Colorectal cancer detection in the practice setting. Impact of fecal blood testing.

To assess the contribution of fecal blood testing to cancer detection in a clinical practice setting, we studied records from 160 patients with both a new tissue diagnosis of colorectal adenocarcinoma and a preceding stool blood test (HemoQuant, Mayo Medical Laboratories, Rochester, Minn) determination. In this group, 71% had suggestive colorectal symptoms (particularly stool changes, overt bleeding, and abdominal pain) or anemia at presentation, and 29% were asymptomatic. Fecal blood levels remained normal in more than 40% of both symptomatic and asymptomatic patients. In only 26 patients (16% overall) was an abnormal fecal blood level the sole heralding feature, but this subset of patients had a more favorable stage. Fecal blood levels were higher with advanced, larger, and more proximal tumors and with stools collected before purgation. We conclude that, in the practice setting, fecal blood level elevation alone is an uncommon but important manner of colorectal cancer presentation, most cancers present with symptoms, and fecal blood levels are often normal in both symptomatic and asymptomatic patients.