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Colorectal cancer is a significant cause of morbidity and mortality in all industrialized nations. Efforts to reduce mortality by early detection through mass screening have met with limited success, despite several large trials involving over 250,000 people. No reduction in mortality has been proved in groups of patients assigned to colorectal cancer screening. Success rates might improve if screening were directed specifically to the segment of the population known to be at increased risk for colorectal cancer. If this is to be effective, a clear understanding of what constitutes a risk factor for this disease is needed. It is often assumed that cancer family syndrome, a heritable condition in which close relatives share an increased risk for developing certain types of cancer, is a powerful risk factor. Cancer family syndrome is somewhat loosely defined, and very few attempts have been made to characterize the prevalence in defined populations. To remedy this situation, an epidemiological study was carried out in Northern Ireland in which the incidence of cancer among 1,811 first-degree relatives of 205 colorectal cancer patients was determined. Cancer family syndrome was defined as the presence of three or more relatives affected by colorectal cancer. Using this criterion, the prevalence of cancer family syndrome was estimated to be between 1 and 2 percent, much less than had been generally assumed. These results have implications for population screening, and indicate that more research is necessary before an effective screening program for colorectal cancer based on known risk factors can be developed. (Consumer Summary produced by Reliance Medical Information, Inc.)

There is extensive interest in improving methods for predicting survival rates in populations of patients suffering from different types of colorectal cancer. It has been reported that there may be different survival rates for patients with hereditary tumors; the so-called cancer family syndrome (the occurrence of similar cancers in numerous first-degree relatives) may be predictive of prolonged survival compared with patients suffering from sporadic (non-familial) tumors. To determine whether the prognosis differed for patients with familial colorectal cancer compared with non-familial, a study was done in which the records of 205 patients under the age of 55 with confirmed colorectal cancer were evaluated. The family histories and causes of death were verified for virtually all the first-degree relatives of these patients. The strength of the influence of family history was assessed using a derived score that took into account death from colorectal cancer within a given family and compared this with the average population mortality. Using this index, family history was not predictive of survival rate either in a univariate analysis or in a multivariate analysis in which age, sex, stage and site of cancer, and duration of symptoms were controlled. Hence, family history does not appear to be an important predictor of survival among patients with colorectal cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)