[Colorectal cancer. Knowledge of the public and acceptability of early detection in non-hospital medical practice]

Six general practitioners attached to a day-care center investigated the extent of their patient's knowledge concerning colorectal cancer and the degree of cooperation to be expected in a screening program. An eight-week information campaign was organized in the neighborhood from which 60 p. cent of their patients were drawn, along with free access to a guaiac test for people aged forty and over. Surveys conducted before the campaign and six months after, revealed how well- or ill-informed the local people were. Immediately after the campaign a screening program combining rectosigmoidoscopy with guaiac test was proposed to patients aged forty and over. Their level of cooperation was studied over a period of three years. Before the campaign 4.5 p. cent of those interviewed were afraid of contracting colorectal cancer, while 14.5 p. cent considered it to be frequent. After the campaign, 13.5 p. cent of people interviewed as opposed to 4.4 p. cent before (p less than 0.001) knew polyps to be precancerous lesions; 22.6 p. cent, as opposed to 2.4 p. cent before (p less than 0.001) mentioned the search for occult blood in the feces as a screening method. Their knowledge of endoscopy remained unchanged (mentioned by 15.5 p. cent of the people interviewed). During the campaign, 8.6 p. cent of people in the neighborhood of forty and upwards carried out a test. Seventy-five (2 p. cent) of the 3,860 people aged forty and over who consulted a general practitioner at least once during the three-year period following the campaign underwent the full screening program.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutrition in the prevention of neoplastic disease in the elderly

This review focuses on specific effects of diet on cancer risk and the relevance of these dietary effects to the risk of cancer in the elderly. The authors address the impact of certain dietary factors on cancer risk by reviewing their roles in two distinct phases of carcinogenesis: "imitation" and "promotion."

[Summary of a new assessment strategy in positive occult blood tests in mass screening]

Effective regulations of the Federal Association of Health Insurance Physicians (Kassenärztliche Bundesvereinigung) require prompt evaluation of positive fecal occult blood tests (FOBTs) in the nationwide cancer screening programme using rectoscopy, double contrast barium enema and colonoscopy, the latter occasionally being recommended as a primary investigation. In symptomless screenees the prevalence of positive FOBTs is much higher than that of detected malignancies. Hence a major proportion of all follow-up investigations are negative. A simple model yields the following conclusion: waiving immediate and maximum follow-up efforts in favour of a two-stage screening procedure will result in a loss of some detectable cases; on the other hand, the number (and with it inconveniences, risks, and costs) of follow-up investigations may be reduced to such an extent that a two-stage screening programme along with some modifications of the FOBT itself should be tested.

Case-control study of dietary etiological factors: the Melbourne Colorectal Cancer Study

As part of a large-scale investigation of colorectal cancer (CRC) incidence, etiology, and survival, a case-control study was conducted to identify dietary factors associated with the risk of CRC. The study compared 715 cases with 727 age- and sex-matched community controls. A quantitative diet history, assessed to be the most representative of the previous 20 years, was obtained from each subject and analyzed for both food groups and nutrients. The combination of a high-fiber and high-vegetable intake was found to be protective against large bowel cancer. Cruciferous vegetable intake was also found, although with less certainty, to be protective. Dietary vitamin C was protective for estimated intakes greater than 230 mg/day. Dietary Beta-carotene had no separate association with the risk of CRC. Beef intake was a risk factor in males but not in females. Fat intake was a risk factor for both males and females. A low intake of milk drinks was a risk for both males and females. A high intake of pork and fish was protective. The use of vitamin supplements was highly protective. A risk score, which was calculated as the number of risk factors an individual has in his or her diet, showed an increasing monotonic relationship with risk of CRC. The effects of the dietary variables were similar for colon and rectal cancer and, with the exception of beef, were similar for males and females.

Multicenter evaluation of training of non-endoscopists in 30-cm flexible sigmoidoscopy

An estimated 145,000 patients will be diagnosed with colorectal cancer in the United States in 1987. Although half of these cancers are potentially detectable by sigmoidoscopy, rigid sigmoidoscopy is not widely used for early detection, largely because of discomfort it causes patients. Flexible sigmoidoscopy has been shown to be more acceptable and more efficient in detecting cancers. In order for flexible sigmoidoscopy to be of more value in cancer control, however, primary care physicians must learn the technique and incorporate it into their complete physical examinations. This paper reports the results of a multicenter trial that evaluated the training required for non-endoscopists to learn how to use the 30-cm flexible sigmoidoscope. Instructions with plastic models, followed by an average of six supervised patient examinations, proved sufficient for them to learn the necessary skills.

The nutritional causes of colorectal cancer: an introduction to the Melbourne study

The Melbourne study has shown that dietary factors and alcohol are important in the cause and prevention of colorectal cancer (CRC). A high intake of fat and beef probably causes CRC, and a high intake of beer possibly causes rectal cancer. The beef and beer effects were both independent of other dietary variables, but further research is indicated to explore the mechanisms of their actions. Foods of plant origin protected against CRC, and the "plant food hypothesis" now replaces the dietary fiber hypothesis. Further study is needed on the interrelationships between various foods of plant origin. Vitamin supplements were protective, and again clarification is needed on the mechanism of action. In high-risk populations, nutritional risk and causal factors are likely to be difficult to find, whereas protective factors are likely to be found with greater ease. Further analysis of the Melbourne data will reveal the importance of diet in CRC causation, relative to the other hypothesized causal and protective factors.

Chemoprevention of colorectal neoplasms. Ascorbic acid and beta-carotene

The organospecific, 1,2-dimethylhydrazine-induced rat tumor model was used to test tumor formation in groups of animals receiving regular chow, powdered chow with 7%/wt ascorbic acid supplement, pelleted chow with 1%/wt beta-carotene supplement, and pelleted chow with placebo beadlets. Following a 16-week induction period, animals were killed and tumor formation was recorded. Tumor formation in the ascorbic acid supplement group was found to be significantly less than the control group. The beta-carotene group showed no difference in tumor formation compared with the placebo-beadlet control group. Tumor incidence was generally the same between the two control groups, and the ascorbic acid group had significantly fewer tumors than the beta-carotene group. In sum, ascorbic acid supplements in high doses significantly decreased tumor formation, whereas beta-carotene supplements in moderately high doses had no effect on tumor formation in this model.

A comparison of the macrophage migration inhibition (MMI) assay and the semi-automated leucocyte adherence inhibition (SALAI) assay

The present study was undertaken in order to compare simultaneously the semi-automated leucocyte adherence inhibition (SALAI) assay with the two-stage macrophage migration inhibition (MMI) assay in patients with colorectal disease. Eighty-six patients were assayed simultaneously in the MMI assay and the SALAI assays using patients' leucocytes and 83 patients were assayed simultaneously in the MMI assay and the SALAI assay using patients' serum. The SALAI assay using patients' leucocytes was more sensitive (70% vs 40%) and more specific (87% vs 73.3%) than the MMI assay. The SALAI assay was simple to perform, allowed many replicate samples and was more specific and sensitive in relation to the detection of colorectal cancer than other more commonly advocated tests. It may be useful as a screening test for colorectal cancer and it is suggested that further studies should be undertaken in this area.

Participation in mass screening for colorectal cancer with fecal occult blood test

A Danish, randomized study with Hemoccult-II, including 60,000 persons between 45 and 74 years old, began in 1985. Methods of increasing acceptability are described for the first 8000. The first 1000 refusals are also analyzed. Written invitations including prestamped envelopes for return of the slides resulted in an acceptability of 58.8%. Two reminders increased the figure to 65.6%. Personal attempts to change the mind of those refusing increased the last figure to 68.9%. Incomplete slides were returned by 49 persons, but on request 43 sent a complete set. All 78 persons with positive tests had colonoscopy, which detected carcinomas in 10 and adenomas in 39. The study confirmed that results of trials from different countries are difficult to compare because of major differences among populations and methods. However, the present results were similar to those obtained in a Swedish study including only persons between 60 and 64 years old.

Colorectal cancer. A blueprint for disease control through screening by primary care physicians

The Virginia Colorectal Cancer Control Project is a statewide effort to reduce morbidity and mortality from colorectal cancer by stimulating the adoption of screening and early detection practices by primary care physicians. The project emphasizes use of the three-day fecal occult blood test, digital rectal examination, and endoscopy. Recruitment strategies included personal contact, newsletters, journal articles, and screening workshops. Of the 33 318 patients screened over 26 months, positive fecal occult blood test reactions were recorded in 3.3% of asymptomatic patients and in 14.8% of symptomatic patients. Polyps were found in 149 and cancer was diagnosed in 94 patients of whom one third were asymptomatic. Eighty percent of the latter had Dukes' A and B lesions, 12% had Dukes' C lesions, and 8% had Dukes' D lesions. In contrast, only 36% of the symptomatic cancers were Dukes' A and B lesions, and 69% were Dukes' C and D lesions. These results suggest that primary care physicians can be effective in the screening and detection of precancerous polyps and early-staged colorectal cancers.

Fluorouracil in chemoprophylaxis of colorectal cancer. Results of a controlled clinical trial

In a randomized prospective clinical trial in 128 patients undergoing radical surgical resection of primary colorectal cancer, 63 patients received intravenous fluorouracil (5-FU) in two courses, four and eight weeks after surgery; 65 controls received no chemotherapy. The duration of follow-up exceeded five years in all cases, and 28 patients have died in each group. Recurrent disease was present in 26 5-FU patients (41.2 percent) and in 22 controls (33.9 percent). There is no evidence that short-term 5-FU therapy was of significant value in the chemoprophylaxis of colorectal cancer.

[Empirical study of the assessment of diagnostic procedures as exemplified by the Hemoccult test]

We offered a questionnaire to 52 physicians in order to study the appreciation of the fecal occult blood test as an example of a diagnostic procedure. We asked for an indication of the overall appreciation of the test, and for an estimation of the probabilities of colorectal cancer before the test and with a positive or a negative test result--each of them for three situations with different a priori probabilities. The answers demonstrated that the estimated value of the test, representing the personal experience of the physicians is very low (predictive factor between 0.61 and 0.78). About half of the physicians' estimations showed no improvement of probability by using Haemoccult. This contrasts with the expressed very positive general opinion about Haemoccult testing, including its use in symptomatic patients. This result underlines the necessity of careful evaluation of diagnostic tests.

Screening of colorectal cancer

Colorectal cancer (CRC) remains a cancer in a disappointing location. However, its location clearly has an advantage that could theoretically permit efficient secondary prevention: the preceding of the cancer by a benign lesion, ie, the adenoma. Complete colonoscopy and its substitute, the double-contrast barium enema, and their specific limitations, must be reserved for high-risk patients: hereditary cancers and ulcerative colitis. For all the others, ie, adults of 45 years of age and with standard risks, the proposal is either to select the patients to be colonoscoped through occult blood testing of the stools or to perform a fiber sigmoidoscopy or a combination of both. Although imperfect, both methods allow the detection of polyps and cancers at a presymptomatic stage, when they are either benign or malignant, but localized and with a better prognosis. However, the absolute proof of the benefits of this strategy of screening would be the demonstration by controlled studies of a prolonged survival rate or a decrease in morbidity. Until now, this proof is not fully available.

Results of surgical treatment for familial polyposis coli

Seventy-seven patients with polyposis coli operated on at The Mount Sinai Hospital in the last 40 years were studied. Forty-two patients had a subtotal colectomy. Sixteen were found to have colon cancer at the time of operation, and a second rectal cancer developed in 50 percent of the survivors within 1 to 13 years after subtotal colectomy. Rectal cancer subsequently developed in only 3 of 23 patients without colon cancer. Thirty-five patients had total proctocolectomy or total colectomy with mucosal proctectomy and ileoanal anastomosis. Recurrent adenomatous polyps developed in two patients after mucosal proctectomy. A villous adenoma with carcinoma in situ of the ileum developed in one patient 30 years after total proctocolectomy and ileostomy. Another patient died from a periampullary carcinoma 24 years after subtotal colectomy. It seems that as the life expectancy of patients with polyposis improves, the incidence of small bowel and duodenal cancers may be expected to increase.

Sensitivity of fecal hemoccult testing and flexible sigmoidoscopy for colorectal cancer screening

Fecal Hemoccult testing and flexible sigmoidoscopy have been proposed as means of screening for colorectal cancer in the general population, as well as in identified high-risk groups. A colorectal cancer screening program was conducted for the Pattern Makers' League of North America. A total of 1,473 white males were screened with fecal Hemoccult testing and flexible sigmoidoscopy during the period 1981 to 1983. The fecal Hemoccult test after diet restriction was positive in 38 workers (2.6%). Among 12 colorectal cancers, including in situ cases, only three were positive by this test. The sensitivity of this test for picking up cancer is only 25%. The positive predictive value was 7.9%. It is concluded that the Hemoccult test for the detection of colorectal cancer and polyps is not a valuable tool because of low sensitivity, whereas flexible sigmoidoscopy has a significant role in colorectal cancer screening of an asymptomatic population at risk.

Screening for colorectal cancer and polyps among pattern makers

In response to a union request, a cancer screening program was conducted for the Pattern Makers' League of North America. Ten colon cancer cases were detected among the 1,465 white men screened with a flexible sigmoidoscope. The difficulties in obtaining appropriate "expected" numbers were that prevalent detectable preclinical colon cancer is not equivalent to incident disease, and the flexible sigmoidoscope yields results not directly comparable to those of the rigid sigmoidoscope used previously. The "expected" number of cancers was obtained by using an independent estimate of 5 years for the mean duration of the detectable preclinical phase. This implied that the expected number of colon cancer cases should be based on the age-specific incident rates among white men in the next-older 5-year age group and that the annual expected number should be multiplied by five. Therefore, the ten observed cases of colon malignancies represented an approximately threefold increase. For invasive cancer only, there was a slightly less than twofold cancer increase. Fifteen percent of the men had one or more colorectal polyps.