Early detection of lower GI tract tumors by dedicated assessment of the colon on routine computed tomography (CT) imaging: An observational study.

510 Background: We have previously reported that up to 48% of the early features of colorectal cancer (subtle wall thickening, pericolonic stranding, and small lymph nodes in the draining nodal station) were not identified on the original CT abdomen and pelvis (CTAP) reports. This resulted in a 36% decrease in five-year survival based on historical data. In this report, we assessed whether dedicated assessment of the colon on routine CT scans could lead to early detection of colorectal cancer. Methods: 210 CTAPs over a three-month period were screened from the emergency room records at a tertiary care hospital. 194 scans met eligibility. Exclusion criteria included: cases known to the evaluating radiologist and age ≤ 19 or > 89 years. No study was excluded for suboptimal image quality. The original report was reviewed for abnormalities involving the colon, mesentery and bowel and was recorded. A blinded evaluation of the eligible case was then performed by a board-certified radiologist with attention specifically to the colon and the mesentery for the suspicious early features of CRC. The concordance and discordance was then tabulated. Discordant findings were re-evaluated to determine if the discordance was true. Results: 72/194 patients were male, median age 44.5 years (range 20 - 89). 55/194 patients (29.1%) included in the study were noted to have suspicious features. 26 had abnormal lymph nodes, 24 had abnormal colonic wall thickening and 16 had pericolonic stranding and/or wall edema. 45/55 studies were truly discordant from the original interpretation. These included one missed colorectal cancer (confirmed), one likely small bowel neuroendocrine tumor (no follow up), and one likely transitional cell carcinoma of the right renal pelvis (no follow up). Conclusions: Dedicated search of the colon and mesentery on CTAP can identify subtle findings, although their true relevance is being evaluated in a larger future study. Our observational data does indicate that there maybe a potential role for a focused evaluation of the colon and mesentery on routine CTAP in an attempt to potentially increase the rate of cancer detection especially in younger low-average risk patients.