.9). Incidence of CIN2+ in women with NILM cytology was 13/99 women (13.1%) with HPV16/18 and 5 /353 women (1.4%) with other hr-HPV (p<0.001). One woman who was HPV18 positive with NILM cytology and an initial negative colposcopy, presented with adenocarcinoma at the 2nd colposcopy 5 months later.
Women HPV16/18 positive, even with negative cytology, are at a high risk for the development CIN2+ lesions within 12 months and should be recommended for colposcopy and directed biopsy with intensive follow-up. Prevalence of HPV 16/18 is highest in women in their 20s/30s and these women have an equally high-risk of CIN2+ lesions as women in their 40s/ 50s.