Similarity of colorectal cancer in Crohn's disease and ulcerative colitis: implications for carcinogenesis and prevention

Conversion of human colonic adenoma cells to adenocarcinoma cells through inflammation in nude mice

The roles of inflammation in the malignant progression of tumors during multistep carcinogenesis have been much discussed but remain to be elucidated. To determine the direct contribution of inflammation to colon carcinogenesis, we established a new model of progression of human colonic adenoma cells using a nude mouse; the progression is accelerated by coimplantation of a plastic plate. The FPCK-1-1 cell line, derived from a colonic polyp in a patient with familial adenomatous polyposis, is nontumorigenic when injected subcutaneously into nude mice in a cell suspension of up to 5 x 106 cells per mouse. However implantation of 1 x 10(5) FPCK-1-1 cells attached to a plastic plate induced first acute and then chronic inflammation, and formed progressively growing tumors that were histologically determined as moderately differentiated adenocarcinoma in 65% of mice. Moreover cell lines established from the growing tumors were found to be tumorigenic when injected into mice even without a plastic plate. The tumor arising from the adenoma cells implanted attached to a plastic plate was surrounded by highly proliferating fibrous stroma. This fibrous tissue was considered essential for malignant progression, rather than for attachment to the plastic plate substrate, because the tumors were formed after injection of FPCK-1-1 cells into the fibrous tissue from which the plastic plate had been removed before the cell injection. The conditioned medium (CM) obtained from the fibroblasts derived from a plastic plate-associated stromal tissue was found to contain factors that stimulated growth of FPCK-1-1 cells, but not of the derivative progressor cell lines. The factor was stable to heating and neuraminidase treatment, but labile to trypsin treatment. The main growth-potentiating activity was contained in the fraction larger than 100 kDa. In contrast, the activity to promote FPCK-1-1 cell growth was not present in the CM of subcutaneous fibroblasts from untreated nude mice or the fibroblast cell lines C3H10T 1/2 and NIH3T3. These results demonstrated that inflammation-associated stroma promoted the conversion of colonic adenoma cells to adenocarcinoma cells.

Psychosocial aspects of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) are known as inflammatory bowel disease (IBD), chronic and potentially disabling diseases, affecting about 90 to 300 per 100,000 people in the general population. Although significant gains have been made in our understanding of these diseases, particularly with respect to pathophysiology and treatment, its etiology is still unknown. IBD is a significant disease that can severely impact one's psychological and social well-being. This article reviews the literature on the psychosocial aspects of IBD. We also address the importance of conceptualizing IBD from a biopsychosocial perspective, considering psychosocial factors along with disease activity. The biopsychosocial approach offers a broadened perspective that reflects the many factors that may contribute to the expression and maintenance of IBD symptoms. Issues of concerns for patients with IBD are also discussed. Finally, we highlight the importance of establishing a collaborative therapeutic relationship between patients and their physicians, facilitating open and honest discussions acknowledging patients' fears and concerns. In doing so, much of these IBD-related issues of concerns may be ameliorated, potentially improving one's coping abilities, and lead to an improved quality of life for individuals with inflammatory bowel disease.

Hyperplastic-like mucosal change in Crohn's disease: an unusual form of dysplasia?

Patients with Crohn's disease are at increased risk of developing intestinal adenocarcinoma. Dysplasia is both a marker and a precursor of adenocarcinoma in this setting. In a review of our cases of Crohn's-related adenocarcinoma, we noted a peculiar hyperplastic-like mucosal change (HPC) in mucosa both adjacent to and distant from the adenocarcinoma in some cases. However, the significance of this change is unknown. We evaluated 30 cases of Crohn's-related adenocarcinoma and 30 age- and site-matched resection specimens with Crohn's disease without adenocarcinoma to determine the prevalence of this mucosal alteration in these groups. HPC was recognized by a diffuse expanse of flat mucosa with an architecture resembling that seen in colorectal hyperplastic polyps and composed of cells with cytologically bland basal nuclei and apical cytoplasmic mucin distention. The relationship of the HPC to the adenocarcinoma was noted in the Crohn's-related adenocarcinoma cases. An immunohistochemical stain for p53 (antibody DO7) was performed on all cases with HPC in both groups. HPC was identified in 10 of 30 (33%) cases of Crohn's-related adenocarcinoma compared with 3 of 30 (10%) cases in the control group (P = .03). In the 10 cases of Crohn's-related adenocarcinoma with HPC, this alteration was found adjacent to the adenocarcinoma in 3 cases, distant to the adenocarcinoma in 5 cases, and both adjacent to and distal from the adenocarcinoma in 2 cases. In two specimens, HPC was seen immediately adjacent to adenocarcinoma in the absence of adjacent dysplasia. p53 immunoreactivity was noted in HPC in 5 of 10 (50%) Crohn's-related adenocarcinomas. In contrast, p53 immunoreactivity was not seen in HPC in the three control cases with this mucosal alteration. In conclusion, HPC is found significantly more commonly in mucosa both adjacent to and distant from Crohn's-related adenocarcinoma when compared with age- and site-matched controls. In addition, p53 immunoreactivity is more commonly seen in HPC in cases of Crohn's-related adenocarcinoma compared with controls. These data suggest that this mucosal alteration may, in some cases, represent an unusual form of dysplasia in this setting.

Adenocarcinoma of the rectum with various grades of atypia in association with Crohn's disease: a case report and immunohistochemistry of p53 and Ki-67

A case of adenocarcinoma of the rectum in a 41-year-old woman, in association with Crohn's disease is presented. The patient had suffered diarrhea and constipation, and Crohn's disease was suspected. Although the endoscopy did not reveal the presence of any tumors, biopsy specimens demonstrated adenocarcinoma. A Miles' operation was performed. The adenocarcinoma was composed of various grades of atypia and had invaded the non-peritonealized perirectal tissues. The infiltration of lymphocytes and plasma cells was moderate at the perimeter of the carcinoma and mild in the distant regions. Epithelioid cell granulomas were found. The p53 labeling index (LI) increased with the grade of atypia over the entire length of the carcinomatous gland. In carcinomas with high grade atypia, the p53 LI was high in both the upper and the lower halves of the gland. In carcinomas with low or moderate grade atypia however, the p53 LI was high in the lower half and low in the upper half of the gland. The Ki-67 LI over the entire gland was higher in carcinomas with high grade atypia than in carcinomas with low or moderate grade atypia.

Cyclooxygenase-2 and carcinogenesis

Numerous investigations have shown that COX-2 is a participant in the pathway of colon carcinogenesis, especially when mutation of the APC tumor suppressor is the initiating event. Moreover, it seems that the amount of COX-2 is important, since there is a correlation between its level of expression and the size of the tumors and their propensity to invade underlying tissue [40]. Inhibiting COX-2 at an early stage blocks the development of malignant tumors, causes pre-malignant tumors to regress and may improve the outcome once the cancer is completely established. This set of findings seems to link very strongly with the traditional observation that chronic inflammation is a precursor to a variety of types of cancer. By this formulation, inflammatory stimuli increase COX-2 and the downstream events that it induces promote tumor formation. All of these finding suggest that existing NSAIDs will be useful for the prophylaxis of colon cancer and polyps and we eagerly await clinical investigations that will generate guidelines that suggest those individuals that are the most appropriate recipients for such therapy. Although this field has progressed rapidly in the last few years, many important questions remain.

Malignant neoplasms subsequent to treatment of inflammatory bowel disease with 6-mercaptopurine

OBJECTIVE

Most complications of 6-mercaptopurine (6MP) used in the treatment of inflammatory bowel disease (IBD) occur early, whereas neoplasms occur late in the course. Concern persists that the risk is increased when 6MP is used. We report our experience with malignant tumors developing over 27 yr of treating IBD patients with 6MP.

METHODS

A total of 591 patients with IBD treated with 6MP between 1969 and 1997 were followed or traced until present to identify all malignant tumors and blood dyscrasias that had developed to determine the type, distribution, and duration of the IBD, the dose and duration of 6MP therapy, the concurrent versus previous use of 6MP, the incidence and probable relationship of 6MP to specific neoplasms, and whether the 6MP had been effective in treatment.

RESULTS

A total of 550 patients (93%) fulfilled the criteria for follow-up; these included 380 with Crohn's disease (CD) and 170 with ulcerative colitis (UC). Twenty-five patients had developed neoplasms (16 of 380 CD and nine of 170 UC) (p = 0.66). In half of the cases, the goal of therapy had been achieved with 6MP. In 10 patients, the neoplasm was diagnosed while the patients were taking 6MP (40%) and in 15, many years after the 6MP had been terminated (60%). The incidence of neoplasms (25 of 550) was 2.7/1000 patient-years of follow-up. The most common neoplasms were found in the bowel (eight of 550, 1.6%; five CD, and three UC), and breast (three, 0.5%; two CD, and one UC). Non-Hodgkins lymphomas occurred in two patients with CD; one was cerebral and the other abdominal. One patient with CD developed leukemia. The duration of 6MP therapy ranged from 5 months to 22 yr, with a mean of 5 yr. The dose of 6MP ranged from a quarter of a tablet/day (12.5 mg) to 100 mg/day, with the majority in a range from 50 to 75 mg/day.

CONCLUSION

In no instance could a neoplasm be attributed to the use of 6MP. The incidence of colon cancer is not greater than that with long standing colitis. Suspicion of a relationship between 6MP and leukemia/lymphoma persists, but the incidence is low. This must be weighed against the improved quality of life due to 6MP for patients with IBD.

Case report: adenocarcinoma arising in a Crohn's stricture of the jejunum

Patients with Crohn's disease affecting the small intestine appear to have an increased risk of developing adenocarcinoma. However, it remains an uncommon complication of an uncommon disease. The diagnosis is difficult to make both pre- and intra-operatively, and is most commonly made postoperatively on histopathology. Hence, at laparotomy, consideration should be given to performing a frozen section on all small bowel strictures due to Crohn's disease to define the presence of dysplasia or cancer. This will assist the surgeon in deciding whether to perform a stricturoplasty or a resection.

Rectal cancer and inflammatory bowel disease: natural history and implications for radiation therapy

PURPOSE

There exists little information concerning the natural history of rectal cancer in patients with inflammatory bowel disease (IBD). In addition, the tolerance of pelvic irradiation in these patients is unknown. We analyzed the largest series of patients with IBD and rectal cancer in order to determine the natural history of the disease as well as the effect and tolerance of pelvic irradiation.

METHODS AND MATERIALS

A retrospective analysis of 47 patients with IBD and rectal cancer treated over a 34-year period (1960-1994) was performed. Thirty-five patients had ulcerative colitis and 12 patients had Crohn's disease. There were 31 male patients and 16 female patients. The stage (AJC) distribution was as follows: stage 0 in 5 patients, stage I in 13 patients, stage II in 7 patients, stage III in 13 patients, and stage IV in 9 patients. Surgical resection was performed in 44 patients. In two of these patients, preoperative pelvic irradiation was given followed by surgery. Twenty of these patients underwent postoperative adjuvant therapy (12 were treated with chemotherapy and pelvic irradiation and 8 with chemotherapy alone). Three patients were found to have unresectable disease and were treated with chemotherapy alone (2 patients) or chemotherapy and radiation therapy (RT) (1 patient). Radiation complications were graded using the RTOG acute and late effects scoring criteria. Follow-up ranged from 4 to 250 months (median 24 months).

RESULTS

The 5-year actuarial results revealed an overall survival (OS) of 42%, a disease-free survival (DFS) of 43%, a pelvic control rate (PC) of 67% and a freedom from distant failure (FFDF) of 47%. DFS decreased with increasing T stage with a 5-year rate of 86% for patients with Tis-T2 disease compared to 10% for patients with T3-T4 disease (p < 0.0001). The presence of lymph node metastases also resulted in a decrease in DFS with a 5-year rate of 67% for patients with NO disease compared to 0% for patients with N1-N3 disease (p < 0.0001). DFS decreased with increasing histopathologic grade with 5-year DFS rates of 71%, 52%, and 24% for grades 1, 2, and 3 respectively (p = 0.03). The T and N stages showed a statistically significant effect on pelvic control, with 5-year PC rates of 60% for Tis-2 versus 26% for T3-4 (p = 0.002) and 79% for NO versus 51% for N1-3 (p = 0.007). The histopathologic grade of the tumor did not significantly affect pelvic control. An analysis of high-risk patients (30) with T3-T4 or N1-N3 disease revealed at 5 years an OS of 9%, a DFS of 10%, a PC rate of 26%, and FFDF of 20%. In this subset of patients, there was a trend toward improved pelvic control in patients receiving RT (14 patients) with a 5-year PC of 60% compared to a rate of 23% for those patients not irradiated (16 patients). Acute complications (grade 3 or >) were noted in three patients (20%) receiving pelvic irradiation +/- chemotherapy and these included two cases of grade 3 skin reactions and one case of grade 4 gastrointestinal toxicity. Two patients (13%) developed small bowel obstruction at 2 and 4 months, respectively, postirradiation which were managed conservatively. There were no long-term complications in patients irradiated.

CONCLUSION

Treatment results are comparable to those historically reported for non-IBD-related rectal cancer although the subset of high-risk patients appeared to have a poorer outcome. In light of this finding and the ability of these patients to tolerate chemotherapy and pelvic irradiation, aggressive adjuvant therapy should be given to IBD-associated rectal cancer patients with high-risk features.

Cancer risk in patients with inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) are at increased risk for developing cancer of the gastrointestinal tract, particularly colorectal cancer. Because of the relative rarity of IBD in the general population, it has been difficult to quantify this risk. Efforts to reduce the risk have included both prophylactic surgery and endoscopic screening programs. Because of the potential impact on quality of life and life expectancy, the optimal strategy for reducing this risk has not been defined. This article reviews the current literature relating to the risk of cancer for patients with IBD and methods to reduce this risk.

Intestinal adenocarcinoma in Crohn's disease: a report of 30 cases with a focus on coexisting dysplasia

There are relatively few reports that detail the types of intestinal adenocarcinoma complicating Crohn's disease and examine associated epithelial dysplasia. We determined the prevalence, grade, and type of dysplasia found adjacent to and distant from Crohn's-related adenocarcinomas. Thirty cases of resected Crohn's-related adenocarcinoma were reviewed, and histologic type, degree of differentiation, TNM stage, and the presence or absence, grade, and location of dysplasia were recorded. Most of the patients were male (70%). The median ages at diagnosis of Crohn's disease and adenocarcinoma were 34 and 49 years, respectively. The extent of Crohn's disease included ileocolitis in 21 patients, only colonic disease in six, and only small bowel disease in three. In most cases (67%), carcinoma was found incidentally at surgery. All carcinomas arose in areas involved by Crohn's disease. Eight (27%) adenocarcinomas arose in the small bowel, and 22 (73%) arose in the colon, including two in out-of-circuit rectums. Most carcinomas (63%) were poorly differentiated. Dysplasia was found adjacent to the carcinoma in 26 (87%) cases. Of the colorectal carcinomas, 19 (86%) had adjacent dysplasia, and nine (41%) had distant dysplasia. In conclusion, most cases of Crohn's-related intestinal adenocarcinoma have dysplasia in adjacent mucosa, and 41% of those arising in the colorectum have distant dysplasia, supporting a dysplasia-carcinoma sequence in Crohn's disease.

Inflammatory cell-mediated tumour progression and minisatellite mutation correlate with the decrease of antioxidative enzymes in murine fibrosarcoma cells

We isolated six clones of weakly tumorigenic fibrosarcoma (QR) from the tumorigenic clone BMT-11 cl-9. The QR clones were unable to grow in normal C57BL/6 mice when injected s.c. (1x10(5) cells). However, they formed aggressive tumours upon co-implantation with a 'foreign body', i.e. a gelatin sponge, and the rate of tumour take ranged from 8% to 58% among QR clones. The enhanced tumorigenicity was due to host cell-mediated reaction to the gelatin sponge (inflammation). Immunoblot analysis and enzyme activity assay revealed a significant inverse correlation between the frequencies of tumour formation by QR clones and the levels of manganese superoxide dismutase (Mn-SOD, P<0.005) and glutathione peroxidase (GPchi, P<0.01) in the respective tumour clones. Electron spin resonance (ESR) revealed that superoxide-scavenging ability of cell lysates of the QR clone with high level of Mn-SOD was significantly higher than that with low level of the antioxidative enzyme in the presence of potassium cyanide, an inhibitor for copper-zinc superoxide dismutase (CuZn-SOD) (P<0.001). Minisatellite mutation (MSM) induced by the inflammatory cells in tumour cells were investigated by DNA fingerprint analysis after QR clones had been co-cultured with gelatin-sponge-reactive cells. The MSM rate was significantly higher in the subclones with low levels of Mn-SOD and GPchi (P<0.05) than in the subclones with high levels of both enzymes. The MSM of the subclones with low levels of both enzymes was inhibited in the presence of mannitol, a hydroxyl radical scavenger. The content of 8-hydroxydeoxyguanosine (8-OHdG) by which the cellular DNA damage caused by active oxygen species can be assessed was significantly low in the tumours arising from the QR clone with high levels of Mn-SOD and GPchi even if the clone had been co-implanted with gelatin sponge, compared with the arising tumour from the QR clone with low levels of those antioxidative enzymes (P<0.001). In contrast, CuZn-SOD and catalase levels in the six QR clones did not have any correlation with tumour progression parameters. These results suggest that tumour progression is accelerated by inflammation-induced active oxygen species particularly accompanied with declined levels of intracellular antioxidative enzymes in tumour cells.

Inhibition by platelet-activating factor of Src- and hepatocyte growth factor-dependent invasiveness of intestinal and kidney epithelial cells. Phosphatidylinositol 3'-kinase is a critical mediator of tumor invasion

This study was designed to characterize platelet-activating factor receptor (PAF-R) expression and function in normal and cancerous human colonic epithelial cells. PAF-R gene transcripts were analyzed by reverse transcription-polymerase chain reaction and Southern blot, using three sets of primers corresponding either to the coding region of the human PAF-R sequence (polymerase chain reaction product: 682 base pairs (bp)) or to the leukocyte- and tissue-type transcripts of 166 and 252 bp, respectively. An elongated splice variant was identified in the 5'-untranslated region of the tissue-type PAF-R transcript (334 bp) in colonic epithelial crypts and tumors. In human colonic PCmsrc cells transformed by c-src oncogene, the hepatocyte growth factor (HGF)-dependent invasiveness of collagen gels was abolished by 0.1 microM PAF and restored by the PAF-R antagonists WEB2086 and SR27417. PAF blocked HGF-induced tyrosine phosphorylation of p125 focal adhesion kinase. The phosphatidylinositol 3'-kinase (PI3'-K) inhibitors wortmannin and LY294002 totally blocked the HGF-induced invasion. Similar effects were observed in ts-srcMDCK kidney epithelial cells transformed by a v-Src temperature-sensitive mutant: (i) PAF and wortmannin exerted additive inhibitory effects on Src-induced invasion and (ii) activated and dominant negative forms of p110alpha PI3'-K, respectively, amplified and abrogated the Src- and HGF-dependent invasiveness of parental and ts-srcMDCK cells. We also provided the first evidence for the contribution of rapamycin-insensitive, pertussis toxin-dependent G-protein pathways to the integration of the signals emerging from activated Met and PAF receptors. These results indicate that PI3'-K is a critical transducer of invasiveness and strongly suggest that PAF exerts a negative control on invasion by inhibiting this signaling pathway. A possible beneficial role of PAF analogs on tumor invasion is therefore proposed.

Colorectal adenocarcinoma in Crohn's disease: a retrospective histologic study

PURPOSE

The aim of this study was to review all histopathologic sections from surgical specimens with inflammatory bowel disease and colorectal carcinoma filed at this hospital between 1951 and 1996.

METHOD

A total of 40 surgical (n = 39) or autopsy (n = 1) colon or colorectal specimens were reviewed. Internationally accepted histologic criteria were strictly applied to differentiate Crohn's disease (CD), ulcerative colitis (UC), and indeterminate colitis (IC).

RESULTS

Of the 40 specimens with inflammatory bowel disease and carcinoma, 22 (55 percent) had CD, 16 (40 percent) had UC, and the remaining 2 (5 percent) had IC. Males accounted for 72.7 percent or 16 of the 22 patients with colorectal carcinoma in CD and for 68.7 percent or 11 of the 16 patients with carcinoma in UC. Both patients with IC and carcinoma were males. The median age of patients at diagnosis was as follows: CD, 20 (range, 7-68) years; UC, 23 (range, 5-21) years. In IC, the age was 61 and 81 years, respectively. The median disease duration (before detection of colorectal cancer) was as follows: CD, 18.5 (range, 1-45) years; UC, 19 (range, 6-38) years. For cases with IC, it was 13 and 19 years, respectively. Median age of patients at cancer diagnosis was as follows: CD, 48 (range, 21-78) years; UC, 49 (range, 21-81) years. Ages at cancer diagnosis in IC were 68 and 81 years. Colorectal carcinoma tend to develop among relatively young patients with CD and UC. Mucinous adenocarcinomas accounted for approximately one-third of the carcinomas affecting CD. Thirty percent of old specimens (before the end of 1982) had in fact carcinoma complicating CD and not UC (the latter being the diagnosis appearing in old pathologic reports). During a time lapse of 38 years (i.e., between 1951 and 1989), only 11 cases of colorectal CD with carcinoma (i.e., 0.2 cases/year) were found, but as many as 11 during the past 6.5 years (i.e., 1.7 cases/year) have been diagnosed. Only 42.3 percent (11/26) of cases with colorectal inflammatory bowel disease and carcinoma operated on between 1951 and the end of 1989 had Crohn's colitis but as many as 78.6 percent (11/14) of those operated on between 1990 and May 1996 had Crohn's colitis. Review of the literature indicated that 64.8 percent or 191 of the 295 cases of colorectal carcinomas in CD so far reported occurred in the past 6.5 years. It would seem as if the risk of colorectal carcinoma in Crohn's colitis has increased in later years.

CONCLUSIONS

1) Reports on cancer frequency in UC based on old histopathologic records should be subjected to critical histologic re-evaluation; 2) carcinoma in Crohn's colitis has increased at this hospital, particularly since 1990; 3) the surveillance program strategy used in patients with long-standing UC at this hospital should also embrace patients with Crohn's colitis.

Evidence against flat dysplasia as a regional field defect in small bowel adenocarcinoma associated with celiac sprue

OBJECTIVE

To determine whether diffuse flat dysplasia, akin to that seen with chronic ulcerative colitis, occurs as a mucosal field defect accompanying small bowel adenocarcinoma in patients with celiac sprue.

DESIGN

A pathologic investigation of archival tissue was undertaken.

MATERIAL AND METHODS

From the tissue archives at Mayo Clinic Rochester for the period from January 1978 to January 1993, resected sprue-associated adenocarcinomas with adequate adjacent mucosa for study were identified. On the basis of multiple strip biopsy specimens obtained at the tumor margins and within 4 cm distal and proximal to the tumor, histologic maps were created.

RESULTS

Among 94 patients with primary adenocarcinoma of the small bowel, 8 had a concurrent diagnosis of celiac sprue. Of these eight cases, six surgically resected specimens (five duodenal and one jejunal adenocarcinoma) were adequate for study. A thin rim of benign dysplasia was demonstrated at the tumor margin in three of the six specimens; however, contiguous fields of flat dysplasia were not present in any of these cases.

CONCLUSION

These data support focal dysplasia (for example, adenoma) rather than sheets of flat dysplasia as the premalignant lesion in sprue-associated small bowel adenocarcinoma. Blind endoscopic biopsies of small bowel mucosa are not justified for neoplasia surveillance in patients with celiac sprue.

Colorectal adenocarcinoma in Crohn's disease

OBJECTIVE

The authors' aim was to review the clinical features and estimate the long-term survival of patients with colorectal carcinoma complicating Crohn's disease.

SUMMARY BACKGROUND DATA

Recent studies have demonstrated a significantly increased risk of colorectal carcinoma in patients with Crohns disease.

METHODS

The authors reviewed retrospectively the medical records of 30 patients with Crohn's disease admitted to The Mount Sinai Hospital between 1960 and 1989 in whom colorectal adenocarcinoma developed. All patients were operated on and follow-up was complete for all patients to 10 years after operation, to the time of death, or to the closing date of the study in December 1989.

RESULTS

The 30 patients in the series had 33 colorectal adenocarcinomas; three patients (10%) presented with two synchronous cancers. The patients were relatively young (mean age, 53 years) and had long-standing Crohn's disease (duration >20 years in 87%). The 5-year actuarial survival was 44% for the overall series: 100% for stage A, 86% for stage B, 60% for stage C. All five patients with excluded bowel tumor died of large bowel cancer within 2.4 years; by contrast, the actuarial 5-year survival for patients with in-continuity tumors was 56%.

CONCLUSIONS

The incidence, characteristics, and prognosis of colorectal carcinoma complicating Crohn's disease are similar to the features of cancer in ulcerative colitis, including young age, multiple neoplasms, long duration of disease, and greater than a 50% 5-year survival rate (without excluded loops). These observations suggest the advisability of surveillance programs for Crohn's disease of the colon similar to those for ulcerative colitis of comparable duration and extent.

Is mucinous carcinoma of the colorectum a distinct genetic entity?

Mucinous carcinomas are defined on the basis of the amount of the mucus component in the tumour mass. Apart from this quantitative criterion, a number of clinicopathological parameters (such as localisation, prevalence in different countries and age groups, association with HNPCC and inflammatory processes) and genetic alterations (e.g. frequency of mutation in Ki-ras and p53 genes, level of MUC2 expression) differentiate these tumours from the non-mucinous ones. Since a different set of genetic lesions implies different inducing agents, these observations suggest that there may be a 'mucinous pathway of carcinogenesis'. Further identification of genetic changes characteristic of the mucinous phenotype will help to understand the aetiology of these tumours and possibly establish markers for detection of the high-risk group.

Premalignant changes in ulcerative colitis

Colitis-associated carcinoma is often associated with, or preceded by, noninvasive epithelial neoplastic changes termed dysplasia. Surveillance colonoscopy with biopsies looking for dysplasia is now standard practice in the management of the cancer problem in ulcerative colitis. However, this practice continues to have a number of limitations and problems that need to be understood by surgeons who may be referring such patients. A number of recent reports indicate that colitis associated carcinoma is predominantly left-sided and incorporation of this distribution in the surveillance methods merits consideration. The molecular and genetic abnormalities involved in the pathogenesis of colitis associated neoplasia are being actively investigated and may yield supplementary methods to better define individual patient risk.