Objective: causal relation between high risk Papilloma virus and cervical carcinoma is definitely ascertained. HPV test is suggested both as primary screening test and as triage test for selecting women who should undergo colposcopy examination. Evidence is clear for triage after ASC-US cytology. A recent study suggested the implementation after LSIL cytology in women 35 or older but the issue is controversial.We present a pilot study on the implementation of HPV test triage in the framework of cervical cancer screening. The study was conducted in respect to: participation, predictive value, and cost analysis, separately for ASC-US and LSIL cytology.
Design: HPV test was offered to women with Pap test result ASC-US or LSIL (35 and over), as an add-on to the "Prevenzione serena Screening Program" protocol. All samples were analyzed in the same specialized laboratory. HPV positive women were invited to colposcopy, negative will be invited at the scheduled interval for negative screening tests.
Setting and participants: Piedmont (NW Italy), LHAs of Novara and Verbano. In the 1-year study period 15,614 Pap tests were performed: 153 women were eligible for the triage.
Main outcome measures: Participation at HPV test, HPV test results, costs.
Results: ninety two percent of women invited to HPV test actually participated: 66.9% of them were positive (52.8% after ASC-US and 82.8% after LSIL). Regarding colposcopy and histological results, CIN2+ were 9.4% of positive HPV tests in ASC-US group and 17.1% in LSIL group. Cost analysis showed limited differences between triage (offered after ASC-US and LSIL cytology) and traditional protocol. Triage is economically convenient when limited to women with ASC-US cytology.
Conclusion: the pilot study demonstrated the feasibility of adding a triage phase with HPV test in cervical cancer screening protocol. Additional cost is balanced by the saving due to the reduction in the number of colposcopy exams: the process is economically convenient when limited to women with ASC-US cytology. When extended to LSIL cytology the marginal cost increases because of the higher prevalence of HPV positive results and total cost of triage with HPV test is close to the cost of immediate colposcopy referral.