Serum iron and ferritin levels in patients with colorectal cancer in relation to the size, site, and disease stage of cancer.

We investigated blood loss from colorectal cancer in 92 men seen between January 1990 and June 1997, in relation to the size and site of the tumor, Dukes stage, pathologic type of cancer, and serum carcinoembryonic antigen (CEA) positivity. We used indirect methods, measuring serum hemoglobin, iron, and ferritin concentrations. The means of these three concentrations were significantly lower in patients with a tumor >3cm than in those with a tumor < or =3cm in largest diameter. The means of the three values were lower in patients with proximal colon cancer than in those with distal colon cancer, but only the difference in serum hemoglobin concentration was significant. Cancers of the ulcerative type were found more often in the proximal colon. The proportion of patients with Dukes stage C or D was not different between those with proximal colon cancer and those with distal colon cancer. There was a positive correlation between tumor size and Dukes stage. There were no differences in serum hemoglobin, iron, and ferritin concentrations with respect to the pathologic type of cancer and CEA positivity. These findings show that blood loss from colorectal cancer is closely related to the size and site of the tumor.