Narrow band imaging for the detection of neoplastic lesions of the colon

Upper and Lower Gastrointestinal Findings in PTEN Mutation-Positive Cowden Syndrome Patients Participating in an Active Surveillance Program

OBJECTIVES:

Cowden syndrome (CS), associated with germline PTEN mutations, is an autosomal-dominant disorder with increased frequencies of thyroid and breast cancers. Recent reports document the occurrence of gastrointestinal (GI) polyps and increased risk of colon cancer in PTEN mutation carriers. Studies to date, however, have not been based on mutation carriers undergoing active, systematic, routine-interval GI surveillance. Our objective is to document the upper and lower GI findings in CS patients undergoing such an active GI surveillance program.

METHODS:

In a 5-year period, 3,000 consecutive patients were referred to our high-risk GI cancer clinic for various reasons. Of these 3,000, 10 met full-blown clinical criteria for the diagnosis of CS. Individuals with identified PTEN mutations underwent annual upper and lower endoscopy surveillance programs using dual white light and narrow-band imaging. All biopsies including archived materials were reviewed by a single dedicated GI pathologist.

RESULTS:

Ten PTEN mutation carriers from different ethnic backgrounds were invited and all participated in the active GI surveillance program. Eight patients had colonic polyps, mostly hyperplastic (eight patients) and hamartomatous (five patients), but also adenomatous (three patients), ganglioneuromatous (three patients), and juvenile polyps (two patients). One patient (10%) had an early-onset rectal cancer (aged 44 years), which was null for PTEN expression on immunohistochemistry. All patients had gastric polyps and nine (90%) had duodenal polyps, mostly hyperplastic and hamartomatous. Additional three patients (30%) had adenomatous duodenal polyps.

CONCLUSIONS:

PTEN mutation–positive CS patients have a higher frequency of upper GI polyps than previously believed. They appear prone to develop adenomatous upper and lower tract dysplastic polyps and cancer. Thus, the polyps encountered during upper or lower endoscopy in these patients should not be automatically considered innocent hamartomas without malignant potential. Active surveillance programs in specialized centers should be considered in these patients.

Evaluating the vascularity of intestinal anastomoses--can narrow band imaging play a role?

A variety of factors are critical for the success of bowel anastomoses. The most crucial patient factor is adequate vascularity of the bowel ends which are to be anastomosed. Currently, intraoperative features such as healthy looking bleeding edges of the bowel are considered to be signs of adequate vascular supply. However, once the anastomosis is performed, external appearances may not be reliable. In order to improve evaluation of the bowel as well as the anastomosis, our group has adopted the routine use of post-anastomosis intraoperative colonoscopy. Intraoperative colonoscopy provides vital information regarding the integrity of the anastomosis (leak testing) and also visualizes the mucosa of the bowel. Narrow Band Imaging (NBI) is a novel real-time imaging technique which is an integral component of many modern colonoscopes. We hypothesize that NBI assessment of vascularity at the time of intestinal anastomosis can improve safety and reduce the risks of anastomotic complications following surgery.