Value of retesting subjects with a positive Hemoccult in screening for colorectal cancer

Review of the evidence for a colorectal cancer screening programme in elderly people

Colorectal cancer is a major public health issue, contributing to 16,000 UK deaths per year, most of these in the elderly population. A new NHS screening programme for colorectal cancer in people over 60 is being introduced across the country throughout 2009. The aim of this research was to review the current literature on colorectal cancer screening and determine how much of the evidence for screening is applicable to elderly people. MEDLINE database was searched for articles published between 1990 and 2007, using search terms of colorectal neoplasms, mass-screening, faecal occult blood, colonoscopy and sigmoidoscopy. Articles for inclusion were limited to those in English and those including older adults. The results showed that evidence for colorectal cancer screening in general has been well researched. However, little was found specifically on screening for elderly people, or looking at the different benefits and limitations in older people compared to younger people. Very few health agencies suggested an upper age limit for screening. In conclusion, there is very little research on screening for colorectal cancer specifically in elderly people, although many health authorities advise such screening. The health needs of an older population are different to those of middle-aged people and at present the screening programmes do not appear to reflect this.

Survival benefit in a randomized clinical trial of faecal occult blood screening for colorectal cancer

BACKGROUND

Early detection of colorectal cancer could reduce cancer-specific mortality. The aim of this trial was to evaluate the effect of faecal occult blood test (FOBT) screening on colorectal cancer mortality in a Swedish population.

METHODS

All 68,308 citizens in Göteborg born between 1918 and 1931 were randomized to a screening or a control group at the age of 60-64 years. All were screened two to three times with rehydrated Hemoccult-II. Compliance was 70.0 per cent (23,916 individuals). Those with a positive test result were offered sigmoidoscopy and a double-contrast enema. The primary endpoint was death from colorectal cancer.

RESULTS

After a mean of 9 years from the last screening, there was a significant reduction in colorectal cancer mortality in the screening group compared with the control group. The overall risk ratio of death from colorectal cancer was 0.84 (95 per cent confidence interval 0.71 to 0.99). The groups did not differ in incidence of colorectal cancer or in overall mortality.

CONCLUSION

FOBT screening significantly reduces colorectal cancer mortality.

Fecal occult blood test screening for colorectal cancer

In summary, high-quality scientific studies indicate that the use of the FOBT for colorectal cancer screening has a number of important advantages. The test is capable of detecting most early colorectal cancers and many advanced adenomas. It has been shown in randomized, controlled trials to reduce substantially colorectal cancer mortality and incidence. The FOBT is feasible, widely available, and acceptable to most individuals. It has a low up-front cost and is highly cost-effective. Combining annual FOBT with periodic flexible sigmoidoscopy seems to be an especially effective screening option. Limitations of FOBT screening include its low sensitivity for polyps, especially smaller ones. Some of the trials report a relatively low sensitivity for detecting cancers located in the distal colon. The test has a relatively low specificity, so there are many false-positive screens; and for it to be most effective, repetitive screening is necessary. Balancing these advantages and disadvantages, the evidence-based screening guidelines have concluded that FOBT screening has a major role to play in colorectal cancer control and a program of annual FOBT plus flexible sigmoidoscopy every 5 years is a preferred option for screening the asymptomatic, average-risk population for colorectal cancer. Short of doing direct colonoscopy screening for the entire at-risk population, the FOBT currently is the best available method of identifying asymptomatic, average-risk people most likely to benefit from colonoscopy.

Screening for the major malignancies affecting women: current guidelines

Throughout their lifetimes, many women rely on the obstetrician-gynecologist to provide them with regular health care. Therefore the obstetrician-gynecologist should be able to provide comprehensive information regarding consensus screening recommendations for the major malignancies that occur in women. Additionally, a woman's health care provider should continually refine his or her cancer risk--assessment skills and should remain apprised of high-risk habits, family histories, and other cancer-predisposing factors that allow identification of those women in whom heightened surveillance or intervention may be appropriate. This article reviews the epidemiologic and risk factors associated with the major malignancies that affect women today and provides screening guidelines.

Screening guidelines for colorectal cancer

Evidence-based guidelines recommend that all asymptomatic, average-risk U.S. citizens >50 years of age be encouraged to undergo screening for colorectal cancer. Those at higher risk should be offered more intensive screening and follow-up surveillance. It is estimated that widespread adoption of these recommendations could reduce mortality from colorectal cancer by >50%. The only screening methods that have been evaluated directly are the fecal occult blood test and flexible sigmoidoscopy. Current guidelines now recommend annual screening for fecal occult blood plus flexible sigmoidoscopy every 5 years for asymptomatic, average-risk men and women >50 years of age. Indirect evidence supports the options of colonoscopy or barium enema x-ray screening for highly motivated individuals, but these methods have not yet been tested in prospective trials. In the future, gene-based screening tests may be developed, and computed tomography of the colon ("virtual colonoscopy") may prove effective and feasible.

Fecal occult blood testing for colorectal cancer. Can we afford not to do this?

Current practice guidelines recommend annual fecal occult blood test screening for colorectal cancer in the average-risk population over the age of 50. Efficacy of fecal occult blood test screening is supported by several controlled prospective trials and case-control studies. Implementation of this recommendation, in combination with periodic flexible sigmoidoscopy every 5 years, is feasible, affordable, highly effective, and has the potential for reducing colorectal cancer mortality by at least 50%. With over 50,000 Americans dying of this malignancy each year, we cannot afford not to do this.

Colorectal cancer screening

The decision whether to launch a screening program in asymptomatic patients of average risk for colorectal cancer and the selection of the appropriate protocol for screening are complex issues. There are still many unanswered questions. Many organizations such as the American Cancer Society, the World Health Organization Collaborating Center for the Prevention of Colorectal Cancer, and the U.S. National Cancer Institute advocate screening with annual Hemoccult tests and screening with flexible sigmoidoscopy every 3 to 5 years in patients more than 50 years of age. The U.S. Preventive Services Task Force, the Canadian Task Force on Periodic Health Examination, and the International Union Against Cancer have not recommended screening asymptomatic average-risk patients for colorectal cancer. One study showed a small but significant benefit (3 per 1000) of the rehydrated annual Hemoccult test in reducing mortality from colorectal cancer. To embark on a mass screening strategy as recommended, however, would require significant costs, increases in physician training, improved access to the requisite technology, and enhancements in patient and physician compliance. Furthermore, the high false-positive rates of the rehydrated Hemoccult tests would lead to many unnecessary tests, causing greater expense as well as patient discomfort and anxiety. It is, therefore, premature to recommend mass screening for colorectal cancer in asymptomatic individuals at this time. Further research is needed to identify risk factors (such as genetic markers) better and to develop and evaluate screening strategies targeted at those with high risk for colorectal cancer. In the meantime, efforts at primary prevention for the general population should be increased (through nutrition and exercise). Patients over the age of 50 who desire screening should be given information of the benefits and risks of screening and together with their physicians decide on a screening strategy that suits their needs and values.

Results of screening, rescreening, and follow-up in a prospective randomized study for detection of colorectal cancer by fecal occult blood testing. Results for 68,308 subjects

All 68,308 inhabitants of Göteborg born between 1918 and 1931 were randomly divided into a test and a control group. The subjects in the test group were invited to perform Hemoccult II fecal occult blood testing on 3 days and to repeat the test after 16 to 24 months. In the prevalence screening 21,347 (63%) performed the test, and in the rescreening 19,991 (60%). Investigation of the 942 (4.4%) with positive tests in the prevalence screening showed 47 cancers and 129 subjects with adenomas > or = 1.0 cm. In the rescreening 5.1% had a positive test, and 34 cancers and 122 subjects with adenomas (> or = 1.0 cm) were found among those. Cancer had also been diagnosed in 19 subjects in the interval between the two screening occasions and in 15 subjects among the non-responders. Forty-four cancers had been diagnosed in the control group during the same period. Cancers detected by screening were at a less advanced stage than in the control group. It is too early to show any effect of screening on mortality from colorectal cancer.

The correlation of symptoms, occult blood tests, and neoplasms in patients referred for double-contrast barium enema

One hundred and forty-nine patients (86 women) with a mean age of 64 years (52-74 years), referred for double-contrast barium enema (DCE), were invited to have fecal occult blood test and rectosigmoidoscopy (60 cm) (RSS) before the DCE. Carbon dioxide was used for inflation at RSS to enable the two examinations to be done at the same time. Eight adenomas < 1.0 cm in diameter, 11 adenomas > or = 1.0 cm in diameter, and 5 carcinomas were diagnosed in altogether 23 patients. There was no correlation between symptoms, diverticula, or neoplasm, but a positive rehydrated Hemoccult II test was correlated to the presence of neoplasms (cancer and adenoma > or = 1.0 cm in diameter), but Hemoccult is not suitable as selection basis for work-up of symptomatic subjects. To diagnose colorectal neoplasms, we have to accept a certain number of negative work-ups of the large bowel. If DCE is chosen for work-up of the large bowel, it has to be combined with rectosigmoidoscopy (60 cm).