Biomarkers for the early detection of relapses in metastatic colorectal cancers.

PURPOSE To assess prognostic/predictive value of carcinoembryonic antigen (CEA), transthyretin (TRT), αenolase (NNE), β2-microglobulin (β2-micro), B-cell activating factor (BAFF) and circulating tumor cells (CTCs) in metastatic colorectal cancer (mCRC) patients treated with chemotherapy with or without bevacizumab. METHODS 72 histologically confirmed mCRC patients treated at Oncology Institute Cluj were included. Biomarker levels were measured through validated methods. A manual method was used for CTCs, involving hemolysis, cytospin centrifugation and immunocytochemical staining for pan-cytokeratin. Statistical endpoints were response, progression- free survival (PFS) and overall survival (OS). RESULTS Initial chemotherapy was fluoropyrimidine/oxaliplatin-based in 93.1%; bevacizumab was added in 58.3% of the patients. Median PFS and OS were 16.4 and 24.4 months. Two-year OS for CR & PR vs SD vs PD were 90% vs 48% vs 12%, respectively (p<0.01). Two-year OS for chemo/ bevacizumab vs chemotherapy: 65% vs 42% (p=0.09). Baseline CEA ≥5 ng/ml had a negative prognostic impact on OS and PFS (p<0.01). High baseline CEA was predictive of improved OS when adding bevacizumab (2-year OS chemo/bevacizumab vs chemo: 60% vs 17%, p<0.01); adding bevacizumab in patients with normal CEA did not improve OS (p=0.29). Higher than cut-off values for TRT had a positive OS prognostic value (p<0.01); higher levels for NNE, β2-microglobulin and BAFF had a negative impact (p<0.01). Two-year OS for baseline <1 CTC/ml vs ≥1 CTC/ ml was 74% vs 64% respectively (p=0.15). CONCLUSIONS The evaluated biomarkers could be useful prognostic factors for survival. Baseline CEA also has predictive value, suggesting that patients with low levels do not benefit from bevacizumab. A non-statistically significant correlation was observed between the number of CTCs and outcome.