Anal Cytology: Institutional Statistics, Correlation With Histology, and Development of Multidisciplinary Screening...

The incidence of anal cancer in the United States is on the rise in high-risk populations. The anal Papanicolaou test (APT) is advocated as a screening tool, in addition to digital rectal examination and high-resolution anoscopy.

To review our experience and the current literature to create, in cooperation with clinicians, a standardized screening and treatment algorithm given our large volume of APTs.

All APTs collected between January 2013 and June 2015 were reviewed and correlated with follow-up/concurrent biopsy diagnoses, and clinical and social history. In total, 1417 APTs were performed on 1185 patients and APT results were as follows: 17.4% (247 of 1417) unsatisfactory; 27.9% (395 of 1417) negative; 19.5% (276 of 1417) atypical squamous cells of undetermined significance (ASC-US); 24.1% (342 of 1417) low-grade squamous intraepithelial lesion (LSIL); 3.6% (51 of 1417) atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (HSIL) (ASC-H); and 7.5% (106 of 1417) HSIL. In total 376 cases (26.5%) had concurrent/follow-up biopsy. Review of all unsatisfactory cases with squamous intraepithelial lesion (SIL) on biopsy showed LSIL in 19.2% (5 of 26). Anal Papanicolaou test with cytologic abnormality (ASC-US+) had an 83.8% (315 of 376) rate of biopsy-proven disease, and sensitivity was higher (92%) for high-grade anal intraepithelial neoplasia or worse (AIN2+). Overall detection of AIN2+ using ASC-US+ showed specificity of 26%, negative predictive value of 92%, and positive predictive value of 26%.

Anal cytology has a high abnormal rate (54.7%) and sensitivity but poor correlation with histologic grade. High unsatisfactory rate indicates need for improvement in sampling with 68.4% of cases having SIL on biopsy. Multidisciplinary effort led to improvements in sampling, cytologic interpretation, and development of a standardized management algorithm.