Is there a gain in chromosome 3q in the pathway to anal cancer?

Background: Chromosome 3q gain has been identified in human papillomavirus-infected cervical cancer cells.

Objective: We sought to identify the presence of chromosomal 3q gain in anal neoplasia.

Design: This was a retrospective cohort.

Settings: The study was conducted in a group colorectal surgery practice.

Patients: Fifty-two patients with no dysplasia, low-grade dysplasia, high-grade dysplasia, or anal cancer were studied.

Interventions: Pairs of biopsy specimens were paraffin embedded and reviewed. One of each slide pair was stained with hematoxylin and eosin and the second processed for fluorescence in situ hybridization. The hybridized set was deparaffinized first and then hybridized with a probe for the chromosome 3q26 region. Then, slides were scanned using an automated fluorescence microscopy system that analyzed defined areas of the tissue to enumerate all of the nuclei for hybridized probe signals to detect chromosome 3q gain.

Main Outcome Measures: We measured for gain in chromosome 3q26.

Results: We identified chromosome 3q gain in 7 (78%) of 9 patients with squamous-cell cancer, 8 (53%) of 15 high-grade dysplasia samples, 0 of 12 low-grade dysplasia samples, and 0 of 16 samples with no dysplasia. The sensitivity for high-grade or invasive neoplasia was 58%, with a specificity of 100%. The positive predictive value of the test was 100% for detecting high-grade dysplasia and/or squamous-cell cancer from no dysplasia, and the negative predictive value of the test was 62%.

Limitations: This study was limited by its small sample size and retrospective design.

Conclusions: Chromosome 3q gain represents an important shared pathway to tumorigenesis in cervical and anal neoplasia. Multiple potential diagnostic roles exist for this easily performed test in the evaluation of anal neoplasia.