Anatomical Distribution of Colorectal Cancer in a Veterans Affairs Medical Center

Objectives: The incidence of sporadic colorectal cancer (CRC) among individuals younger than 50 years of age and the incidence of proximal cancers has varied based on demographic factors in previous studies, and multisociety screening guidelines advise various modalities for average-risk individuals beginning at age 50. We studied the incidence and anatomic distribution of CRC in a population of military veterans to determine whether screening at a younger age is warranted. Methods: In a retrospective review of the electronic medical records of patients diagnosed as having CRC at the Dayton Veterans Affairs Medical Center between 2000 and 2010, a descriptive analysis of age at diagnosis, race, indication for colonoscopy, and anatomical distribution of the tumor was performed. Results: A total of 280 patients with CRC were identified, 272 of whom were histologically confirmed as having adenocarcinoma. The majority (98.6%) were men, with 25.6% of them African American. The mean age at diagnosis was 68.9 years (range 41-89 years), with 35% diagnosed in the eighth decade of life. Only 8 patients (2.9%) were younger than age 50. Most tumors (55%) were located distal to the splenic flexure, with synchronous lesions identified in seven patients. Screening colonoscopy identified only 18 (3.6%) cases. Conclusions: Sporadic colorectal adenocarcinoma in patients younger than age 50 was identified in only 2.9% of all cases, whereas 42.5% of all cases were located proximal to the splenic flexure. This reinforces the American College of Gastroenterology guideline recommendation to initiate CRC screening in average-risk individuals at age 50. This study supports optical colonoscopy as the preferred screening modality.