The value of a complete blood count in predicting cancer of the colon

Mortality from colon cancer could be reduced with routine screening, yet screening rates are low. Current screening tools are limited by expense and suboptimal acceptance. A retrospective case–control study of all cases of colon cancer diagnosed at our institution over a 5-year period was performed to determine the frequency of blood count abnormalities in these patients upon presentation. One hundred twenty-seven patients had right-sided colon cancer: 107 (84%) had an elevated red cell distribution width (RDW); 87 (69%) had anemia; and 70 (55%) had a low mean corpuscular volume (MCV). Ninety-eight patients had left-sided colon cancer: 49 (50%) had an elevated red cell distribution width; 43 (44%) had anemia; and 22 (22%) had a low mean corpuscular volume. The red cell distribution width was 84% sensitive and 88% specific for right-sided colon cancer. An elevated red cell distribution width may help better identify those patients who should be referred for full colonoscopy.