Characteristics of colon cancer at time of presentation

To evaluate the relationships between demographic and clinical characteristics and the stage and site of colon cancer at the time of presentation.

New cases of colon cancer identified through a tumor registry at a teaching hospital during 1989 were reviewed retrospectively. Of the 110 cases, 53% of the subjects were female, 95% were white, and 63% were more than 70 years of age.

Early stages of colon cancer (Dukes A [11%] or B [41%]) occurred in 52%, and late stages (Dukes C [26%] or D [22%]) in 48%. Most patients (88%) presented with symptoms; 12% of the cases were detected in asymptomatic patients. Of the 13 asymptomatic patients, 7 were identified by positive occult blood in the stool, 5 by colonoscopy, and 1 during a hysterectomy. The stage of colon cancer was more likely to be early in asymptomatic patients (85% Dukes A or B) compared to those with symptoms (47% Dukes A or B) (p < 0.02). Sixty-two percent (62%) of the cecum/ascending colon cancer were early compared to 46% of the cancers in other locations (p = 0.11). Seventy-seven percent (77%) of the asymptomatic cancers were located in the cecum/ascending colon compared to 33% of the symptomatic patients (p < 0.02). Age and gender were not associated with site or stage of colon cancer.

The majority of patients with colon cancer are diagnosed when symptomatic. When colon cancer is diagnosed while still asymptomatic, it is more likely to be at an early stage. The most common screening procedure leading to diagnosis in asymptomatic patients is the identification of fecal occult blood. Colon cancer is more likely to be located in the cecum/ascending colon when diagnosed at an asymptomatic stage.