Colorectal cancer in Östergötland : risk factors, diagnosis, and quality of treatment

Abstract: In this investigation colorectal cancer in the county of Östergötland has been studied with emphasis on risk factors, diagnostic efforts, and the results of treatment.In two case-control studies on food and colorectal cancer, a decreased risk was associated with a high intake of cereal fibre, total fibre, and calcium per unit energy consumed as well as a high intake of raw vegetables. Processed meat was associated with an increased lisk for colon cancer and alcohol with an increased risk for rectal cancer. Drug consumption was also found to influence the cancer risk.In a case-control study on occupational factors and the risk for colorectal cancer, some occupations seemed to influence the risk for colon and rectal cancer in different ways. Twenty years of physically active work significantly decreased the risk for left-sided colon cancer but increased the risk for rectal cancer. Accordingly, twenty year of sedentary work significantly decreased the risk for rectal cancer.Known risk factors were found in 12% of colorectal cancer patients, though previous cholecystectomy did not turn out to be a risk factor.The symptoms of colon cancer are vague and unspecific, whereas bleeding is prominent and a dominating symptom in rectal cancer. Conflicting results have been presented regarding the importance of a short delay between onset of symptoms and treatment. In our study, a more favourable stage distribution was found for rectal cancer with a very short delay between start of symptoms and treatment, but not for colon cancer.Results of treatment for colorectal cancer show considerable variation in different series, which can be due to differences in selection and classification as well as in treatment. A computerized system for quality assurance of colorectal cancer was introduced in Östergötland in 1984. All cases diagnosed 1984-1986 were registered in this system, making it possible to study outcome of treatment for an unselected population. The results of treatment in terms of postoperative mortality and five year survival were comparable to the results from specialised international centres, but local recunence rate after operation for rectal cancer was high (20%).To reduce this local recurrence rate, the technique of total mesorectal excision was introduced in three of the surgical departments in the county. Using the system for quality assurance, the local recunence rate during a three year period before the change in technique was compared with a three year period when the new technique was used. The local recunence rate was significantly reduced in the later period without any change in postoperative complications.In conclusion this study shows an environmental influence on cancer-risk that may be different for colon and rectal cancer. The usefulness of a continuous quality assurance system to detect shmtcomings in diagnosis and treatment and to evaluate new techniques is also shown. Finally, total mesorectal excision reduces the local recurrence rate for rectal cancer in an unselected population treated in different kinds of hospital.