CARCINOMA OF THE COLON AND ULCERATIVE COLITIS

The risk of colorectal cancer in ulcerative colitis: a meta-analysis

BACKGROUND AND AIMS

Controversy surrounds the risk of colorectal cancer (CRC) in ulcerative colitis (UC). Many studies have investigated this risk and reported widely varying rates.

METHODS

A literature search using Medline with the explosion of references identified 194 studies. Of these, 116 met our inclusion criteria from which the number of patients and cancers detected could be extracted. Overall pooled estimates, with 95% confidence intervals (CI), of cancer prevalence and incidence were obtained using a random effects model on either the log odds or log incidence scale, as appropriate.

RESULTS

The overall prevalence of CRC in any UC patient, based on 116 studies, was estimated to be 3.7% (95% CI 3.2-4.2%). Of the 116 studies, 41 reported colitis duration. From these the overall incidence rate was 3/1000 person years duration (pyd), (95% CI 2/1000 to 4/1000). The overall incidence rate for any child was 6/1000 pyd (95% CI 3/1000 to 13/1000). Of the 41 studies, 19 reported results stratified into 10 year intervals of disease duration. For the first 10 years the incidence rate was 2/1000 pyd (95% CI 1/1000 to 2/1000), for the second decade the incidence rate was estimated to be 7/1000 pyd (95% CI 4/1000 to 12/1000), and in the third decade the incidence rate was 12/1000 pyd (95% CI 7/1000 to 19/1000). These incidence rates corresponded to cumulative probabilities of 2% by 10 years, 8% by 20 years, and 18% by 30 years. The worldwide cancer incidence rates varied geographically, being 5/1000 pyd in the USA, 4/1000 pyd in the UK, and 2/1000 pyd in Scandinavia and other countries. Over time the cancer risk has increased since 1955 but this finding was not significant (p=0.8).

CONCLUSIONS

Using new meta-analysis techniques we determined the risk of CRC in UC by decade of disease and defined the risk in pancolitics and children. We found a non-significant increase in risk over time and estimated how risk varies with geography.

Cancer in the excluded rectum following surgery for inflammatory bowel disease

The procedure of choice in the emergency surgical management of ulcerative colitis and Crohn's colitis is often subtotal colectomy and ileostomy. Further surgery of the retained rectum may be delayed, sometimes for many years. The risk of malignant change in ulcerative colitis is well documented; the cancer risk seems to be much less in Crohn's disease. Five cases are reported where carcinoma developed in the out-of-circuit rectal stump after subtotal colectomy, three cases of ulcerative colitis, and two of Crohn's disease. The importance of regular surveillance or removal of an excluded rectum is emphasized.

Survival with carcinoma arising in mucosal ulcerative colitis

Adenocarcinoma of the colon is a well-recognized complication of total chronic ulcerative colitis. The incidence increases with time, and the carcinoma arising in chronic ulcerative colitis has developed a bad clinical reputation in terms of aggressive behavior. The survival statistics of patients with cancer arising in chronic ulcerative colitis are compared with statistics for a group of noncolitic patients with equivalent clinicopathologic staging treated at the same institution. When grouped by extended Duke's classification and compared with carcinoma arising without ulcerative colitis, there was no statistical difference in survival rates. The overall results are worse because of a higher percentage of patients with incurable disease at the time of operation. With improved surveillance and methods of detecting premalignant changes, the necessity for prophylactic proctocolectomy should decline.

Radiological findings in carcinoma of the colon complicating chronic ulcerative colitis

Images