The invention belongs to the field of 
molecular biology, and particularly relates to a 
sarcoma radiotherapy resistance-related 
diagnostic marker and application. According to application of IF18B as asarcoma biomarker, the IF18B is highly expressed in 
sarcoma tissue, and tumor 
cell radiotherapy sensitivity can be improved by inhibiting 
kinesin family member 18B (KIF18B) expression. According to asarcoma detection product, the 
sarcoma detection product includes a 
reagent for detecting KIF18B expression, and is a product used for sarcoma diagnosis, radiotherapy means 
therapeutic effect evaluation and prognosis judgment. According to the 
diagnostic marker, genes significantly differential in 
carcinoma and para-
carcinoma tissues in all sarcoma subtypes are widely screened, and are intersected with 
differentially expressed genes (DEGs) in 
carcinoma and para-carcinoma tissues of 
soft tissue sarcoma in a The 
Cancer Genome Atlas (TCGA) 
database, and it is the first time to discover that thegenes can be used as targets in all subtypes of sarcomas so as to improve huge differences of treatment schemes for patients with different subtypes of sarcomas at present; and the radiotherapy resistance-
related gene KIF18B is obtained by further screening, which proves that the radiotherapy sensitivity of sarcoma cells can be enhanced by inhibiting the KIF18B, and the KIF18B can be used as a specific target for sarcoma radiotherapy. According to the 
diagnostic marker, by taking the KIF18 as the biomarker and with a 
targeting therapy, a new thought is provided for sarcoma treatment, and detection indexes are also provided for radiotherapy means 
therapeutic effect evaluation and prognosis judgment, and the diagnostic marker has important clinical application value.