The prevention of colon cancer

Detection of synchronous carcinomas of the colon with F-18 fluorodeoxyglucose: a case report

Colon and rectal carcinomas are common in North America and Northwestern Europe. In South America, the risk of this disease is not as great. Adenocarcinomas are the most common types of tumors, and they occur mainly in the descending colon, sigmoid, and rectum. A patient with a possible right colon carcinoma was examined using F-18 FDG.

Elective surgery for gastrointestinal tumours in the elderly

The geriatric population is expanding and clinical decision-making is often complicated by the effects of ageing. Age should not be the only parameter considered when addressing medical problems. Elderly subjects have been denied surgery because of their presumed higher mortality and morbidity. The present review summarises the physiology of the aged and discusses operative risks, mortality and morbidity rates as well as therapeutic results for the different gastrointestinal sites when affected by cancer. Reports on surgical treatments are revisited and compared to the same procedures delivered to younger patients in the context of the ethical issue of offering the best care to every patient. Elective operations by surgical oncologists are found to be safe with the exception of major liver resections. Complication rates and mean hospital stay do not differ between the two age groups provided the procedure is conducted with the best-known technique in expert hands. A drop in operative morbidity has occurred in the past three decades. Several investigators have emphasised the marked increase in morbidity and mortality experienced by elderly patients when undergoing emergency procedures. Associated diseases have to be properly assessed, as the elderly have a frail physiological balance with a reduced capacity for recovery from traumatic events including major surgical procedures. Careful preoperative evaluation, intraoperative conduct and postoperative care are presently achieved in almost every major hospital. Good clinical practice is based on the balance between probability of cure and toxic effects. Treatment of the elderly should no longer be based on untested beliefs and personal opinions. The elderly should be accrued for prospective clinical evaluation and should not be denied optimal surgical treatment.

Sigmoidoscopy and other tests for screening of colorectal cancer

We have been carrying our mass detection for colorectal cancer with fecal occult blood test and sigmoidoscopy. The occult blood test is negative in 60% with colorectal cancer.

Single-visit screening and treatment of first-degree relatives. Colon cancer pilot study

A pilot study has been carried out to evaluate three aspects of screening of first-degree relatives of patients with colon cancer in four Hamilton hospitals; yield of adenomas, feasibility of a one-visit approach to screening and treatment, and compliance. Protocol included flexible sigmoidoscopy after full bowel preparation, followed immediately by either therapeutic colonoscopy or diagnostic barium enema, depending on the flexible sigmoidoscopy findings. We found adenomas in 19 percent of 88 first-degree relatives, with a mean age of 52, compared with an expectation of 8 percent. The protocol was found to be acceptable to the relatives and workable for the various groups of physicians in three of four hospitals, despite many initial logistic difficulties. Numerous problems were encountered with compliance of referring physicians, index patients, relatives, and investigating physicians.

Mass screening for rectal neoplasm in Jiashan County, China

Jiashan county is a rural area in China with very high incidence and mortality rates of colorectal cancer. From 1980 to 1984, we conducted a mass screening for rectal neoplasm in the 11 people's communes in this county. Of the 72,879 individuals who were eligible for screening, 60,496 participated, representing an overall participation rate of 83.0%. Both the fecal occult blood (OB) test and rectoscopy were performed on 47,560 of the participants, and rectoscopy only was performed on the remaining 12,936 individuals. From the mass screening, 15 rectal cancers, 3 carcinoids, 899 polyps, 98 ulcers, and 7 inflammatory tumors were detected, a total of 1022 cases. Eight of the 15 detected cases of rectal cancer were in Dukes' stage A. We did not find any evidence for an association between schistosomiasis and colorectal cancer. Results from the OB test were found to have a negative correlation with results from rectoscopy (odds ratio = 0.8, 95% CI = 0.6, 1.1). The OB test had a high false positive rate of 32.7%, and a poor positive predictive value of 3.5%. Both its positive and negative predictive powers were below 1.0, in other words, its positive likelihood ratio was below 1.0 and negative likelihood ratio was above 1.0, indicating that the OB test is not informative and has a poor predictive accuracy for rectal neoplasm. In addition, there were a number of practical problems concerning the use of the OB test for mass screening in the rural community.(ABSTRACT TRUNCATED AT 250 WORDS)

The potential and limitations of laser photoablation of colorectal adenomas

Ablation of colorectal adenomas by Nd:YAG laser energy was investigated in 271 patients. Two hundred and forty-one patients, selected because of poor surgical and medical condition or refusal of surgery, presented with incompletely removed polyps or with lesions unsuitable for endoscopic polypectomy. Thirty patients with polyposis coli were treated for rectal stump polyps after subtotal colectomy and ileorectal anastomosis. Because of insufficient follow-up (28) or malignant degeneration (23), full evaluation was possible in 196 colon adenoma and 24 polyposis patients. Complete ablation with histologic confirmation for at least 12 weeks was achieved in 150 (82%) of the 183 colon adenomas. This declined to 141 (77%) because of later recurrences in prolonged follow-up. Treatment of large adenomas was less successful than that of intermediate and small lesions: ultimate ablation in 56, 85, and 93%, respectively. Impressive was the immediate relief in 100 symptomatic elderly patients, who were bothered by frequent diarrhea, excessive mucous discharge, and incontinence. All patients survived despite major complications (7%) that mainly consisted of stenosis and hemorrhage. Rectal stump polyps were eliminated in 20 patients with polyposis coli. The remaining four had an uneventful ileoanal anastomosis for ultimately uncontrollable growth of polyps. Malignancy was discovered in 22 adenoma patients and in 1 polyposis patient. We recommend laser ablation of colorectal adenomas for small and medium-sized polyps, that cannot be removed by endoscopic polypectomy in inoperable patients or in patients refusing operation. Laser treatment for extensive adenomas seems only appropriate for symptomatic relief.

Free radicals and the etiology of colon cancer

This hypothesis paper reviews diverse evidence suggesting that intracolonic production of oxygen radicals may play a role in carcinogenesis. The hypothesis began to evolve when the author made the chance discovery that 1/10,000 dilutions of feces generated detectable quantities of highly reactive hydroxyl radicals (HO.). The rate of HO. formation, detected using DMSO as a molecular probe, was quite remarkable, corresponding to that which would be produced by over 10,000 rads of gamma irradiation per day, absorbed in the periphery of the fecal mass adjacent to the mucosa. The relatively high concentrations of iron in feces, together with the ability of bile pigments to act as iron chelators that support Fenton chemistry, may very well permit efficient HO. generation from superoxide and hydrogen peroxide produced by bacterial metabolism. Such free radical generation in feces could provide a missing link in our understanding of the etiology of colon cancer: the oxidation of procarcinogens either by fecal HO., or by secondary peroxyl radicals (ROO.) to form active carcinogens or mitogenic tumor promotors. Intracolonic free radical formation may explain the high incidence of cancer in the colon and rectum, compared to other regions of the GI tract, as well as the observed correlations of a higher incidence of colon cancer with red meat in the diet, which increases stool iron, and with excessive fat in the diet, which may increase the fecal content of procarcinogens and bile pigments.

Early detection of colorectal cancer by quantitative fluorescence image analysis of exfoliated cells

Early-stage colorectal cancer is potentially curable. In the present study, we applied quantitative fluorescence image analysis (QFIA) cytology to the detection of experimental colorectal cancer in a rodent model. QFIA cytology combines visual cytologic examination with quantitation of DNA content in single exfoliated cells. Cancer was induced by treating 110 rats with subcutaneous 1,2-dimethylhydrazine. Sequential colon washes were obtained weekly from each animal for 20 weeks. Control animals were treated identically except for the administration of carcinogen. Cells that were cytologically abnormal or had increased DNA content were found starting in the second week. By the eighth week, roughly 50 percent of animals had positive results, and this level remained approximately constant for the duration of the study. Tissue pathologic results were normal during weeks 1 to 7. Dysplasias became common during weeks 8 to 15 whereas most cancers appeared during weeks 16 to 21. These results indicate that QFIA cytology is a highly sensitive method for detecting even preneoplastic changes resulting from carcinogen administration and may prove useful in detecting human colorectal cancer.

Polyps of the colon in Barcelona, Spain. An autopsy study

This study is based on a prospective survey of 212 autopsies that was conducted to determine the prevalence of colon adenomas in Barcelona, Spain. Adenomatous polyps were found in 21.7% of the patients (29.3% of the men and 12.5% of the women); multiple adenomas were found in 40% of the patients. Almost all adenomas were less than 5 mm in diameter, although 6.7% of the ones seen predominantly in the rectosigmoid colon were larger than 1 cm. The prevalence and number of adenomas increases with age. The prevalence of hyperplastic polyps was very low (1.6%). The data shows a relationship between the prevalence of colon adenomas in Spain and the incidence of colon cancer. The prevalence of colon adenomas in Spain is one of the lowest compared with that in other European countries and North America.

Effect of workup strategy on the cost-effectiveness of fecal occult blood screening for colorectal cancer

Physicians respond to a positive fecal occult blood test with a variety of workup strategies. To study the effect of the choice of strategy on the net costs and health benefits of colorectal cancer screening using this test, we used a decision analysis model to compare seven strategies that physicians might choose to examine a positive "screenee." Strategies using rigid or flexible sigmoidoscopy alone are not only insensitive, but also have high cost-effectiveness ratios. The strategy of air contrast barium enema alone had the lowest cost-effectiveness ratio. Rigid sigmoidoscopy combined with barium enema had a lower cost-effectiveness ratio than primary colonoscopy, but the strategy of primary colonoscopy could have an equal or better ratio depending on assumptions about test costs and the benefit of removing benign polyps. The primary colonoscopy strategy is both more effective and less costly than the combination of flexible sigmoidoscopy and barium enema. The optimal strategy will vary with local factors, and with the perspective of the decision-maker.

Mass screening for colorectal cancer in Hungary

Haemoccult screening for colorectal tumours was carried out in Hungary in small cities and villages around Budapest. Haemoccult slides were supplied to 17,662 individuals over 40 years of age, and 15,431 (87%) were returned. Of these, 346 (2.2%) were positive and 18 colorectal carcinomas were detected. Additionally, 24 patients with one or more polyps greater than 1 cm diameter were found. Of the screened cases of cancer 39% were in Dukes' stage A and B, a rate twice as good as when screening was not done. The cost per tumour detected amounted to about three times more than one monthly income, indicating that the costs of screening for colorectal cancer are relatively much higher in Hungary than in Western countries. All expenses were met from state funds.

Biochemical markers in patients with familial colonic neoplasia

Many potential markers, including biochemical markers, have been studied in an attempt to identify the presence of early colorectal neoplasia or risk of neoplasia, particularly in those families with hereditary colonic neoplasia syndromes. Unfortunately, most of these markers are useless in screening or diagnosis. Nevertheless, such markers as carcinoembryonic antigen (CEA) and CA 19-9 may have a role in pretherapeutic and posttherapeutic monitoring of disease or recurrence. The newer tumor markers, including the carbohydrate markers, ornithine decarboxylase (ODC) and the polyamines, are of great interest as potential tumor markers; ODC and the polyamines may also have a future potential as therapeutic targets. However, further studies are needed to determine their true sensitivity and specificity in hereditary colonic neoplasia syndromes, as well as in patients without genetic syndromes who are at risk for colorectal cancer.

Colorectal adenomatous polyps and carcinoma in Ashkenazi and non-Ashkenazi Jews in Israel

In Israel, the incidence of colorectal cancer among European-American-born Jews is approximately 2.5 times that of African-Asian-born Jews. To determine the risk of all colorectal tumors for the two ethnic groups, 335 patients with colorectal adenomatous polyps and 295 with colorectal cancer, diagnosed between 1980-1984 at the Sheba Medical Center, were compared to the 35,094 persons attending the outpatient clinics at the same hospital, during September and October 1984. Ashkenazi patients (European-American-born) had a 2.5-fold risk (95% confidence interval 1.9-3.3) of colorectal polyps compared to non-Ashkenazi patients (African-Asian-born). The risk was similar for males (odds ratios [OR] = 2.3) and females (OR = 2.8). Ashkenazis also had a significantly enhanced risk of carcinoma: OR = 3.1; 95% confidence interval 2.2-4.3. The risk ratio was slightly higher for males (OR = 3.5) than females (OR = 2.7). Age-specific analyses demonstrated an elevated risk of both malignant and benign neoplasms among Ashkenazi patients at all ages at diagnosis. Among the polyp patients, the highest risk ratio was for patients between 30 and 49 years old, while among the cancer patients the risk was highest in the group of 60-69-year-olds. The distribution by size of polyps, number of polyps, as well as polyp subsite, was similar for Ashkenazi and non-Ashkenazi patients; however non-Ashkenazis tended to have slightly more right-sided colon cancer.

Laser photocoagulation in the palliation of colorectal malignancies

Besides surgical intervention, there are virtually no palliative treatment modalities available for bleeding and/or obstructing colorectal malignancy. The usefulness and safety of laser photocoagulation was prospectively investigated in 63 patients with colorectal cancer. The merits were evaluated in the treatment of obstruction (16 patients), bleeding (32 patients), and combined hemorrhage and obstruction (15 patients). Luminal patency could be restored in 15 (94%), hemostasis was achieved in 28 (88%), and treatment was effective in 13 (87%) patients with bleeding and obstructing tumors. In the 56 evaluable and initially responding patients, no beneficial long-term results were achieved in six patients, as major complications of (re)stenosis, necessitating colostomy, occurred in three, posttreatment hemorrhage with need for blood transfusion in two, and a pararectal abscess formation was seen in one patient. Except probably for this pararectal abscess, there was no treatment-related death. Transient stenosis and laser-induced bleeding, as minor complications present in 12 (19%), responded favorably upon reinstitution of laser photocoagulation. The beneficial effect of laser photocoagulation was, in general, evident after 2 to 3 sessions. Forty-six patients could be discharged from the hospital and their treatment could be continued in the outpatient clinic. Further hospital admission could be avoided in 39. Laser treatment for palliation of obstructing and/or bleeding colorectal cancer proved to be an efficacious, safe, and rapidly effective therapy. Laser photocoagulation can be considered as a valuable alternative to aggressive surgical intervention in the absence of other conservative treatment modalities in palliation.

Colorectal tumor screening in women with a past history of breast, uterine, or ovarian malignancies

Epidemiologic studies have shown that women who have successfully recovered from breast, uterine, or ovarian cancer have about twice the expected risk of developing colorectal cancer. These high-risk women were entered, therefore, into a large bowel screening program based on fecal occult blood detection, flexible sigmoidoscopy, and colonoscopy, when appropriate. The study group consisted of 183 women and the results were compared with 252 comparison subjects of similar age and ethnic origin. Neoplastic lesions, adenomatous polyps, or cancer were 2.5 times more frequent in the study group. However, for the largest group, women with a past history of breast cancer, the relative risk, adjusted for a family history of gastrointestinal cancer, was 3.0 (P = 0.03). This pilot study confirms the value of continuing to screen these patients, especially those with a positive family history of gastrointestinal malignancies. However, for psychological and administrative reasons, it may be better that their colon screening be integrated into a combined colon, breast, and gynecologic tumor follow-up, and not be part of a separate service.

Fecal skatole and indole and breath methane and hydrogen in patients with large bowel polyps or cancer

The object of this study was to explore the use of fecal skatole and indole and breath methane and hydrogen as metabolic markers of the anaerobic colonic flora in patients with unresected large bowel cancer or polyps. Patients with descending or sigmoid colon cancer were more likely to be breath methane excretors than control subjects, patients with proximal colon cancer, and patients with rectal cancer. Control subjects excreting breath methane excreted less fecal skatole than breath methane excretors in the following groups: patients with adenomatous polyps, all patients with colorectal cancer, patients with proximal colon cancer, patients with descending and sigmoid colon cancer, and patients with rectal cancer. These data suggest that fecal skatole excretion equal to or greater than 100 micrograms/g feces might be useful to discriminate colorectal cancer patients from control subjects. Twenty-nine percent (8 of 28) of the cancer patients had both "high" skatole levels and breath methane excretion compared with only 2% (1 of 41) of the control subjects (P less than 0.01).

Sex differences in the changing anatomic distribution of colorectal carcinoma

The anatomic site distribution of large bowel cancer was studied in 2079 patients between 1967 and 1980. To measure the trend in the localization of the carcinomas, the slope of the regression line of the proportions at each site over the years was computed. The large bowel was divided into five segments: cecum, ascending colon and hepatic flexure, transverse and descending colon, sigmoid and rectosigmoid junction, and rectum. A significant decrease in the proportions of cancer in the sigmoid for both sexes (slope parallel b = -0.89; P less than 0.001) and an increase of cecal cancer (b = 0.54; P less than 0.004) was observed. Sex-specific results indicated the diminishing proportion of sigmoid cancer in men (b = -1.04; P less than 0.004) with an increase in transverse and descending colon cancer proportions (b = 0.52; P = 0.012). In women, a negative slope of -0.74 was not significant for sigmoid cancer, but cancer of the cecum showed an increase in proportions (b = 0.80; P = 0.01). The age distribution indicated a significant decrease in proportion of men older than 80 years and of women in the age group of 40 to 49 years and an increase in women older than 80 years. However, age adjustment did not change any of the previous conclusions. The observed sex differences in the changing distribution within the large bowel over a 14-year period cannot be explained by the improvement of diagnostic tools in the last years. In view of these findings, it is important to evaluate the possible sex-related bias in the application of screening and preventive measures as well as the changes in the ecologic features of the large intestine.

Nutrition and cancer: state of the art relationship of several nutrients to the development of cancer

Nutrition and cancer interact in a number of important ways and nutritional factors are increasingly recognized as relevant to both the prevention and treatment of cancer. The role of several nutrients in cancer development is considered briefly here. Deficiency of riboflavin (Vitamin B2) prolongs the survival of tumor-bearing animals, but may accelerate carcinogenesis caused by certain agents, as flavin cofactors are involved in drug and carcinogen metabolism. Deficiency of Vitamin A may enhance the development of tumors of epithelial origin, particularly lung. Evidence is accumulating that Vitamin A and/or its precursors, the B-carotenes, may possibly have an effect in chemoprevention of certain of these epithelial cancers both in animals and in man. The consumption of dietary fat among various nations is correlated closely with increased development of cancers of the breast, colon, and prostate, and possibly of other organs. Studies of migrant populations from Japan to the United States show changes in prevalence of stomach and colon cancer in the direction of the native United States population. Sources of nitrites are of concern because of their potential conversion to carcinogenic nitrosamines. Limitation of the delivery of nitrites may be difficult to accomplish so investigators are exploring the blockade of conversion of nitrites to nitrosamines. Nutrition should not be viewed as the sole means of cancer prevention and treatment but rather as a vital component of any treatment plan.