Introduction/Background ASC-US and LSIL smears are diagnosed frequently in cervical screening programs. Only 5–15% of the low-grade cervical abnormalities may develop into high grade lesions, and about 1% in cervical cancer. Compliance to recommended follow-up after ASC-US/LSIL is known to variate.

Objective To examine the risk of developing CIN3 or cervical cancer after ASC-US/LSIL cytology, in relation to compliance with recommended follow-up.

Methodology Retrospective population-based 1:3 frequency matched cohort study comparing women with ASC-US/LSIL non-compliant (cases) to women compliant (controls) to the recommended follow-up. Women, diagnosed with ASC-US/LSIL between 1 January 2000 and 31 December 2005, were selected from and matched by the Dutch Nationwide Pathology Databank (Palga). Women with a prior history of CIN3 or cervical cancer were excluded from the study. Cases of CIN1–3 and cervical cancer were identified until 31 May 2020.

Results Mean follow up after ASCUS/LSIL was 12 years (2–20 years). Of 9,616 women not compliant to follow-up, 481 women (5.0%) developed CIN3 and 3 women (0.03%) cervical cancer. Of 28,829 women compliant to follow-up, 1192 women (4.13%) developed CIN3 and 11 women (0.04%) developed cervical cancer. Women compliant to follow up were significantly more often (>15 times more) treated for CIN1/2 (14.8% against 0.8%), had significantly less often CIN 3, and had a significant shorter time to their CIN 3 diagnosis.

Conclusion Cervical cancer incidence for women with an ASC-US/LSIL cervical smear result was not affected by compliance to follow-up. However, women who were non-compliant to follow-up had a higher incidence of detected CIN3, while excisional rates in women compliant to follow-up were significantly higher, indicating overtreatment of CIN1 and CIN2. Further research is warranted to optimize follow-up strategies for women with anASC-US/LSIL in a both primary cytological and HPV screening settings.

Disclosures None.