Assessing the role of CT imaging in identifying candidates for neoadjuvant chemotherapy in right colon cancer: a critical analysis

TL;DR

This study evaluates how well CT scans can identify right colon cancer patients suitable for neoadjuvant chemotherapy, finding that CT scans may lead to unnecessary treatment.

Contribution

The study provides new evidence on the limitations of CT imaging in accurately staging right colon cancer for neoadjuvant chemotherapy decisions.

Findings

CT scans showed low sensitivity (26%) for detecting pT4b tumors but high specificity (91%).

CT had high nodal disease sensitivity (87%) but low specificity (41%).

43% of patients selected for neoadjuvant chemotherapy based on CT findings may have been overtreated.

Abstract

Standard treatment for localized right colon cancer is radical surgery, followed by adjuvant chemotherapy for stage III or intermediate MSS and high-risk stage II tumours. Recent studies suggest a benefit from neoadjuvant chemotherapy (NAC), particularly for T4b and/or N + tumours. Patient selection for NAC relies on CT-based clinical staging, but the accuracy of CT in detecting high-risk features is variable, raising concerns about potential overtreatment. The study aims to demonstrate the accuracy of CT staging of the right colon with the purpose of indicating neoadjuvant CT.

Patients undergoing curative right hemicolectomy between 2013 and 2023 at two Portuguese institutions were included. All had preoperative CT; those receiving NAC were excluded. Sensitivity, specificity, positive predictive value, and negative predictive value of CT in identifying T4b and N + tumours were calculated by comparing clinical (cTNM) and pathological (pTNM) staging.

Among 165 patients (48% male, mean age 70.5 years), CT showed low sensitivity (26%) but high specificity (91%) for pT4b tumours, with a tendency toward understaging. For nodal disease, sensitivity was 87% and specificity 41%. Only 57% of cT4b and/or cN + cases confirmed at least one unfavorable pathological factor, implying potential overtreatment in 43% of patients if NAC were applied solely based on CT findings.

CT remains the standard for clinical staging but demonstrates limited accuracy in identifying high-risk right colon cancers. NAC decisions should integrate additional criteria beyond CT findings to avoid overtreatment.

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