Factors associated with reduced accuracy in Papanicolaou tests for patients with invasive cervical cancer

Abstract

Background: Recent proposals to lengthen the interval in cervical cancer screening highlight the importance of the accurate interpretation of screening tests. Tumor debris present in Papanicolaou (Pap) tests from women with invasive cancer is known to hamper interpretation. The current study evaluated limiting factors in Pap tests from women with invasive cervical cancer.

Methods: A total of 3003 women with the spectrum of cervical lesions who had ThinPrep (Hologic Inc, Marlborough, Mass) Pap and human papillomavirus (HPV) genotyping tests performed were grouped by their most severe histologic diagnosis. Cytologic and HPV results were analyzed by cross-sectional analysis.

Results: The unsatisfactory rate of cytology specimens from patients with cancer (3.1%) was significantly higher than those from patients with cervical intraepithelial neoplasia of type 3 or less (0.8%) (P < .001). The percentage of samples with qualified adequacy was 34.8% in specimens from patients with cancer compared with only 3.6% from specimens from those without cancer (P < .001). The unsatisfactory and qualified adequacy rates were higher in squamous cancers compared with adenocarcinomas. However, adenocarcinomas were identified less frequently than squamous cancers (37.0% vs 61.7%) in the Pap tests. HPV tests were positive in 84.4% of unsatisfactory cases including 8 of 9 cancer cases, although 8.5% of cancers tested negative for HPV.

Conclusions: Unsatisfactory and suboptimal ThinPrep Pap tests were increased in cancer cases compared with lesser histologic diagnoses. This was found to be particularly true for squamous cancers. Specimens from adenocarcinomas had fewer adequacy problems but were less frequently recognized as malignant. HPV tests were positive in the majority of unsatisfactory Pap tests in women with carcinoma, suggesting that HPV testing in women aged > 30 years can help to identify high-risk women with unsatisfactory Pap tests.

Keywords: cancer screening; cervical neoplasms; cervical smears; cytodiagnosis; human papillomavirus DNA tests.