To summarize, this study allowed the identification of three inflammatory-associated genes (ARG1, BCL2L1, and MYC) whose expression is consistently modified in cancer patients by the radiotherapy treatment more than a month after the beginning of the treatment and, although these results require confirmation and extension, it suggests the possibility of predicting the severity of radiation toxicity by monitoring the leukocyte mRNA levels of specific genes (for example, CD40, OAS2, and CXCR1). This evidence concerns the gene CD40 and cancer.