Dietary factors in human colorectal cancer

Colorectal cancer is a significant cause of mortality in Western societies. The progression of the disease from normal colonic epithelium to the acquisition of the malignant phenotype is accompanied by numerous genetic and epigenetic alterations. Compelling experimental and epidemiological evidence indicates that diet and nutrition are key factors in the modulation of colorectal cancer. A salient case in point is the recent observation that a dietary regimen based on a Western-style diet provokes in the rodent colon the appearance of preneoplastic lesions in the absence of any genotoxic insult. This review mainly describes dietary factors that inhibit the development and progression of colorectal cancer. Much is unknown about the precise mechanisms of action of chemically disparate nutrients and how they interfere with the development and progression of this disease. Current knowledge about this important issue is summarized. We believe that continuing scrutiny and precise assessment of the benefits (and potential risks) of nutrients in the treatment and prevention of colorectal cancer will prove significant to controlling this devastating disease.

Rectal cancer mortality and total hardness levels in Taiwan's drinking water

The possible association between the risk of rectal cancer and hardness levels in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with deaths from other causes (986 controls), and the hardness levels of the drinking water used by these residents were determined. Data on water hardness throughout Taiwan were collected from Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes and the controls were pair matched to the cases by sex, year of birth, and year of death. The results show a significant negative relationship between drinking water hardness and rectal cancer mortality. Odds ratio and 95% confidence intervals were 1.24 (1.01-1. 55) and 1.38 (1.10-1.73), respectively, for exposure to moderately hard water and soft water compared with the use of hard water. Trend analyses showed an increasing odds ratio for rectal cancer with decreasing levels of hardness in drinking water. This is an important finding for the Taiwan water industry and human health.

Cumulative risk of developing polyps or malignancy at the ileal pouch-anal anastomosis in patients with familial adenomatous polyposis

Restorative proctocolectomy with an ileal pouch-anal anastomosis is performed in an increasing number of patients with familial adenomatous polyposis (FAP). Two techniques are currently used to construct an ileal pouch-anal anastomosis: (1) a double-stapled anastomosis between the pouch and the anal canal and (2) mucosectomy with a hand-sewn ileoanal anastomosis at the dentate line. Although this procedure is thought to abolish the risk of colorectal adenoma, an increasing number of case reports have been published concerning the development of adenoma at the anastomotic site. The purpose of this study was to evaluate the overall cumulative risk of developing adenomatous polyps after ileal pouch-anal anastomosis and to compare the cumulative risk after either anastomotic technique. A total of 126 consecutive FAP patients undergoing a restorative proctocolectomy were identified from polyposis registries in The Netherlands, Denmark, Italy, Germany, and New York. Life-table analysis was used to calculate the cumulative risk of developing polyps in 97 patients with at least 1 year of endoscopic follow-up (median 66 months, range 12 to 188 months). A double-stapled anastomosis was used in 35 patients, whereas in 62 patients a hand-sewn anastomosis with a mucosectomy was performed. In 13 patients polyps developed at the anastomotic site, four with severe and four with moderate dysplasia. None of the patients developed a carcinoma at the anastomotic site. The cumulative risk of developing a polyp at the anastomotic site was 8% (95% confidence interval 2% to 14%) at 3.5 years and 18% (95% confidence interval 8% to 28%) at 7 years, respectively. The risk of developing a polyp at the anastomotic site within 7 years was 31% for patients with a double-stapled vs. 10% for patients with a hand-sewn anastomosis with mucosectomy (P = 0.03 [log-rank test]). Because FAP patients undergoing a restorative proctocolectomy with either a double-stapled or hand-sewn anastomosis have a substantial risk of developing adenomatous polyps at the anastomotic site, lifelong endoscopic surveillance is mandatory in both groups.

[Screening for cancer]

Screening can be defined as the process of identifying preclinical disease in asymptomatic people. The main objective of screening is to reduce the incidence and the mortality from disease. There are several prerequisites for successful screening, and screening has both beneficial and adverse effects. In Norway only screening for cervical and breast cancer are recommended as nation-wide, organised programmes. Screening for colorectal cancer is planned as a pilot project. Also a study on screening for prostate cancer is planned. Screening for other cancers is not recommended.

Dietary fiber and the risk of colorectal cancer and adenoma in women

BACKGROUND

A high intake of dietary fiber has been thought to reduce the risk of colorectal cancer and adenoma.

METHODS

We conducted a prospective study of 88,757 women, who were 34 to 59 years old and had no history of cancer, inflammatory bowel disease, or familial polyposis, who completed a dietary questionnaire in 1980. During a 16-year follow-up period, 787 cases of colorectal cancer were documented. In addition, 1012 patients with adenomas of the distal colon and rectum were found among 27,530 participants who underwent endoscopy during the follow-up period.

RESULTS

After adjustment for age, established risk factors, and total energy intake, we found no association between the intake of dietary fiber and the risk of colorectal cancer; the relative risk for the highest as compared with the lowest quintile group with respect to fiber intake was 0.95 (95 percent confidence interval, 0.73 to 1.25). No protective effect of dietary fiber was observed when we omitted, adjustment for total energy intake, when events during the first six years of follow-up were excluded, or when we excluded women who altered their fiber intake during the follow-up period. No significant association between fiber intake and the risk of colorectal adenoma was found.

CONCLUSIONS

Our data do not support the existence of an important protective effect of dietary fiber against colorectal cancer or adenoma.

Independent and joint effects of family history and lifestyle on colorectal cancer risk: implications for prevention

It has been suggested that, for a substantial proportion of "sporadic" colorectal cancers (CRCs), inheritance determines individual susceptibility and that lifestyle determines which susceptible individuals express cancer. Because the genetic basis of this inherited susceptibility remains undefined, we used family history of the disease as a proxy for a genetic predisposition to examine its interactions with a variety of lifestyle factors in a large population-based case-control study of CRC. The subjects were 698 male and 494 female Japanese, Caucasian, Filipino, Hawaiian, and Chinese patients diagnosed with CRC in Hawaii during 1987-1991 and 1192 population controls matched to cases on age, sex, and ethnicity. Fourteen percent of the cases and 6% of the controls reported a family history of CRC among parents or siblings. After adjusting for other covariates, significant interactions with family history were found for beef and ethanol intakes in males (P = 0.03). Relative to men without a family history and whose intake fell in the lower third, odds ratios (ORs) for CRC for men with a family history and in the upper tertile of intake were 10.8 [95% confidence interval (CI), 4.2-27.6] and 7.5 (CI, 3.1-18.2) for beef and ethanol, respectively. The corresponding ORs for men without a family history and in the upper tertile were 1.5 (CI, 1.0-2.3) and 1.4 (CI, 1.0-1.9), respectively. No interactions were detected in women. Using a summary measure of lifestyle, we found that family history was not associated with CRC among men who were at the lower-risk tertile for all of the lifestyle risk factors. In contrast, the OR for men with a family history and at the higher-risk tertile for all of the lifestyle variables was 11.7 (CI, 5.8-23.9). In the absence of a family history, this OR was 4.8 (CI, 3.2-7.2). These data suggest that family history increases the risk of sporadic CRC in men mainly through its interaction with lifestyle exposures, primarily a high beef and ethanol intake, and are consistent with recent reports of effect modifications of dietary associations by metabolic genes. Computation of population attributable risks also suggested that a comprehensive reduction in exposure to lifestyle risk factors--and more specifically to ethanol and beef for individuals with a familial predisposition for the disease--may have a large beneficial effect on CRC incidence.

Colorectal cancer--chemoprevention

Colorectal cancer is the second leading cause of death from cancer in The United States. During the last fifteen years, emphasis has been placed on identification of high risk patients and families and outline of appropriate surveillance regimens for normal and high risk patients for colorectal cancer. Parallel to this effort, abundant clinical data has been accumulated that chemoprevention of colorectal cancer with nonsteroidals and aspirin may be possible. Interruption of prostaglandin metabolism appears to be one of the mechanisms of action but not the only therapeutic arm. Currently, sulindac, aspirin, calcium and selenium supplementation are attractive recommendations to at risk patients awaiting results of clinical trials. Other agents in development add excitement to the concept of colorectal cancer chemoprevention.

Urinary tract cancer and hereditary nonpolyposis colorectal cancer: risks and screening options

PURPOSE

We investigate the risk of the different types of urinary tract cancer in hereditary nonpolyposis colorectal cancer families and review screening options.

MATERIALS AND METHODS

We retrospectively calculated the relative and cumulative risks of developing urinary tract cancer by comparing tumor occurrence in patients and their first degree relatives in the Dutch hereditary nonpolyposis colorectal cancer registry with those in the general Dutch population. A person-year analysis was used, including data on 1,321 individuals from 50 hereditary nonpolyposis colorectal cancer families.

RESULTS

The relative risk of developing transitional cell cancer of the renal pelvis or ureter was 14.04 (95% confidence interval 6.69 to 29.45, p <0.05) and the cumulative risk was 2.6%. The risks of renal (excluding renal pelvis) and bladder cancers were not significantly increased. Urinary tract cancer was diagnosed at a relatively young age and many women were affected. Some familial clustering was observed.

CONCLUSIONS

Our findings indicate that hereditary nonpolyposis colorectal cancer is associated with an increased risk of transitional cell cancer of the upper urinary tract. The cumulative risk is relatively low, although a subset of hereditary nonpolyposis colorectal cancer families may be exposed to a much higher risk. As yet nothing is known of the clinical impact of screening for urinary tract cancer in cases of hereditary nonpolyposis colorectal cancer. In a research setting screening by excretory urography of hereditary nonpolyposis colorectal cancer families with a strong history of upper urinary tract cancer should be considered.

Population based randomized study of uptake and yield of screening by flexible sigmoidoscopy compared with screening by faecal occult blood testing

OBJECTIVES

To compare the feasibility of mass screening by flexible sigmoidoscopy with screening by faecal occult blood testing (Haemoccult) and both tests combined.

DESIGN

Patients were randomised to screening by flexible sigmoidoscopy, faecal blood testing, or both tests. The flexible sigmoidoscopy examinations were performed by a general practitioner.

SETTING

General practice.

SUBJECTS

3744 patients aged 50-75 years.

MAIN OUTCOME MEASURES

Uptake, positive results, detection of neoplasia, complications, and recall for diagnostic colonoscopy.

RESULTS

Uptake was significantly higher in the flexible sigmoidoscopy group (46.6%) than in the faecal blood test group (31.6%; P<0.001) or than in the group having both tests (30.1%; P<0.001). Telephone reminders increased uptake of sigmoidoscopy to 61.8%. In total, 1116 sigmoidoscopy examinations were performed without major complication. Polyps were found in 19. 3% (95% confidence interval 17.0% to 21.6%) but only 6.8% (5.3% to 8. 3%) had adenomas and 2.4% (1.5% to 3.3%) "high risk" adenomas. Cancer was detected in four subjects. The faecal blood test yielded positive results in 0.8% (0.2% to 1.4%) but missed at least one cancer and 30 cases of adenoma which were found by sigmoidoscopy in the combined group. Use of histological criteria-shown elsewhere to correlate with future risk of colorectal cancer-to select "positive" patients could reduce recall for diagnostic colonoscopy from about 20% to less than 5%.

CONCLUSIONS

Some of the predicted obstacles to screening with flexible sigmoidoscopy are surmountable. Clear evidence relating to efficacy will be obtained only from a randomised controlled trial.

[Colorectal cancer mortality can be reduced. Fecal blood screening is an efficient test]

Findings in large randomised studies in Europe and America show that colorectal cancer mortality can be reduced by faecal occult blood screening. Moreover, in the American study it was shown for the first time that the risk of colorectal cancer is reduced by removal of benign polyps larger than 9 mm. Partly as a result of uncontrolled studies showing repeat examination with the rigid rectoscope and removal of benign adenomas to reduce the risk of cancer, flexible sigmoidoscopy has been adopted in two controlled studies, one British the other American, though the problem remains of diagnosing the 30-40 per cent of tumours that are inaccessible to the sigmoidoscope. Together, the two types of hereditary colorectal cancer, familial adenomatous polyposis and hereditary non-polyposis colon cancer, account for only 5-10 per cent of all colorectal cancer, the overwhelming majority of cases being sporadic.

Nonsteroidal antiinflammatory drug use and reduced risk of large bowel carcinoma

BACKGROUND

Animal experiments and epidemiologic data have suggested that the use of nonsteroidal antiinflammatory drugs (NSAIDs) may decrease the incidence of large bowel carcinoma. Our purpose was to assess the relation of the use of aspirin and nonaspirin NSAIDs with the risk of large bowel carcinoma.

METHODS

A population-based case-control study of colon and rectal carcinoma was conducted in Massachusetts from 1992 to 1994. Data on NSAID use and risk factors for large bowel carcinoma were collected by interview from 1201 incident cases of large bowel carcinoma and 1201 controls matched by age, gender, and area of residence.

RESULTS

Regular NSAID use that continued into the year before diagnosis was associated with a significantly decreased relative risk estimate overall (0.7; 95% confidence interval [CI], 0.5-0.8) and among Stage II-IV tumors (0.6; 95% CI, 0.4-0.7). There was no reduction in risk for discontinued use. The inverse association with regular continuing use was present across age and gender and for both colon and rectal carcinoma. Similar inverse associations were present for regular continuing use of aspirin and nonaspirin NSAIDs. There was no significant evidence of a trend for the relative risk to decrease as the duration of use increased, nor was there a trend across the dose of aspirin, which ranged from less than one-half of a 325 mg tablet per day to > or = 2 tablets per day. Discontinuation of use in response to symptoms of carcinoma did not appear to explain the inverse association, nor did bias related to diagnosis of the carcinoma.

CONCLUSIONS

These data add to the growing body of evidence that suggests a protective effect of NSAIDs against large bowel carcinoma.

[Treatment of colorectal cancer. Pharmaco-economic aspects]

Cancer patients care is mainly based on scientific studies, but sometimes approaches are empiric. Rapid growth of health care expenses force the physician to take pharmacoeconomic aspects into consideration. New clinical studies have to analyse clinical benefits but also cost-effectiveness. We will review the various aspects of colorectal cancer from primary prevention to post-treatment follow-up. Scientific data are integrated in a pharmacoeconomic analysis.

Stage I rectal cancer: identification of high-risk patients

BACKGROUND

Stage I rectal cancer (T1, T2 N0) is currently treated by surgical resection alone. Despite adequate surgical resection, approximately 10-15% of patients will develop recurrence. Identification of patients at high risk for recurrence could potentially lead to an improvement in outcome by selection of these patients for adjuvant therapy.

METHODS

Between June 1986 and September 1996, 211 patients with primary rectal cancer (stage I) were treated by radical surgical resection alone. The medical data of all patients were entered into a database and prospectively followed. The following 10 prognostic factors were correlated with recurrence and tumor-related mortality: patient factors: age, gender, and preoperative carcinoembryonic antigen level; tumor factors: location from the anal verge (< 6 cm vs. > or = 6 cm), T stage (T1 vs. T2), intratumoral blood vessel invasion (BVI), intratumoral lymphatic vessel invasion, presence of tumor ulceration, and histologic differentiation; and treatment-related factors: extent of surgical resection--abdominal perineal resection versus low anterior resection. Univariate analysis of the effect of the prognostic factors on recurrence and tumor-related mortality were performed by the method of Kaplan-Meier and log rank test. Independent prognostic factors were determined by a multivariate analysis performed using the Cox proportional hazards model.

RESULTS

The overall 5-year actuarial recurrence was 12% and tumor-related mortality was 10%. Independent predictors of recurrence were male gender and BVI. Independent predictors of tumor-related mortality were male gender, BVI, and poorly differentiated tumors.

CONCLUSIONS

Despite radical resection, patients with stage I rectal cancer with male gender, BVI, and poorly differentiated tumors should be considered high-risk patients.

Role of different types of vegetables and fruit in the prevention of cancer of the colon, rectum, and breast

We compared the effect of 26 types or groups of vegetables and fruit on the risk of cancer using data from two case-control studies that included 1,225 cases of cancer of the colon, 728 cases of cancer of the rectum, 2,569 cases of cancer of the breast, and 5,155 hospital controls interviewed between 1991 and 1996 in six Italian areas. Most vegetables were inversely associated with cancer of the colon and rectum, whereas only carrots and raw vegetables lowered breast cancer risk. High fruit intake was associated only with a reduction of rectal cancer. Different contents of sugar, fiber, carotenoids, and folic acid in fruits vs vegetables plus the concurrent consumption of oil with vegetables may partly explain these findings.

Aspirin and gastrointestinal cancer

In rodents, nonsteroidal anti-inflammatory drugs (NSAIDs) including aspirin inhibit chemically induced adenomas and early carcinomas of the colon. The NSAID Sulindac inhibits the growth of polyps of the colon and rectum in two randomized trials of patients with familial adenomatous polyposis (FAP), although the inhibition is not complete. Eight epidemiologic studies have found a 40-50% reduction in polyps or colorectal cancer among persons who regularly use aspirin or other NSAIDs compared to those who do not. Two epidemiologic studies show a slight increase in risk. Interpretation of the epidemiologic studies is complicated, because bleeding induced by aspirin may enhance the diagnosis and early treatment of cancer, and at least in theory, the symptoms of cancer could cause patients to avoid aspirin. Clinical trials designed specifically to investigate the aspirin hypothesis in humans at high risk of colorectal polyps or cancer are needed to establish causality, and to define the optimal dose and drug. Experimental studies should further define the mechanism of tumor inhibition in animals.

[How I treat colorectal cancer. I. Prevention and adjuvant treatment]

Colorectal adenocarcinoma is a major cause of cancer-related morbidity and mortality in Belgium and in other western countries. Prevention implies a modification of alimentation and maybe a chronic uptake of acetylsalicylic acid. Treatment of colorectal cancers is based on surgery and the prognosis is determined by the locoregional or metastatic tumor spread. Complete resection of any Astler Coller stage C colorectal malignant tumor has to be followed by a 5-fluorouracil-based adjuvant chemotherapy. In these protocols, 5-fluorouracil is administered together with folinic acid or levamisole. The administration of an adjuvant chemotherapy could also be considered for stage BII diseases. As rectal cancers are characterized by high local relapse rates, their treatment should associate radiotherapy, given either post-surgery or preferentially pre-surgery, with resection and chemotherapy. Appropriate treatment of colorectal cancers thus requires a concerted multidisciplinary approach.

How to screen for colon cancer

The biology of colorectal cancer provides a unique opportunity for early detection and prevention. There is now evidence that screening of asymptomatic average-risk individuals over 50 years of age can reduce mortality resulting from colorectal cancer. New recommendations from the US Preventive Services Task Force endorse screening with fecal occult blood tests or sigmoidoscopy. The best method for population screening remains uncertain. The cost of screening is an important issue in the development of public policy. This review discusses the various screening options, examines the "downstream" effects of screening, and reviews the anticipated costs and effectiveness. Ultimately, the effectiveness of any screening program depends on patient compliance. Further research is needed to determine the best methods of enhancing patient adherence to a screening program.

A prospective cohort study of intake of calcium, vitamin D, and other micronutrients in relation to incidence of rectal cancer among postmenopausal women

To investigate whether high intakes of calcium and other micronutrients (carotene, retinol, and vitamins C, D, and E) are related to reduced risks of rectal cancer, we analyzed data from a large cohort study of postmenopausal Iowa women who responded to a mailed survey in 1986. After 9 years of follow-up, 144 incident rectal cancer cases were ascertained among the 34,702 women at risk. Intake levels of micronutrients at baseline were derived from self-reported data on vitamin supplements and dietary intake of 127 foods included in a semiquantitative food frequency questionnaire. After adjustment for total energy intake and other potential confounding factors, a dose-response inverse association was observed between total calcium intake and the risk of rectal cancer: adjusted relative risks (RRs) were 1.00, 0.90, and 0.59 (trend test, P = 0.02) from the lowest to the highest calcium intake tertiles. High intakes of dietary and supplement calcium were both related to a slightly reduced risk of rectal cancer, but neither of the trend tests was statistically significant. Reduced risks of rectal cancer were also observed for high intake of carotene and vitamins A, C, and D, although none of the associations were statistically significant. For vitamin D, the adjusted RRs were 1.00, 0.71, and 0.76 (trend test, P = 0.20) for increasing intake tertiles. Compared with women who consumed low levels of both total calcium and vitamin D, those in the highest intake group of both nutrients were at a 45% reduced risk of rectal cancer (RR, 0.55; 95% confidence interval, 0.32-0.93). This study supports the hypothesis that high intake of calcium and possibly other micronutrients may be beneficial in the prevention of rectal cancer.