Can we optimize CEA as a response marker in rectal cancer?

Area of Science:

• Oncology
• Biomarkers
• Gastrointestinal Cancer Research

Background:

• Carcinoembryonic antigen (CEA) is a colorectal cancer biomarker with controversial prognostic value.
• Locally produced CEA shows higher prognostic value than serum CEA.
• The prognostic significance of the CEA/tumor size ratio (CEA/ExT) in rectal adenocarcinoma (ADC) remains under investigation.

Purpose of the Study:

• To investigate the association between the pre-treatment CEA/tumor size ratio (CEA/ExT) and pathological tumor response in rectal ADC patients.
• To evaluate CEA/ExT as a potential predictor of treatment response following neoadjuvant chemoradiotherapy (N-CRT) and surgery.

Main Methods:

• Retrospective analysis of 89 rectal ADC patients treated with N-CRT and surgery (March 2012 - October 2017).
• Calculation of pre-treatment CEA/ExT using CEA levels and tumor extension.
• Analysis of pathological response in surgical specimens post-N-CRT.

Main Results:

• 41.6% of patients showed a good response to N-CRT, with 83.1% experiencing tumor downstaging and 23.6% achieving complete pathological response.
• Higher pre-treatment CEA/ExT values were associated with lower rates of pathological response (p=0.04) and tumor downstaging (p=0.02).
• Multivariate analysis confirmed CEA/ExT as an independent predictor of tumor downstaging (OR: 0.72; 95% CI: 0.53-0.98, p=0.036).

Conclusions:

• Lower pre-treatment CEA/ExT values are linked to improved tumor downstaging in rectal ADC patients.
• The CEA/ExT ratio shows promise as a predictive biomarker for favorable treatment response in rectal ADC patients undergoing N-CRT.