After describing the association of a rash on EGFR inhibitors with overall better outcomes on this class of agents, we can now take a step back and recognize that the rash can be an annoyance at the very least and sometimes a real problem.

An acne-like rash or dry skin is a very common side effect of the drugs that target the epidermal growth factor receptor, with approximately 3/4 of patients who receive the EGFR tyrosine kinase inhbitor tarceva/erlotinib experiencing skin toxicity. Similar skin toxicities are also seen, but a bit less commonly, with the very similar drug iressa/gefitinib, and also frequently with erbitux/cetuximab, a monoclonal antibody that is less well studied in lung cancer.

Since the earliest clinical trials of EGFR inhibitors in NSCLC, certain clinically defined patient subsets became identified as more likely to show a benefit than others. Such studies suggested that women, patients with adenocarcinomas rather than squamous cell carcinomas, Asian patients, and never-smokers compared with current or former smokers were the patients who would do well with EGFR tyrosine kinase inhibitors like gefitinib (Iressa) or erlotinib (Tarceva).

Thus far, the vast majority of patients who have an initial response to EGFR tyrosine kinase inhibitors like Iressa and Tarceva will eventually become resistant to them.