Amplification of SKI is a prognostic marker in early colorectal cancer.

Background: Improved risk stratification of early colorectal cancer might help to better select patients for adjuvant treatment. Alterations in the transforming growth factor-beta (TGF-beta) pathway have frequently been found in colorectal cancer, but their impact on prognosis remains controversial. We therefore analyzed two transcriptional corepressors of the TGF-beta signaling pathway with respect to prognosis and prediction of chemotherapy benefit in early colorectal cancer.

Methods: The gene copy status of SKI and SNON was analyzed by use of quantitative real-time polymerase chain reaction in 179 colorectal tumor biopsies, which had been collected from a randomized multicenter trial of the Swiss Group for Clinical Cancer Research (SAKK).

Results: Partial or complete allelic loss was found in 41.5% and 55.2% for SKI and SNON, whereas amplification was found in 10.1% and 15.1%, respectively. Multivariate Cox analysis showed that gene amplification of SKI independently predicted reduced relapse-free [hazard ratio (HR) for relapse 2.08, P =.049] and overall survival (HR for death 2.62, P =.012). In contrast, deletion of SKI and the gene copy status of SNON were not significantly correlated with prognosis.

Conclusion: Amplification of SKI is a negative prognostic marker in early-stage colorectal cancer. This marker should help to improve risk stratification to better select patients for adjuvant therapy. Confirmatory investigations are warranted.