Response Prediction of Chemoradiotherapy for Rectal Cancer Using Rapid Semi-Automated Flow Cytometry.

Area of Science:

• Oncology
• Cell Biology
• Medical Diagnostics

Background:

• Chemoradiotherapy (CRT) effectiveness for rectal cancer is highly variable.
• No reliable biomarkers currently exist to predict patient response to CRT.
• Investigating cell cycle analysis as a potential predictive tool.

Purpose of the Study:

• To determine if cell cycle analysis using flow cytometry can predict CRT effectiveness in rectal cancer.
• To correlate cell cycle phase proportions with treatment response.
• To identify potential biomarkers for rectal cancer treatment outcomes.

Main Methods:

• Prospective study of 32 rectal cancer patients undergoing CRT.
• Rapid, semi-automated flow cytometry (Celltac PEAK) for cell cycle analysis of pre-treatment biopsy specimens.
• Comparison of cell cycle phase proportions with post-CRT tumor reduction (CT) and metabolic activity (FDG uptake).

Main Results:

• Patients with ≥30% tumor reduction showed a significantly higher proportion of cells in the G2/M phase (median 2.45% vs. 0.95%, p=0.022).
• Tumors with complete FDG uptake disappearance after CRT had a higher G2/M phase proportion (median 4.05% vs. 1.24%, p=0.024).
• A high proportion of cells in the G2/M phase was associated with better treatment response.

Conclusions:

• A high proportion of cells in the G2/M phase is a potential biomarker for predicting tumor shrinkage in rectal cancer CRT.
• Cell cycle analysis offers a promising method for personalized treatment strategies.
• Further validation is needed to establish this biomarker in clinical practice.