What can experimental colorectal cancer tell us about colorectal cancer in man?

Hepatocellular and gastric carcinoma associated with familial polyposis coli

A case of familial polyposis coli in association with hepatocellular and gastric carcinoma is reported. No similar case has ever been documented in the world literature. This may be surprising as it is well known that familial polyposis has a potent oncogenicity not only in the colon but also in extracolonic organs.

Relationship between duodenal bile acids and colorectal neoplasia

To investigate a possible relationship between bile acids and colorectal neoplasia duodenal bile acids were analysed in 50 patients with colorectal adenomas and 14 with carcinoma. Using gas liquid and high performance liquid chromatography a small, but significant increase in the proportion of chenodeoxycholic acid was found in the bile of adenoma patients compared with controls (mean % +/- SD 31.0 +/- 10.8, 26.4 +/- 8.3, p = 0.01). The difference in the proportions of chenodeoxycholic acid correlated with increasing malignant potential of the adenomas as determined by increasing size, histological type, degree of dysplasia and number present. In carcinoma patients an increase in the proportion of chenodeoxycholic acid was also observed compared with controls (mean % +/- SD, 47.2 +/- 9.6, 28.0 +/- 4.5, p less than 0.01). The proportions of other bile acids in those with adenoma or carcinoma were normal.

Dysplasia of the colon after jejuno-ileal bypass

Colonoscopic biopsies were performed on 38 patients, 10-13 years after jejuno-ileal bypass. No significant dysplasia or premalignant change was seen in 371 biopsies. In one patient two tubulovillous adenomata were found in an otherwise normal colon, which is likely to be a chance finding. Although it will take another 10-20 years to establish whether jejuno-ileal bypass is associated with an increased risk of large bowel cancer in humans, there is at present no indication for regular colonoscopic surveillance.

Drug therapy of inflammatory bowel disease

Although the etiology of inflammatory bowel disease is unknown and specific therapy is unavailable, enough information on existing empiric agents is available to allow rational therapy. These agents include sulfasalazine, steroids, immunosuppressive drugs, metronidazole and cholestyramine. Sulfasalazine is a two-part molecule that depends on bacterial cleavage in the colon to deliver locally acting 5-aminosalicylate, whose mechanism of action may relate to inhibition of prostaglandin synthesis. The other half of the molecule, sulfapyridine, is responsible for most of the side effects of the drug. While the efficacy of sulfasalazine in the treatment and prevention of attacks of ulcerative colitis is well established, its use in Crohn's disease appears to be limited to patients with active colitis and ileo-colitis. Sulfasalazine is of major benefit in preventing relapses in patients with ulcerative colitis in remission. New formulations of 5-aminosalicylate may allow delivery of the apparently active moiety to the small bowel and colon without concomitant sulfapyridine toxicity. Corticosteroids are highly effective in acute attacks of ulcerative colitis and Crohn's ileitis and ileo-colitis; the mechanism of antiinflammatory action remains speculative. However, maintenance therapy with steroids is ineffective in preventing relapses or recurrent attacks of either ulcerative colitis or Crohn's disease. Steroid enemas allow topical administration to patients with distal colitis and proctitis with few systemic side effects. In children with growth failure associated with active Crohn's disease, amelioration by steroid therapy may actually restore normal growth. Immunosuppressive agents such as azathioprine and 6-mercaptopurine are of little value in active Crohn's disease when administered alone; however, in combination with other agents they may help diminish steroid dose, close fistulae and prevent relapse. Their mode of action likely depends on long-term cytostatic effects on immune effector cells. Concern for leukopenia and the development of late malignancy has limited their use to patients not responding to other therapies. Metronidazole, an antimicrobial agent that is effective against anaerobes, has recently been shown useful in Crohn's disease involving the colon and perianal area. Its mechanism of action is uncertain, but may be related to its antibacterial actions on anaerobes. Cholestyramine can be successfully used to control bile salt-induced diarrhea in Crohn's patients with terminal ileal resections. Effective drug therapy of inflammatory bowel disease is only part of a total program of management including reassurance, frequent explanation, well-timed use of surgery, and an understanding physician.

Upper gastrointestinal tract polyps in familial adenomatosis coli

Upper gastrointestinal tract polyps were sought prospectively using endoscopy and biopsy in 34 patients with familial adenomatosis coli belonging to 18 unrelated families. Gastric and/or duodenal polyps, usually small and multiple, occurred in 28 patients (82%). Histologically verified extracolonic adenomas were present in 19 patients (56%). Gastric adenomas, all in the antrum, and duodenal adenomas occurred in four (12%) and 16 (48%) patients, respectively. In one patient, a duodenal adenocarcinoma and a bile duct adenoma were also found, and one patient had an adenocarcinoma of the bile ducts. Multiple non-neoplastic polyps were found in 19 patients (56%), most often in the stomach and also in the duodenum in 12 patients; they co-existed often with adenomas. In addition, there were nine patients with ileal polyps, most of them showing lymphoid hyperplasia but also one with adenomas. It is suggested that familial adenomatosis affects the whole gastrointestinal tract, not only the colon and rectum as believed earlier. Although upper gastrointestinal tract adenomas are not as consistent and multiple as those in the colon, and probably do not require prophylactic surgery, regular lifelong endoscopic follow up is warranted because of obviously increased cancer risk.