Tumor Tissue Biopsy for Thymidylate Synthase Expression in Patients with Colorectal Cancer, Ancillary

Pts. must be planning on registering to & be eligible for the above listed studies. Pts. who have been previously registered to any of the above studies and have tumor tissue which has been banked frozen at -80 degrees C or have an available paraffin block of the tumor are eligible. Prior to registration, pts. must have either adequate samples (10 mg) of fresh frozen tissue for RT-PCR analysis or an available paraffin block from which slides can be made for MOAB IHC staining for TS. If the pt is registered on SWOG-9420, the fresh-frozen specimen or paraffin block must come from the meas lesion. If the pt is registered on an adjuv trial, the fresh-frozen tissue or paraffin block must come from the primary tumor and/or draining lymph nodes w/ tumor which has been resected en bloc.