EGFR and HER3 mRNA expression levels predict distant metastases in locally advanced rectal cancer.

Aberrant activation of the HER signaling pathways plays a critical role in the invasive and metastatic potential of tumors. The aim of this study was to address whether, in rectal cancer, alterations of these pathways could have a value as prognostic factors to be used to identify patients who are at risk of distant metastases. Therefore, the mRNA expression of the four members of the HER family as well as the frequency of PTEN allelic loss and KRAS/BRAF mutations were determined in pretreatment biopsies from a series of 100 locally advanced rectal cancers and then their ability to predict distant metastases was evaluated. Over-expression of EGFR (p = 0.021), HER2 (p = 0.011) and HER3 (p = 0.020) was significantly associated with worse metastasis-free survival in univariate analysis. In multivariate analysis, both over-expression of EGFR (p = 0.028) and HER3 (p = 0.011) remained independent prognostic factors for distant metastasis. In conclusion, quantification of EGFR and HER3 mRNA expression in pretreatment biopsies may be useful to identify patients who are at risk of developing metastases.