Background:

Rectal cancer remains a significant clinical challenge with demand for conclusive biomarkers, essential in prognostication and therapy monitoring of neoadjuvant and adjuvant treatment strategies.

Aims:

The aim of the study was to evaluate AXL and cellular mesenchymal-epithelial transition factor (C-MET) biomarkers for cancer stem cells and to correlate them with clinicopathological characteristics and patient outcome data with respect to neoadjuvant chemoradiotherapy.

Methods:

Serum levels of soluble surface markers AXL and C-MET were retrospectively analyzed in 164 rectal cancer patients with additional immunofluorescent analyses of their primary tumor tissues.

Results:

Kaplan-Meier analysis confirmed the prognostic significance of Union for International Cancer Control stages, but with no significant correlation between investigated markers with patient age, gender, or tumor stage. In contrast, tumor tissues demonstrated stage-dependently increased marker expression. While AXL was detected at low levels, C-MET exhibited a bimodal distribution, with elevated levels seen in most patients, particularly post-neoadjuvant therapy and non-significantly in the subgroup with poorer response to neoadjuvant therapy (p=0.074).

Conclusions:

AXL serum levels in the rectal cancer cohort were significantly different from healthy subjects but did not correlate with tumor stage or survival during and after neoadjuvant/adjuvant therapy. Soluble C-MET levels in the blood, influenced by neoadjuvant chemoradiotherapy, may serve as a predictive marker for treatment response.