4501 Distribution of advanced and non advanced adenomatous neoplasia in average risk patients with a hemoccult positive stool compared to patients with an abnormal flexible sigmoidoscopy.

Abstract

The use of Hemoccult testing and flexible sigmoidoscopy(FS) is an accepted and common practice in screening for colorectal malignancies. A patient with a Hemoccult positive(H+) stool is usually referred directly to colonoscopy (CSP) in screening programs instead of receiving a FS. The goal of this study was to compare the distribution and histology of adenomatous polyps(AP) in patients with H+ stool to those who undergo CSP after an AP in found on FS. Methods: CSP, FS, and pathology reports were reviewed retrospectively on all patients with a H+ stool at Wilford Hall Medical Center (WHMC) and FS at WHMC and Brooke Army Medical Center from 12/95 to 5/99. Patients were excluded if they had documented personal history of hematochezia, anemia, colon cancer/polyps or family history of colorectal cancer. Any AP in the rectum, sigmoid, or descending colon to a distance of 60 cm or seen on FS was considered to be distal while all other AP were considered proximal. Advanced adenomatous polyps were defined as: (1) >10 mm in size or (2) villous histology or (3) high grade dysplasia/malignancy. Results: There were 115 colonoscopies performed on patients with H+ stool that met these criteria. 5291 FS were performed with 606(11.4%) revealing an AP. CSP reports were available for 550(90.8%) of these patients. Table 1 summarizes the two groups. Conclusions: The prevalence of distal AP was higher in patients with H+ stool compared to FS patients(33.9% vs 11.4%) as was advanced distal AP(20% vs. 2.5%). However the prevalence of proximal AP in patients with H+ stool was similar to that of FS patients(33.9% vs. 33.8%) as was the prevalence of advanced proximal AP(7.0% vs. 7.6%). This data suggests that the primary cause for a H+ stool with regards to colorectal cancer screening is the presence of distal adenomatous neoplasia, especially advanced neoplasia.