Predictive value of common symptom combinations in diagnosing colorectal cancer

Background: This study compared the diagnostic values of age and single symptoms of colorectal cancer with those of age and symptom combinations. Methods. Consecutive patients with lower gastrointestinal symptoms referred to a surgical clinic over a 12-year period were studied prospectively. The diagnostic value of age and common symptoms of bowel cancer, individually and in combination, was determined by measuring positive predictive value, sensitivity and specificity. Results: In total, 467 (5.5 per cent) of 8529 patients had colorectal cancer. Symptom combination analyses showed that patients presenting with rectal bleeding and change in bowel habit without anal symptoms had the highest risk of cancer. Those with rectal bleeding and perianal symptoms without change in bowel habit were at the lowest risk of having cancer. Symptom subgroups defined by age had positive predictive values for cancer that varied from less than 1 to 35 per cent. Conclusion: Symptom combinations defined by age have greater diagnostic value than single symptoms alone.