Response Prediction in Metastasized Colorectal Cancer Using Intratumoral Thymidylate Synthase

Eligible were patients with non-resectable metastasized or recurrent histologically proven CRC with the presence of a reference lesion two-dimensional measurable and accessible for a biopsy.The biopsy was taken from the reference lesion either by surgery during primary tumor resection, by trans-cutaneous true-cut needle biopsy or by trans-anal approach. Intratumoral relative TS mRNA expression levels were determined using samples shipped in RNA-preserving solution or as glass slides after microdissection of tumor cells. An independent company stratified the patients according to ther relative TS mRNA expression level in TS low and TS high followed by randomization to receive either FUFA of Folfiri. Response to chemotherapy was evaluated and documented according to the RECIST criteria after every therapy cycle.