Brush cytology of colorectal malignancies.

Objective: To evaluate the specificity and sensitivity of brush cytology and biopsy in colorectal malignancies.

Methods: The study was performed over 3 years, 1998-2000. Seventy-six patients with any colorectal lesion on colonoscopy were selected, and in all of them brush cytology and biopsy were done at the same time. The cytologic smears and biopsies were reviewed separately. The cytologic smears were categorized as negative, suspicious, suggestive or positive for malignancy. The results of cytology and biopsy were compared based on sensitivity and specificity. The gold standard for positive cases was the tissue specimen after surgery; negative cases were followed for at least 1 year. Cases with 1 year of disease-free survival were considered negative.

Results: Among 76 cases, 4 were excluded because of unsatisfactory cytologic smears. Of the remaining 72 cases, 31 were male and 41 female. The age range was 19-80 years. Cytology showed 23 positive and 49 negative cases (1 false positive and 3 false negative). Biopsy showed 24 positive and 48 negative cases (no false positives and 1 false negative). There were 47 negative cases, followed for at least 1 year, and after that we considered them definitively negative for malignancy. Sensitivity of cytology and biopsy was 88% and 96%; specificity was 98% and 100%, respectively. Combined use of brush cytology and biopsy had the highest sensitivity, 100%.

Conclusions: Brush cytology of the colon is a safe, fast and reliable method for the diagnosis of colorectal cancer. We recommend performing it in conjunction with biopsy. It is also reasonable to perform a repeat biopsy in patients with negative biopsy and positive cytology for a definitive diagnosis.