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Endothelial growth factor receptor inhibition after radiotherapy.

In 2005, a 62-year-old man was diagnosed with stage IIIB non-small cell lung cancer and treated with sequential chemoradiotherapy. Approximately 2 years later, he was treated with the endothelial growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) gefitinib. Eight days after starting getitinib therapy, he experienced grade 3 skin toxicity on the chest and shoulders but not in the previous radiotherapy field (Figure 1).1,2 Despite the severity of the skin toxicity, the patient did not obtain any benefit from this treatment. In reviewing the existing literature on this topic, we observed that the sequential approach of radiotherapy followed by EGFR-TKI does not seem to have a synergic or additive effect, as observed with the concomitant approach. Conversely, this effect seems to be detrimental, perhaps by inducing a decrease in expression and activity of EGFR. This effect seems to be milder if EGFR-TKI is administered immediately after radiotherapy (within 3 weeks) and much stronger when administered after a longer time from radiotherapy.3,4 These data suggest that the decrease of EGFR expression after radiotherapy may have a dramatic role in explaining the negative preliminary results of SWOG 0023, which is the only clinical study available so far.5 This observation raises the question of whether skin toxicity sparing can be considered a surrogate of lack of tumor response to EGFR-TKIs.