Selection of colon cancer patients for neoadjuvant chemotherapy by preoperative CT scan

Preoperative staging is essential to plan correct treatment of colon cancer and calls for objective, accurate methods for the introduction of neoadjuvant chemotherapy, which represents a new treatment option.

To evaluate the diagnostic accuracy of multislice computed tomography (CT) in local staging of colon cancer correlated with histopathological parameters, including criteria for adjuvant chemotherapy.

A total of 74 included patients had preoperative CT scans and surgical resection of their colon tumors. Tumor stage (T-stage), extramural tumor invasion (ETI), nodal stage (N-stage), extramural venous invasion (EVI) and the distance from tumor to nearest retroperitoneal fascia (DRF) were retrospectively assessed on the CT scan and compared blindly with the results of the pathological examination, including evaluation of the criteria for adjuvant chemotherapy. Advanced tumors were defined as T3 with ETI ≥5 mm or T4.

Sixty-nine percent of the tumors were correctly T-staged by CT, 7% were overstaged and 24% were understaged. As to correct recognition of ETI on the CT scan, the observer was 73% accurate compared with histology (70% sensitivity (95% CI: 53-82%), 78% specificity (95% CI: 60-90%), 81% positive predictive value (PPV) (95% CI: 63-91%) and 66% negative predictive value (NPV) (95% CI: 49-80%). N-stage, EVI and DRF had poor accuracy: 53%, 53% and 64%. All patients with advanced tumors on CT fulfilled the criteria for adjuvant chemotherapy. Positive predictive value: 100% (95% CI: 88-100%).

CT has a potential in the preoperative selection of advanced tumors suitable for neoadjuvant chemotherapy without overtreatment of low-risk patients.