The Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study (ALTS) accumulated information regarding conventional and liquid-based Papanicolaou (Pap) cytology, 2 kinds of human papillomavirus (HPV) DNA testing, cervicography, and colposcopically directed biopsy. The prevalence of squamous cell carcinoma in these women, the efficacy of tests, and the time to detection were reviewed.
The ALTS data base was reviewed for all women with invasive carcinoma. All results of colposcopy, HPV testing, cytology, biopsies, and cervigrams were reviewed for all women in the ALTS trial who were diagnosed with squamous cell carcinoma.
There were 7 diagnoses of invasive cancer (all squamous cell) during the 2 years of the ALTS trial. Although the enrollment studies isolated many high-grade lesions, none of those results were diagnostic of the underlying carcinoma.
The prevalence of squamous cell carcinoma in the setting of atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion cytology interpretation appears to be low (approximately 1 per 1000 women in the ALTS trial). Many of the carcinomas were not visible on the ectocervix by cervicography or colposcopy, which may explain in part the paucity of atypical cells detected on the Pap tests and the finding that the presenting cytology, although abnormal, was never diagnostic of cancer. HPV DNA tests were positive in all 7 cancers. Type-specific testing identified HPV type 16 in 6 of 7 cancers and HPV type 18 in 1 of 7 cancers.