Background: An 18-gene expression profile, ColoPrint, has been developed for identifying CC patients more likely to develop recurrent disease and who would be candidates for adjuvant chemotherapy. The gene signature has been validated in independent cohorts of 206 CC patients and in in-silico datasets (Salazar et al, JCO 2010). The profile classified 63.2% of the stage II patients (n=134) as Low Risk. The Hazard Ratio for relapse free survival (RFS) was 3.34 (p=0.017) with a 5-year RFS rate of 91% (95%CI, 84-98%) for Low Risk patients and 74% (95%CI, 59-89%) for High Risk patients. Moreover, the profile stratified patients independent of ASCO clinical risk factors. Methods: A prospective trial, PARSC (Prospective study for the Assessment of Recurrence risk in Stage II CC patients) using ColoPrint has been initiated. The main objectives are: Determine risk assessment by ColoPrint profile versus clinical parameters based on local protocol and ASCO high-risk recommendations in stage II patients Establish proportion of "good prognosis" and "poor prognosis profile" in various countries Validate the power of risk assessment and compare performance of ColoPrint and clinical risk assessment in estimating 3 year relapse rate. Inclusion criteria: age ≥ 18 years, adenocarcinoma of the colon, stage II, any neo-adjuvant therapy, no synchronous tumors, fresh tumor sample, and written informed consent. The treatment of the patient is at the discretion of the physician but should include a regimen containing a fluorinated pyrimidine. Results: The trial started in Sept. 2008 with currently 26 participating sites in 11 countries. Thus far, 262 stage 2 patients have been enrolled of whom 214 are eligible. 19 patients did not fulfill the inclusion criteria, and 29 patients were rejected based on low tumor content of the sample (<30% tumor cells). An interim analysis will be performed after 300 eligible stage 2 patients have been enrolled. Conclusion: The aim is to enroll 600 stage II patients to differentiate between 3 year RFS predicted by ColoPrint and clinical factors.