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Genetics of Colorectal Cancer (PDQ®): Genetics - Health Professional Information [NCI] - Major Genetic Syndromes

Table 5. Extracolonic Tumor Risks in Familial Adenomatous Polyposis continued...

These three studies illustrate some of the problems encountered in the study of desmoid disease in FAP patients:

  • The definition of desmoid disease has been used inconsistently.
  • In some patients, desmoid tumors do not progress or are very slow growing and may not need therapy.
  • There is no consistent, systematic way to evaluate the response to therapy.
  • There is no single institution that will enroll enough patients to perform a randomized trial.

No randomized clinical trials using these agents have been performed and their use in clinical practice is based on anecdotal experience only.

Level of evidence: 4

Because of the high rates of morbidity and recurrence, in general, surgical resection is not recommended in the treatment of intra-abdominal desmoid tumors. However, some have advocated a role for surgery given the ineffectiveness of medical therapy, even when the potential hazards of surgery are considered, and recognizing that not all desmoids are resectable.[48] A recent review of one hospital's experience suggested that surgical outcomes with intra-abdominal desmoids may be better than previously believed.[48,49] Issues of subject selection are critical in evaluating surgical outcome data.[49] Abdominal wall desmoids can be treated with surgical resection, but the recurrence rate is high.

Stomach tumors

The most common FAP-related gastric polyps are fundic gland polyps (FGPs). FGPs are often diffuse and not amenable to endoscopic removal. The incidence of FGPs has been estimated to be as high as 60% in patients with FAP, compared with 0.8% to 1.9% in the general population.[16,18,50,51,52,53,54] These polyps consist of distorted fundic glands containing microcysts lined with fundic-type epithelial cells or foveolar mucous cells.[55,56]

The hyperplastic surface epithelium is, by definition, nonneoplastic. Accordingly, FGPs have not been considered precancerous; in Western FAP patients the risk of stomach cancer is minimally increased, if at all. However, case reports of stomach cancer appearing to arise from FGPs have led to a reexamination of this issue.[18,57] In one FAP series, focal dysplasia was evident in the surface epithelium of FGPs in 25% of patients versus 1% of sporadic FGPs.[56] In a prospective study of patients with FAP undergoing surveillance with esophagogastroduodenoscopy, FGPs were detected in 88% of the patients. Low-grade dysplasia was detected in 38% of these patients, whereas high-grade dysplasia was detected in 3% of these patients. In the author's view, if a polyp with high-grade dysplasia is identified, polypectomy can be considered with repeat endoscopic surveillance in 3 to 6 months. Consideration for treatment with daily proton-pump inhibitors also may be given.[58]

Complicating the issue of differential diagnosis, FGPs have been increasingly recognized in non-FAP patients consuming proton pump inhibitors (PPIs).[56,59] FGPs in this setting commonly show a "PPI effect" consisting of congestion of secretory granules in parietal cells, leading to irregular bulging of individual cells into the lumen of glands. To the trained eye, the presence of dysplasia and the concomitant absence of a characteristic PPI effect can be considered highly suggestive of the presence of underlying FAP. The number of FGPs tends to be greater in FAP than that seen in patients consuming PPIs, although there is some overlap.


WebMD Public Information from the National Cancer Institute

Last Updated: February 25, 2014
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