Reviewed 16 Nov. 2005

General

Several randomized studies have now been published which show significant reduction in mortality from colorectal cancer in persons over 50 years of age who were screened by fecal occult blood testing. As yet, there is no national consensus on the exact timing of such screening, but until further data is available, it is recommended that screening of asymptomatic individuals between age 50 and 75 be carried out on an annual basis. Those who test positive should undergo an evaluation of the entire colon, either by colonoscopy or a combination of flexible sigmoidoscopy and double contrast barium enema. Recommendations for routine screening in British Columbia have been developed (see Guidelines & Protocols Advisory Committee) and approved by MSP.

Inflammatory Bowel Disease

Individuals with active chronic (8 years or more duration) ulcerative colitis and pancolonic Crohn's disease are at increased risk of colorectal cancer. Colonoscopy with biopsy is recommended every 1 to 3 years if biopsies for malignancy are negative or indefinite. More frequent (every 3-6 months) endoscopy is indicated if biopsies show low-grade dysplasia. If high-grade dysplasia is found, or low grade dysplasia is persistent in several studies, colectomy is recommended.

For disease limited to the left colon, surveillance is carried out as above, but begins later, after 12-15 years of disease.

Hereditary/ Genetic Syndromes

As many as 25% of colorectal cancers (CRC) occur in persons considered to be at increased risk. The majority of these cases are in those with a family history of CRC, but with no definable genetic syndrome. Both the number of relatives affected and their age at onset are important in estimating risk. Persons with a strong family history of CRC in close relatives should consider screening at age 40. If the family history is particularly strong, a decision to proceed with complete evaluation of the colon may be made.

1. Hereditary Non-polyposis Colon Cancer (HNPCC)

Up to 5% of CRC may be secondary to the hereditary non-polyposis cancer syndrome (HNPCC). There are some criteria, which, if present, suggest the presence of HNPCC. The Amsterdam criteria were the first clinical criteria developed to support the diagnosis of HNPCC. They are quite restrictive, but if present, the chance of HNPCC is quite high. The newer Bethesda criteria are less restrictive and accordingly more sensitive, but somewhat less specific.

Amsterdam criteria

1. At least three relatives with histologically verified colorectal cancer, including a first degree relative of the other two (patients with familial adenomatous polyposis [FAP] are excluded); AND
2. At least two successive generations affected; AND
3. In at least one of the above individuals, diagnosis of colorectal cancer prior to the age of 50 years.

Bethesda criteria:

1. Individuals with cancer in families that meet the Amsterdam criteria; OR
2. Individuals with two HNPCC-related cancers, including synchronous and metachronous colorectal cancers or associated extra-colonic cancers (endometrial, ovarian, gastric, hepatobiliary, small bowel or transitional cell cancer of the renal pelvis or ureter); OR
3. Individuals with colorectal cancer and a first degree relative with colorectal cancer and/or HNPCC-related extracolonic cancer and/or a colorectal adenoma. One of the cancers must have been diagnosed at age < 45 years and the adenoma at age < 40 years; OR
4. Individuals with colorectal cancer or endometrial cancer diagnosed at age < 45 years; OR
5. Individuals with right-sided colon cancer with an undifferentiated pattern (solid/cribriform) diagnosed at < 45 years; OR
6. Individuals with signet ring cell type colorectal cancer (> 50% signet ring cells) diagnosed at < 45 years; OR
7. Individuals with colorectal cancer diagnosed at < 40 years.

Persons in whom the HNPCC syndrome is suspected should be referred for genetic counselling, within the hereditary cancer program, if available. They should be offered an examination of the colon every 1-2 years commencing between age 20 and 30; and every year after age 40. These guidelines continue to undergo revision; discussion with a member of the GI Tumour Group or a genetic counsellor is encouraged.

2. Familial Adenomatous Polyposis and Gardner Syndromes

Adenomatous polyposis coli (familial adenomatous polyposis syndrome (FAP) and the Gardner syndrome) accounts for about 1% of CRC. Relatives of patients with this syndrome should be referred for genetic counselling. Gene carriers or indeterminate relatives should receive flexible sigmoidoscopy every 12 months beginning at puberty. Colectomy is recommended when polyposis is found, as the lifetime risk of colon cancer is 100% if the colon is not removed. Patients with FAP are also at increased risk of ampullary carcinoma and of duodenal and gastric polyps. Upper endoscopy with biopsy should be performed regularly.

Reference:

1. Muller A, Fissile R, Mismatch repair and the hereditary non-polyposis colorectal cancer syndrome (HNPCC). Cancer Investigation 20(1), 102-109, 2002