The efficacy of cytobrush cytological sampling in anal dysplasia screening

Abstract

Anal cancer is rare among men in general but is at least 17 times more common among men who have sex with men (MSM). Anal smear cytology with Papanicolaou staining has been proposed as a screening test, as for cervical cancer. The aim of this study was to look at the effectiveness of different cytology sampling methods. MSM presenting to Cairns Sexual Health Service were invited to participate. Anal smears were taken either with a cotton/Dacron swab blindly from the ano-rectal junction or a cytobrush with the visualisation of a proctoscope. Of 213 smears, 116 (62%) showed some abnormalities. Further analysis of the abnormal smears showed that 27.3% were low-grade squamous intra-epithelial lesion (LSIL), 25.7% high-grade intra-epithelial lesion (HSIL) and 9.1% atypical squamous cells of undetermined significance (ASCUS). Of 75 smears taken with a cytobrush 2.7% resulted in an inadequate specimen, compared to 17.3% of 127 smears taken with cotton/ Dacron swabs (P = 0.002). There was also a tendency for less ASCUS (2.3% v. 12.4%, P = 0.058). Smears taken with cytobrush yielded as low a percentage of inadequate specimens as cervical smears in a large state-based registry (2.7% v. 1.4%, P = 0.35). We conclude that the cytobrush is an effective implement for cytological sampling of the anorectal junction and possibly superior to cotton or Dacron swabs. Due to the sharp tips of the former, insertion with the direct visualisation of a proctoscope is recommended.<br />