Outcome, comorbidity, hospitalization and 30-day mortality after closure of acute perforations and postoperative anastomotic leaks by the over-the-scope clip (OTSC) in an unselected cohort of patients.

BACKGROUND: Acute gastrointestinal (GI) wall defects contain a high risk of morbidity and mortality and may be closed endoscopically by a full-thickness over-the-scope clip (OTSC). METHODS: Unselected consecutive patients presenting with acute non-surgical perforations or postoperative anastomotic leaks or perforations underwent attempted OTSC placement as primary closure method after interdisciplinary consensus in three tertiary referral centres. Their clinical data and intervention characteristics were evaluated in an intention to treat analysis during a 24-month period to assess closure rates, 30-day mortality, hospitalization and comorbidity. RESULTS: In total, 34 patients (16 females, 18 males, 69.5 years) were included with 22 non-surgical perforations and 12 postoperative anastomotic leaks or perforations. Definitive closure of the perforations and leaks was achieved in 26/34 patients (76.5 %). Successful closure of the GI wall defect resulted in a significantly shorter hospital stay (8 days, p = 0.03) and was significantly correlated with comorbidity (r = 0.56, p = 0.005). In the group with OTSC failure, hospitalization was 18 days and 6 of 8 patients (75 %) required immediate surgery. Three deaths occurred in the group with successful OTSC closure due to comorbidity, while one death in the OTSC failure group was related to a refractory perforation. Favourable indications and locations for a successful OTSC procedure were identified as PEG complications, endoscopic or postoperative leaks of stomach, colon or rectum, respectively. CONCLUSIONS: In unselected patients, OTSC was effective for closure of acute GI wall defects in more than 75 % of all patients. Clinical success and short hospitalization were best achieved in patients without comorbidity, but closure of the perforation or the anastomotic leak was found to be not the only parameter relevant for patient outcome and mortality.

["Giant" fibrovascular esophageal polyp]. / "Gigantischer" fibrovaskulärer Polyp des Ösophagus.

Fibrovascular polyps are rare mesenchymal tumors that arise mainly in the cricopharyngeal portion of the esophagus. They may protrude distally to become "giant" pedunculated lesions filling almost the entire esophageal lumen. Histologically they contain varying amounts of adipose, fibrous and vascular tissues and belong to spindle cell lipomas according to the classification of soft tissue tumors. Immediate resection of these benign lesions is warranted as they may be regurgitated and cause asphyxia. These lesions are usually treated by open surgery (left cervicotomy) or, less invasively, by peroral endoscopic surgery. Polyp removal by flexible endoscopy has been described but may be hazardous if its stalk is broad-based. In this report the case of a 73-year-old male with dysphagia is described in whom a "giant" fibrovascular polyp was diagnosed endoscopically and promptly removed surgically by the peroral route. At control endoscopy 14 months later, the asymptomatic patient was free of polyp recurrence.

[Segmental necrotizing colitis in a patient with E. coli O104:H4 infection]. / Segmentale nekrotisierende Kolitis bei einem Patienten mit EHEC-Infektion vom Typ O104:H4.

A 29-year-old man presented with abdominal cramps and bloody diarrhoea. Blood tests revealed elevated C-reactive protein (21.3 mg/dL; normal range 0.01 - 0. 82 mg/dL) and white blood cells (28200/µL, normal range 4000 - 10000/µL). Stool tests were negative for enteropathogenic bacteria and Clostridium difficile toxins A/B. Ultrasound and computed tomography showed massive swelling of the transverse colon and right colonic flexure. At endoscopy, circular necrosis of the mucosa was encountered in the proximal segments of the colon whereas distal parts of the organ showed patchy inflammation of minor severity. Extended stool testing identified Escherichia coli type O104:H4 as the causative microorganism. There was no evidence for haemolytic uraemic syndrome. Under conservative treatment the patient recovered clinically, serologically and endoscopically. At follow-up endoscopy, longitudinal ulcers and vital mucosa were present. In this case report the segmental pattern of mucosal necrosis in a patient with EHEC infection is noteworthy.

Novel findings on the metabolic effects of the low glycaemic carbohydrate isomaltulose (Palatinose).

The slow digestible disaccharide isomaltulose (iso; Palatinose) is available as novel functional carbohydrate ingredient for manufacturing of low glycaemic foods and beverages. Although basically characterised, various information on physiological effects of iso are still lacking. Thus, the objective of the present study was to expand scientific knowledge of physiological characteristics of iso by a set of three human intervention trials. Using an ileostomy model, iso was found to be essentially absorbed, irrespective of the nature of food (beverage and solid food). Apparent digestibility of 50 g iso from two different meals was 95.5 and 98.8 %; apparent absorption was 93.6 and 96.1 %, respectively. In healthy volunteers, a single dose intake of iso resulted in lower postprandial blood glucose and insulin responses than did sucrose (suc), while showing prolonged blood glucose delivery over 3 h test. In a 4-week trial with hyperlipidaemic individuals, regular consumption of 50 g/d iso within a Western-type diet was well tolerated and did not affect blood lipids. Fasting blood glucose and insulin resistance were lower after the 4-week iso intervention compared with baseline. This would be consistent with possible beneficial metabolic effects as a consequence of the lower and prolonged glycaemic response and lower insulinaemic burden. However, there was no significant difference at 4 weeks after iso compared with suc. In conclusion, the study shows that iso is completely available from the small intestine, irrespective of food matrix, leading to a prolonged delivery of blood glucose. Regular iso consumption is well tolerated also in subjects with increased risk for vascular diseases.

Improved metabolic control after 12-week dietary intervention with low glycaemic isomalt in patients with type 2 diabetes mellitus.

The polyol isomalt (Palatinit) is a very low glycaemic sugar replacer. The effect of food supplemented with isomalt instead of higher glycaemic ingredients like sucrose and/or starch hydrolysates on metabolic control in patients with type 2 diabetes was examined in this open study. Thirty-three patients with type 2 diabetes received a diet with foods containing 30 g/d isomalt instead of higher-glycaemic carbohydrates for 12 weeks. Metformin and/or thiazolidindiones were the only concomitant oral antidiabetics allowed during the study. Otherwise, the participants maintained their usual diet during the test phase, but were instructed to refrain from additional sweetened foods. Before start, after 6 weeks and 12 weeks (completion of the study), blood samples were taken and analysed for clinical routine parameters, metabolic, and risk markers. Thirty-one patients completed the study. The test diet was well accepted and tolerated. After 12 weeks, significant reductions were observed for: glycosylated haemoglobin, fructosamine, fasting blood glucose, insulin, proinsulin, C-peptide, insulin resistance (HOMA-IR), and oxidised LDL (an atherosclerosis risk factor). In addition, significant lower nonesterified fatty acid concentrations were found in female participants. Routine blood measurements and blood lipids remained unchanged. The substitution of glycaemic ingredients by isomalt and the consequent on reduction of the glycaemic load within otherwise unchanged diet was accompanied by significant improvement in the metabolic control of diabetes. The present study is in agreement with findings of previous reported studies in human subjects demonstrating beneficial effects of low glycaemic diets on glucose metabolism in patients with diabetes mellitus type 2.

SNP-Array genotyping and spectral karyotyping reveal uniparental disomy as early mutational event in MSS- and MSI-colorectal cancer cell lines.

In this study nine colorectal cancer cell lines were analysed by 10K SNP-arrays and spectral karyotyping (SKY). Complex chromosomal alterations and breakpoints of deleted or translocated fragments found by SKY could further be characterized by SNP-array analysis. Interestingly many monoallelic regions identified by SNP-array analysis display no copy number alterations, representing uniparental disomy (UPD). It was demonstrated that UPD seems to be involved in activation of early-acting tumor suppressor genes in MSS- (APC, CDKN2A) and MSI- (MLH1, MSH2, APC, CDKN2A) colorectal cancer cell lines. Genes involved later on in the adenoma-carcinoma sequence (i.e. TP53/SMAD4) were not found to be inactivated by UPD. Furthermore, identified amplified monoallelic regions may include oncogenes activated by allele-specific-amplification (i.e. Cyclin D1). However, at present, the majority of the monoallelic regions located in the present study have not yet been associated with known tumor suppressor genes and oncogenes. Further studies are warranted to identify relevant genes in the respective regions and to further verify the results presented here.

[The role of the diet in the prevention of gastrointestinal tumors]. / Ernährungstipps zur Prävention gastrointestinaler Tumoren. Obst und Gemüse sind die Favoriten.

Second only to cardiovascular diseases, malignant tumors are the most common fatal disease, with malignant neoplasms in the gastrointestinal tract playing an important role. Underlying the most numerous of these malignancies is a complex interaction between genetic and environmental factors. The data relating to the role of environmental factors (for the most part dietary factors) in the development of gastrointestinal tumors derive mainly from, epidemiological research. The current evidence is "convincin" with regard to complex lifestyle patterns, but at most "plausible" when the chemically defined individual substances are considered. Summarizing the potential protective value of dietary factors reveals that the risk of contracting the majority of the gastrointestinal tumors can be reduced by increasing the intake of fruit and vegetables. An additional protective effect is associated with a balanced diet, physical activity, preservation of normal weight, avoidance of smoking, and moderation in the amount of alcohol consumed.

Effect of starch malabsorption on fecal bile acids and neutral sterols in humans: possible implications for colonic carcinogenesis.

Epidemiological and experimental studies indicate a strong association between an elevated colon cancer risk and increased fecal excretion of secondary bile acids, neutral sterols, and prolonged gastrointestinal transit time. Starch malabsorption, on the other hand, has been reported to be a possible protective factor in colon carcinogenesis. To study the impact of starch malabsorption on these parameters, 12 healthy volunteers consumed a diet rich in starch for two 4-week periods. During a double-blind crossover trial they received the alpha-glucosidase inhibitor acarbose (BAY g 5421) in one of the study periods and placebo in the other. During acarbose treatment stool wet weight increased by 68%, stool dry weight by 57%, and gastrointestinal mean transit time by 30%. Fecal concentrations (mg/g dry weight) of the neutral sterols coprostanol, coprostanone, campesterol, 4-cholesten-3-one, and beta-sitosterol decreased by 36.8, 48.7, 42.1, 34.6, and 39.4%, respectively, under acarbose. Concentrations of the major secondary bile acids, deoxycholic and lithocholic acid, decreased by 59.9 and 52.2%, respectively. In spite of an increased stool weight, also daily excretion (mg/day) of these two bile acids was lower under acarbose (47.9 and 36.6%, respectively) compared to placebo, whereas excretion of the main primary bile acid, cholic acid, rose from 22.58 mg/day to 379.80 mg/day during the acarbose period. The changes in fecal bile acid and neutral sterol excretion found during acarbose treatment may explain a protective effect of starch malabsorption on colon cancer development.

Proliferation of human colonic mucosa as an intermediate biomarker of carcinogenesis: effects of butyrate, deoxycholate, calcium, ammonia, and pH.

A high-fat/high-protein diet has been reported to promote colon cancer by increasing luminal bile acid and ammonia concentrations, whereas butyrate, calcium, and low colonic pH may have protective effects. In this study, bromodeoxyuridine labeling of colonic epithelium was investigated after incubating biopsies from the ascending colon of 70 patients with HCl (20 mM, pH 6.0), butyric acid (H-BUT, 20 mM, pH 6.0), sodium butyrate (Na-BUT, 10 mM, pH 8.0), CaCl2 (10 mM), calcium butyrate (Ca-BUT, 10 mM), ammonium butyrate (NH4-BUT, 10 mM), deoxycholic acid (DCA, 5 microM), and a combination of DCA and Na-BUT (DCA/Na-BUT, 5 microM/10 mM). Compared to NaCl, H-BUT and Na-BUT increased the whole crypt-labeling index significantly, whereas HCl and CaCl2 had no effect. Reduced labeling, however, occurred with Ca-BUT in comparison to equimolar Na-BUT. No differences in the labeling indexes were found for NH4-BUT compared to Na-BUT, but increased labeling with expansion of the proliferative zone to the upper 40% of the crypt was seen with DCA compared to NaCl. DCA-induced hyperproliferation was abolished by coincubation with DCA/Na-BUT. These data suggest that butyrate, calcium, and DCA have complex influences on mucosal proliferation. Since luminal concentrations of these compounds are influenced by dietary interventions, the findings of this study may be of particular interest with regard to colon cancer development and prevention.

Fecal short-chain fatty acid (SCFA) analysis by capillary gas-liquid chromatography.

A new method is described for short-chain fatty acid (SCFA) analysis in stool samples. After sample purification by acid vacuum transfer and concentration by alkaline freeze-drying, SCFAs were measured by gas-liquid chromatography using a capillary column. Peak resolution and reproducibility were superior to SCFA analysis on a conventional glass column. With this new technique SCFA were quantitated in stool samples of six healthy volunteers on a basal diet with and without a fermentable dietary fiber preparation; fiber had no effect on fecal SCFA concentration. In two patients with a short-bowel syndrome, SCFA could be demonstrated in stool samples, indicating active fermentation.

Does yogurt enriched with Bifidobacterium longum affect colonic microbiology and fecal metabolites in health subjects?

Diet-induced changes in the colonic microflora seem to play a role in colon carcinogenesis. In this study the effects of a yogurt (500 mL/d for 3 wk) enriched with Bifidobacterium longum and 5 g lactulose/L (A) on the fecal bacterial flora and various risk indexes for colon carcinogenesis were tested in 12 healthy volunteers and compared with a conventional yogurt (B). Increased excretion of bifidobacteria (P < 0.017) was found after consumption of both yogurts compared with the prestudy periods, whereas cultural counts of aerobes and anaerobes were not different. Breath-hydrogen exhalation was elevated and mouth-to-cecum transit time was accelerated in the period of yogurt A ingestion (P < 0.05) whereas no differences were found for oral-anal mean transit time, stool weight and pH, and fecal concentrations of short-chain fatty acids, bile acids, and neutral sterols. The results generally indicate great stability of the human fecal flora to this kind of dietary intervention.

Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention.

Recent evidence suggests that resistant starch (RS) is the single most important substrate for bacterial carbohydrate fermentation in the human colon. During two 4-wk periods. 12 healthy volunteers consumed a controlled basal diet enriched with either amylomaize starch (55.2 +/- 3.5 g RS/d; high-RS diet) or available cornstarch (7.7 +/- 0.3 g RS/d; low-RS diet). Approximately 90% of the RS consumed disappeared during intestinal passage; increased fermentation was verified by elevated breath-hydrogen excretion. During the high-RS diet, fecal wet and dry weight increased 49% and 56%, respectively (P < or = 0.005), whereas stool water content did not change significantly. Fecal concentrations and daily excretion of short-chain fatty acids were not different in the two study periods. During the high-RS diet, bacterial beta-glucosidase activity decreased by 26% (P < or = 0.05). Fecal concentrations of total and secondary bile acids were significantly lower during the high-RS than during the low-RS period [a decrease of 30% (P < or = 0.05) and 32% (P < or = 0.01), respectively, in total and secondary bile acids] whereas concentrations of primary bile acids were unaffected by RS consumption. During the high-RS diet, fecal concentrations of total neutral sterols decreased by 30% (P < or = 0.005) and fecal concentrations of 4-cholesten-3-one decreased by 36% (P < or = 0.05). These data suggest that RS has potentially important effects on bacterial metabolism in the human colon that may be relevant for cancer prevention.

Effects of sodium selenite on deoxycholic acid-induced hyperproliferation of human colonic mucosa in short-term culture.

It has been shown that in vitro incubation of human colonic biopsies with the secondary bile acid deoxycholic acid (DCA) leads to the hyperproliferation of colonic crypt cells with an expansion of the proliferative zone, which is regarded as a biomarker of increased cancer risk. Sodium selenite (SSE), on the other hand, has been implicated as a protective agent in experimental studies, but toxic effects were reported as well, depending on the dose of SSE. To elucidate the effects of SSE on human colonic mucosa, biopsies from endoscopically normal sigmoid colon tissue of 30 subjects were incubated with 5 microM DCA or a combination of 5 microM DCA and SSE in concentrations of 5, 10, 20, 50, 80, and 100 microM, respectively. Equimolar NaCl incubations served as a control. Proliferating cells were labeled by bromodeoxyuridine immunohistochemistry, and the labeling index (LI) was computed. In the experiments using 5, 10, and 20 microM SSE, the whole crypt LI was significantly lower after DCA + SSE incubation (0.136, 0.118, and 0.110, respectively) compared to that after incubation with DCA alone (0.172, 0.157, and 0.165, respectively; P < 0.01). The corresponding LIs during DCA + SSE incubation were comparable to the LIs obtained after NaCl incubation (average LI = 0.14). Contrary to this finding, severe cell damage was observed in the biopsies that were incubated with the higher SSE concentrations of 50 microM and above. The antiproliferative effects of SSE may indicate a possible protective effect in the prevention of human colon cancer development. However, the observed toxic effects of higher SSE concentrations strongly suggest the need for additional studies before general recommendations for the use of SSE in colon cancer prevention can be made.

Role of short-chain fatty acids in the prevention of colorectal cancer.

Short-chain fatty acids (SCFAs: acetate, propionate, n-butyrate) arising in the large bowel during bacterial fermentation of dietary fibre and starch have paradoxical effects on colonic epithelial proliferation. While the three major SCFAs stimulate proliferation of normal crypt cells, n-butyrate and, to a lesser degree, propionate inhibit growth of colon cancer cell lines. At the molecular level, n-butyrate causes histone acetylation, favours differentiation, induces apoptosis and regulates the expression of various oncogenes. To understand the complex effects of SCFAs on carcinogenesis, it is important to study the intermediate stages of the adenoma-carcinoma sequence where a "switch" from stimulation to suppression of cell proliferation must occur.

Comparisons of the anti-proliferative effects of butyrate and aspirin on human colonic mucosa in vitro.

The short-chain fatty acid butyrate is regarded as a regulative agent in haemostasis of mucosal cell turnover. Inhibition of prostaglandin E2 synthesis is particularly involved in this regulation process. In the present study, proliferation was stimulated in colonic biopsies of 12 healthy subjects (age 51.3 years, range 25-81) by incubation with deoxycholic acid (5 micromol/l DCA). The anti-proliferative and cyclo-oxygenase-inhibiting properties of butyrate (10 mmol/l BUT) and of aspirin (555 micromol/l ASA) were investigated. Colonic cell proliferation was determined by bromodeoxyuridine immunohistochemistry. PGE2 release into the incubation medium was measured by radioimmunoassay. Incubation with DCA/ASA, DCA/BUT and DCA/ASA/BUT revealed a significant reduction in crypt cell proliferation as measured by the labelling index of the whole crypt in comparison to incubation with DCA alone (DCA/ASA: 0.14, P < 0.01; DCA/BUT: 0.15, P < 0.05; DCA/ASA/BUT: 0.15, P < 0.05, versus DCA: 0.18). The labelling index for the upper 40% of the crypt was only lower after incubation with DCA/ASA (0.023) compared to DCA (0.028) (P < 0.05). PGE2 release from biopsy specimens was only significantly decreased in the incubation media where ASA was added (DCA/ASA: 29.0 pg/mg mucosa/h, P < 0.005; DCA/ASA/BUT: 31.4 pg/mg mucosa/h, P < 0.01 versus DCA: 56.9 pg/mg mucosa/h). Butyrate and aspirin showed no synergistic effects. The results indicate a normalization of DCA-induced hyperproliferation of colonic mucosa by butyrate, and, even more efficiently, by aspirin. The data support the hypothesis that butyrate and aspirin can act as chemopreventive agents in colon carcinogenesis.

Antiproliferative effect of 1,4-phenylenebis(methylene)selenocyanate (p-XSC) on colonic epithelium of patients with adenomatous polyps in vitro.

We have consistently shown that the organoselenium compound 1,4-phenylenebis(methylene)selenocyanate (p-XSC) is a superior cancer chemopreventive agent and less toxic than selenite or certain naturally-occurring selenoamino acids. To elucidate the effects of p-XSC on human colonic mucosa, biopsies from endoscopically normal sigmoid colon of 30 patients with adenomatous polyps were incubated with p-XSC at concentrations of 1, 2 and 5 micromol/l dissolved in dimethylsulphoxide (DMSO). Biopsies incubated with DMSO or pure culture medium served as a control. Proliferating cells were labelled by bromodeoxyuridine immunohistochemistry and the labelling index (LI) was computed. Upper crypt labelling index (LI of crypt compartments 4+5) and Phih value, which are both discriminators of the expansion of the proliferative zone, were significantly lower after incubation with 1 and 5 micromol/l p-XSC, respectively (LI 4+5: 0.8 and 1.0; Phih value: 2.1 and 2.4), as compared with DMSO (LI 4+5: 3.6 and 4.5; Phih value: 7.0 and 8.3) or culture medium (LI 4+5: 3.3 and 4.5; Phih value: 7.2 and 8.1) (P<0.005 and P<0.05 by Friedman's block test). A trend towards lower levels of LI 4+5 (P=0.059) and Phih value (P=0.075) were seen after 2 micromol/l p-XSC incubation compared with DMSO. Since hyperproliferation of colonic crypt cells with expansion of the proliferative zone is regarded as a biomarker of increased cancer risk, the antiproliferative effects of p-XSC especially on upper crypt LI and Phih value may indicate a possible protective effect of this organoselenium compound in the prevention of human colon cancer development.

Butyrate and aspirin in combination have an enhanced effect on apoptosis in human colorectal cancer cells.

Laboratory and epidemiological studies suggest that butyrate, a metabolic product of microbial fermentation of dietary fibre, and aspirin, a non-steroidal antiphlogistic drug, both reduce the risk of developing colon cancer. Notably, few data exist on potential interactions of these two substances. In this study, the effects of a butyrate-aspirin combination on human colon cancer cells were compared with treatment with aspirin or butyrate alone. Both substances decreased proliferation and induced differentiation and apoptosis. Butyrate reduced mutant p53 expression, whereas aspirin did not affect p53 expression. Butyrate-induced apoptosis correlated with an increase in Bak expression and a decrease in the expression of Bcl-XL. Aspirin had no effect on the investigated apoptosis-controlling factors. The antiproliferative and pro-apoptotic effects of the butyrate-aspirin combination were markedly enhanced. The combination resulted in a stronger decrease in the expression of PCNA and cdk2. Our data suggest that the anticarcinogenic effect of aspirin might effectively be augmented by combination with the short-chain fatty acid butyrate.

Pattern of epithelial cell proliferation in colorectal mucosa of patients with large bowel adenoma or cancer: an ECP case-control study. European cancer prevention.

Proliferative abnormalities of the normal colorectal mucosa have been proposed as a possible marker of enhanced susceptibility to colorectal cancer. A case-control study was conducted to compare the cell kinetics of normal colon mucosa through the different steps of the adenoma-carcinoma sequence. The number and position of labelled epithelial nuclei after in vitro incubation of tritiated thymidine were compared in patients with large bowel cancer (n = 39), large adenoma >1 cm (n = 47), small adenoma (n = 30) and in controls (n = 135). The distribution of tertiles between cases and controls was analysed using odds ratio (OR), comparing the second tertile (OR2) and the third tertile (OR3) to the first one. There was no significant difference in the overall cell proliferation rate when comparing cancer, large adenoma and small adenoma groups to the control group. The ratio number of labelled cells in the upper 40% of the crypt/total number of labelled cells (4h index) was found to be significantly higher only when the cancer group was compared to the control group: OR2 = 5.87 (1.33-25.90), OR3 = 9.48 (2.07-43.38), P for trend = 0.002. The upward shift of the proliferative compartment in the normal mucosa of patients with large bowel cancer suggests that this abnormality is related to cancer risk.

Faecal neutral sterols and bile acids in patients with adenomas and large bowel cancer: an ECP case-control study. European cancer prevention.

It is unclear whether neutral steroids and bile acids are involved in large bowel carcinogenesis. This study was conducted to compare the concentration of these faecal constituents at the different stages of the adenoma-carcinoma sequence. Neutral sterols and free bile acid concentrations were determined from stool samples collected form patients with large bowel cancer (n = 47), large adenoma > or = 1 cm (n = 42), small adenoma (n = 24), and controls (n = 104). The distribution of tertiles between cases and controls was analysed using odds ratio (OR), with 95% confidence interval (CI), comparing (two-sided tests) the second tertile (OR2) and the third tertile (OR3) to the first one. Persistence of primary bile acids appeared as a protective factor against cancer: (OR = 0.09, 95% CI 0.02-0.54). High values of cholesterol were associated with cancer risk (OR2 = 5.8, 95% CI 1.3-26.6; OR3 6.4, 95% CI 1.3-31.4). High values of cholesterol were more frequently observed in patients with large adenomas than in controls (OR2 = 8.5, 95% CI 1.9-37.5; OR3 = 4.3, 95% CI 0.9-20.9). Neutral sterols, cholesterol especially, may play a role in adenoma growth and adenoma transformation into carcinoma. Persistence of primary bile acids may afford protection.