Triage of women with ASCUS and LSIL on Pap smear reports: management by repeat Pap smear, HPV DNA testing, or colposcopy?

BACKGROUND: The purpose of this study was to determine the efficacy of a repeat Papanicolaou (Pap) smear and the Hybrid Capture tube-based (HCT) HPV DNA test for detecting cervical intraepithelial neoplasia (CIN) grade 2 or 3 in women with recent atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion (LSIL) Pap smear reports.

METHODS: Women with a recent Pap smear report of ASCUS (n = 169) or LSIL (n = 110) had a repeat Pap smear, sampling of the cervix for HCT HPV DNA assay and a colposcopy examination. Data were evaluated using three different triage thresholds for colposcopy examination: a repeat Pap smear of persistent ASCUS or more severe dysplasia, a finding of persistent LSIL or more severe dysplasia, and a carcinogenic HPV test result.

RESULTS: The sensitivity, specificity, and positive and negative predictive values for detecting CIN 2/3 were 70%, 45%, 7%, and 96% for a repeat Pap smear using an ASCUS-positive threshold and 20%, 86%, 8%, and 94% for a repeat Pap smear using an LSIL-positive threshold, respectively, when women with an initial ASCUS Pap smear were considered. HPV testing for carcinogenic viruses alone or in combination with a repeat Pap smear (using ASCUS as a positive threshold) yielded results of 50%, 67%, 9%, and 96%, respectively, and 70%, 37%, 7%, and 95%, respectively, for detecting CIN 2/3. In women with an initial LSIL Pap smear, respective values for detecting CIN 2/3 by a repeat Pap smear with an ASCUS threshold were 92%, 26%, 14%, and 96%, and for an LSIL threshold 23%, 64%, 8%, and 86%, respectively. Hybrid Capture HPV testing alone or in combination with a repeat Pap smear yielded 69%, 43%, 14%, and 91%, respectively, and 100%, 21%, 14%, and 100%, respectively.

CONCLUSIONS: A Pap smear triage threshold restricted to LSIL or more severe dysplasia for women with prior ASCUS or LSIL Pap smear results was clearly ineffective for detecting high-grade cervical precancerous lesions. In contrast, when the repeat Pap smear triage threshold was expanded to include persistent ASCUS as abnormal, 83% of the women with CIN 2/3 were detected. Detection of carcinogenic HPV DNA using the HCT test was almost as sensitive for detecting CIN 2/3 as a solitary repeat Pap smear using an ASCUS or more severe positive threshold. Combining the HPV test with a repeat Pap smear did not significantly improve the sensitivity of cytology for detecting high-grade CIN. This study suggests that women with ASCUS and particularly LSIL Pap smears should be referred for a colposcopy examination until better triage methods become available.