THE INTRA-TUMOR STROMA MICROENVIRONMENT IN THERAPY MANAGEMENT FOR COLON CANCER PATIENTS

ABSTRACT There is need to identify patients with colon cancer who benefit treatment. We previously have found that the stroma-tissue surrounding cancer cells plays an important role in tumor behavior and is reported as an independent prognostic parameter. Patients with a high stroma percentage within the primary tumor have a poor prognosis. Validation of the parameter was performed in the VICTOR trial. Recently the stroma percentage in lymph nodes and metastases was found a heterogenous process. Moreover the stroma groups respond differently to chemotherapy regimens. Methods Tissue samples consisting of 5 µm Haematoxylin and Eosin (H&E) stained sections from the most invasive part of the primary tumor were analyzed for their tumor-stroma percentage. Stroma-high (>50% stroma) and stroma-low (≤50% stroma) groups were evaluated with respect to survival time and response to therapy. For patients with and without adjuvant therapy (CT) (n = 150) the primary tumor (PT) lymph nodes (LN) and liver metastases were analyzed. Findings What is the profit of additional LN analysis? The CT treated stroma-low patient group showed an improved survival (5-yr OS 75% vs 83%, DFS 76% vs 83%, TTR 84% vs 100%). In the stroma-high patient group we did not notice any improvement of survival (5-yr OS 77% vs. 72%, DFS 68% vs. 68%, TTR 81% vs. 77%). Which stroma group responds better to therapy? The stroma-high group showed a better response to therapy compared to the stroma-low group (increase 5-yr OS 22% vs. 8%, DFS 18% vs. 8%, TTR 21% vs. 13%). Interpretation The intra-tumor stroma percentage has proven to be a prognostic factor. It supports selective treatment for stroma-high and stroma-low patients. Preliminary results show that adjuvant therapy is more efficient for patients with a high stroma percentage. Disclosure All authors have declared no conflicts of interest.