Molecular Profiling of EGFR Status to Identify Skin Toxicity in Colorectal Cancer: A Clinicopathological Review

Colorectal cancer (CRC) represents an important health problem, being the third most common type of cancer. In Romania, the CRC incidence has doubled over the years. Both environmental factors and genetic susceptibility are very important for the pathogenesis of CRC. The epidermal growth factor receptor (EGFR) plays an extremely important role in CRC tumorigenesis. Overexpression or dysregulation of EGFR pathway molecules are frequently associated with tumor aggressiveness and patient response to treatment. Based on these considerations, EGFR became one of the first targets of molecular therapies used in CRC. At present, cetuximab and panitumumab are considered to be essential in the treatment of patients with metastatic colorectal cancer expressing the KRAS wild-type gene and EGFR. The main adverse effect for both cetuximab and panitumumab is skin toxicity, present in approximately 80% of patients. The risk of secondary infections, in particular of bacterial infections, is also increased. Cases of staphylococcal infection associated with skin peeling, cellulite, erysipelas, and even Staphylococcus sepsis, were reported. For a long time cutaneous toxicity has been a positive predictor in the efficacy of anti-EGFR treatment, but compliance with treatment and the quality of life of patients with metastatic CRC decreases in the presence of these skin reactions. That is why we emphasize the necessity and importance of using a modern method (molecular analysis of gene polymorphisms possibly supplemented by targeted confocal laser endomicroscopy) to identify a molecular diagnosis, in order to foresee and prevent the appearance of skin reactions and to manage skin toxicity.