Surveillance Indications

SR Brown, Northern Hospital, Sheffield

Powerpoint File

Unlike screening, which is carried out on an asymptomatic population, surveillance implies a pre-existing condition enhancing malignant potential. There are several such conditions where colonoscopy is the optimal surveillance tool. Guidelines for the appropriate indications and the timing of the colonosocopy have been published by the British Society of Gastroenterology (paradoxically under the title ‘Guidelines for Colorectal Cancer Screening’) (1).

Surveillance for metachronous cancers

There is no evidence that colonoscopic follow up has a significant impact on survival after surgery for colorectal cancer. Nevertheless almost all would recommend surveillance based on the fact that it does produce a yield of treatable tumours. Interestingly, colonoscopic follow up is recommended in all treatment arms of the current FACS trial (2). We may therefore never know whether such follow-up does indeed improve survival.

Acromegaly

The raised serum growth factors and the prolonged survival now seen in acromegalics have highlighted the increase prevalence of colorectal adenomas and cancer in this group. Evidence is strong enough (and the population small enough) to warrant surveillance.

Ureterosigmoidoscopy

The malignant potential of any urinary diversion that mixes urine and stool is well known. Such patients are rare since the development of alternative diversion techniques, but the significant enhanced neoplastic potential around the anastomosis warrants surveillance.

Hereditary Bowel Cancer

Although environment plays an important role in colorectal carcinogenesis, there is a distinct hereditary component. Several epidemiological studies have indicated that a first-degree relative of a patient with colorectal cancer has a 3-5 fold increased risk of developing bowel cancer compared with the general population. This risk is increased further if there is more than 1 affected relative or the affected relative developed cancer at an early age. Surveillance recommendations are difficult to individualise as the risk of the colonoscopy may in many circumstances outweigh the risk of neoplasia.

In some extreme examples of hereditary predisposition (e.g. HNPCC, FAP, Peutz-Jegher syndrome) the risks are substantial and easier to quantify, making screening recommendations easier to formulate. Nevertheless controversies still exist.

Inflammatory Bowel Disease

The premalignant potential of long term UC is well known and relates to the extent and duration of the disease. Many clinicians practice surveillance in the hope of detecting dysplasia or cancer at a surgically curable stage. However, debate continues over the efficacy and cost effectiveness of surveillance programmes. These factors may be enhanced by the recent evidence for chromoscopy and targeted biopsy (3,4).

Polyp surveillance

Around one third of the population will develop an adenoma by the age of 60. This risk group therefore comprises the potentially the largest surveillance group. Because of finite resources it is important to rationalise surveillance based on risk-benefit analysis. The risk of malignancy is proportional to the number and size of polyps found.

When creating guidelines and recommendations for a national population, it is important to weigh up not only the potential risk-benefit but also the finite resources available. Although the evidence with regard to the risk-benefit balance is strong for many of these conditions, it is sometimes difficult to be pragmatic when faced with an anxious individual in clinic who does not meet the guidelines for surveillance.

References

1. Guidelines for colorectal cancer screening in high risk groups. Gut 2002;0(suppl V):v1-v28.

2. FACS Trial. A randomised controlled trial to assess the cost-effectiveness of intensive verses no scheduled follow-up in patients who have undergone resection for colorectal cancer with curative intent. Website http://www.facs.soton.ac.uk.

3. Rutter MD, Saunders BP, Schofield G, Forbes A Price AB, Talbot IC. Pancolonic indigo carmine dye spraying for the detection of dysplasia in ulcerative colitis. Gut 2004;53:256-60.