Changes in c-Kit expression levels during the course of radiation therapy for nasopharyngeal carcinoma

In the era of intensity-modulated radiotherapy, distant metastasis is currently the main cause of treatment failure for nasopharyngeal carcinoma (NPC). Additional therapeutic strategies are required to control the metastasis and improve survival. One strategy is targeted therapy, for example against c-Kit. In the current study, the frequency of c-Kit expression was determined immunohistochemically in 106 NPC patients. c-Kit expression changes during the course of radiation therapy were detected in 41 cases via weekly biopsy. Twelve cases (11.3%) had c-Kit expression scores of 3⁺ and 16 (15.1%) had scores of 2⁺. Thus, c-Kit overexpression (2⁺ or 3⁺) was observed in 28 (26.4%) patients. There were 35 (33.0%) and 43 (40.6%) patients with c-Kit expression scores of 1⁺ and 0, respectively. Furthermore, a trend of decreased c-Kit expression was observed after commencing radiotherapy according to the 41 NPC patients who were biopsied weekly. Therefore, c-Kit overexpression was identified to be common in NPC, and evaluating c-Kit as a therapeutic target for metastatic NPC via c-Kit overexpression subsequent to first line treatment may be of interest. To the best of our knowledge, the present study is the first to demonstrate a trend of decreased c-Kit expression during the course of radiotherapy.