Management of LGD

The optimal management of UC patients with LGD is controversial. Some experts recommend colectomy, because a high probability of finding an occult cancer in the colec-tomy specimen from these patients has been reported. However, the retrospective studies upon which these recommendations are based used a variable number of biop-

TABLE 83-1. Time Intervals between Surveillance Colonoscopies Assuming Adequate Sampling Has Been Achieved

Histology Interval between Colonoscopies

Negative for dysplasia 3 years Indefinite for dysplasia 1 year LGD 6 to 12 months

HGD Colectomy; for those who refuse colectomy then colonoscopy every 3 to 6 months

HGD = high grade dysplasia; LGD = low grade dyplasia.

sies (average 13 to 30 biopsies per 100 cm colon) obtained at inconsistent colonoscopic intervals varying from 1 month to 5 years. Thus the finding of occult cancers in these studies is not surprising because insufficient numbers of biopsies were taken to make the correct histologic diagnosis.

Although colectomy may be the least costly method for managing patients with LGD, many patients are reluctant to undergo this surgery. Patients who have had UC for 20 years, which is the average duration of disease prior to the development of dysplasia, often have minimal or no symptoms, and it can be difficult to convince them that a colec-tomy will benefit them. An informed discussion of the risks and benefits of colectomy for LGD requires an understanding of its natural history. Important questions about the biology of LGD include the following:

1. Do all patients with LGD develop cancer?

2. If so, over what time frame?

3. Does LGD ever regress?

4. Is HGD always an intermediate step between LGD and cancer?

5. Can it be detected with confidence?

6. Are there patient characteristics that predict who will progress to cancer?

We performed a prospective evaluation of the natural history of LGD in 18 UC patients. The preliminary results suggest that only one-third of these LGD patients will progress in the short term, and those who do progress usually do so within 18 months of the diagnosis of LGD. With our protocol of 4 quadrant biopsies every 10 cm and follow-up intervals occurring at least annually, none of the 18 LGD patients developed cancer while under surveillance. Six patients who progressed in the study developed HGD and underwent colectomy; none had an unsuspected carcinoma in their colectomy specimen. Characteristics of those who were more likely to progress to HGD included (1) patients with three or more biopsies with LGD per colonoscopy and (2) younger patients. Two-thirds of LGD patients did not progress, but rather continue to have LGD or downgraded to indefinite or negative for dysplasia during an average follow-up of 3 years. Because of these data, we do not routinely recommend colectomy for UC patients with LGD, but rather follow them endoscopically every 6 to 12 months, taking an adequate number of biopsies so that HGD or cancer will be detected if it is present.

The surveillance protocol described above is time intensive, expensive, and requires collaborative commitment from the physician, the patient, and the pathologist; moreover, one cannot absolutely guarantee that the patient will not develop cancer. If the gastroenterologist takes fewer biopsies, does not have access to a good GI pathologist, or if the patient is unwilling to adhere to a strict surveillance protocol, then colectomy is probably the safest plan of action in the setting of LGD found in flat mucosa. For dys-plasia found in a polyp, see guidelines below.

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