Colonoscopic biopsy and cytology in the diagnosis of colon cancer.

Colonoscopy has revolutionalized the approach to the diagnosis and management of patients with colorectal neoplasia. When malignant-appearing lesions are visualized by colonoscopy, a variety of diagnostic techniques are currently available for the assessment of the nature of the lesion including biopsy, brush cytology, and lavage cytology. Comparison of results for biopsy alone with biopsy plus either or both cytologic techniques showed a positive yield of 60% for biopsy alone; 76% for biopsy and lavage; 89% for biopsy, brush, and lavage. When the cancers were divided into infiltrative and exophytic lesions the positive yield for biopsy alone was 33% for infiltrative, cancer, and 71% for exophytic cancer; for biopsy and lavage cytology, 44% for infiltrative cancer, and 94% for exophytic cancer; for biopsy and brush cytology, 78% for infiltrative, and 94% for exophytic cancer; and for biopsy, brush, and lavage cytology, 83% for infiltrative cancer, and 92% for exophytic cancer. The use of brush cytology improved the yield of tissue diagnosis considerably when added to the biopsy technique. Lavage cytology did not seem to increase significantly the diagnostic yield. The diagnostic yield of the various techniques was related not only to the specific combination of techniques used, but also to the gross tumor pattern.