Background: The 2001 Bethesda System category of atypical squamous cells (ASC) denotes changes suggestive, but inconclusive for, a squamous intraepithelial lesion (SIL). ASC is subcategorized as: 1) "undetermined significance (ASC-US)," when changes suggest low-grade or indeterminate-grade SIL and 2) "cannot exclude high-grade squamous intraepithelial lesion (ASC-H)," when a cancer precursor is suspected.
Methods: To better define the characteristics of ASC-H, the authors analyzed and compared human papillomavirus (HPV) testing data and outcomes after 2 years for participants in the Atypical Squamous Cells of Undetermined Significance Low-Grade SIL Triage Study (ALTS), a randomized trial of 5060 women.
Results: Among women with thin-layer cytology findings of ASC-H, 84% tested positive for HPV, 50% (95% confidence interval [95% CI], 41%-60%) were diagnosed with cervical intraepithelial neoplasia (CIN) type 2+, and 30% (95% CI, 22-39%) were diagnosed with CIN3+. Positive HPV tests and diagnoses of CIN2+ and CIN3+ were found to be more common among women with ASCH compared with those with ASC-US, but the highest frequencies were found to be associated with high-grade SIL. For women age < 35 years with ASC-H, HPV detection exceeded 85%, whereas only 4 of 10 women (40%) age >/=35 years tested positive for HPV (P = 0.009).
Conclusions: A finding of ASC-H seems to confer a substantially higher risk for CIN2+ and CIN3+ than ASC-US. Immediate colposcopy may be the appropriate management for young women with ASC-H, but the utility of HPV testing for managing older women with ASC-H requires additional study.
(c) 2006 American Cancer Society.