IL17A and cancer: Furthermore, studies have shown elevated IL-17A expression levels and IL-17A-positive cell density in normal lung tissues after exposure to irradiation.14,49, , –52 Studies also reported that changes in IL-17A-positive cell populations can predict the therapeutic response of RT in cancers.43,44,53, –55 For example, Theobald et al.56 revealed that increased numbers of Th17 cells in blood were associated with resistance and recurrence in cervical cancer patients after chemoradiotherapy, suggesting their potential as predictors of therapeutic response.