Capabilities of computed tomography in the preoperative assessment of peritoneal carcinomatosis in patients with colorectal cancer

Objective. To study the diagnostic effectiveness of CT in the preoperative assessment of the peritoneal carcinomatosis index (IPC) in patients with colon cancer in comparison with diagnostic laparoscopy (DL) and surgical revision with histological examination. Material and methods. The data of 40 patients with colorectal cancer (CRC) and verified peritoneal metastases treated at the Kaluga Regional Clinical Oncological Dispensary in 2019—2023 were retrospectively analyzed. The average age was 64.5±18.8 years; 21 women (52.5%), 19 men (47.5%). The CT and DL results were compared with the data of surgical revision and histology using the criteria of c2 Pearson, Mann–Whitney and post-hoc analysis. Results. The effectiveness of DL in the assessment of carcinomatosis was higher than CT: sensitivity — 96.4% versus 75.1%, specificity — 83.0% versus 81.3%, diagnostic significance of a positive result — 95.0% versus 73.0%, diagnostic significance of a negative result — 87.3% versus 82.9%. The AUC for DL and CT was 0.897 and 0.794, respectively. According to the post-hoc analysis, the consistency of CT with histology was maximal in the regions 0, 2, 5, 6, 7, 10 (up to 92.31%) and the minimum in the regions 1, 11, 12 (43.59—54.10%). DL showed consistently high agreement (74.36—97.44% in regions 0, 5, 7, 9), outperforming CT in the small bowel region (zones 9—12). Conclusion. CT does not reliably exclude peritoneal carcinomatosis in CRC due to the high frequency of false negative results for small (<0.5 cm) metastases in the small intestine. Therefore, the main role of CT is shifting from the “screening” exclusion of peritoneal carcinomatosis to the confirmation of extraabdominal metastases, which affects the choice of treatment tactics and the prevention of unjustified laparotomies.