Colorectal and Extracolonic Cancers Detected at Screening CT Colonography in 10 286 Asymptomatic Adults

Purpose: To retrospectively determine the detection rates, clinical stages, and short-term patient survival for all unsuspected cancers identified at screening computed tomographic (CT) colonography, including both colorectal carcinoma (CRC) and extracolonic malignancies. Materials and Methods: From April 2004 through March 2008, prospective colorectal and extracolonic interpretation was performed in 10 286 outpatient adults (5388 men, 4898 women; mean age, 59.8 years) undergoing screening CT colonography at two centers in this institutional review board-approved, HIPAA-compliant study. For all histologically proved, clinically unsuspected cancers detected at CT colonography that were identified at retrospective review of the medical records, the stage of disease, treatment, and clinical outcome were analyzed. Benign neoplasms (including advanced colorectal adenomas), symptomatic lesions, and tumors without pathologic proof were excluded. Statistical analysis was performed with Fisher exact test and two-sample z test. Results: Unsuspected cancer was confirmed in 58 (0.56%) patients (33 women, 25 men; mean age, 60.8 years), which included invasive CRC in 22 patients (0.21%) and extracolonic cancer in 36 patients (0.35%). Extracolonic malignancies included renal cell carcinoma (n = 11), lung cancer (n = 8), non-Hodgkin lymphoma (n = 6), and a variety of other tumors (n = 11). Cancers in 31 patients (53.4%) were stage I or localized. At the most recent clinical follow-up (mean, 30.0 months +/- 11.8 [standard deviation]; range, 12-56 months), three patients (5.2%) had died of their cancer. Conclusion: The overall detection rate of unsuspected cancer is approximately one per 200 asymptomatic adults undergoing routine screening CT colonography, including about one invasive CRC per 500 cases and one extracolonic cancer per 300 cases. Detection and treatment at an early presymptomatic stage may have contributed to the favorable outcome. (C) RSNA, 2010