Objective To explore the change in anatomical volume during intensity?modulated radiotherapy (IMRT) for different stages of nasopharyngeal carcinoma (NPC) and its influence on dose distribution, and to assess the necessity to modify the IMRT plan. Methods Twenty?four patients with newly diagnosed NPC who received IMRT and chemotherapy were enrolled in the study, and were divided into early?intermediate group ( 12 cases ) and locally advanced group ( 12 cases ) according to the 2008 staging system for NPC. Each patient had a repeated CT scan at week 5 of radiotherapy, and target volume and organs at risk ( OAR) were contoured. The dose distribution of the original plan shown on CT was calculated. Changes in target volume, OAR anatomical volume, and dose distribution were analyzed, and paired t?test and Spearman correlation analysis were performed. Results In the early?intermediate group, gross target volume of neck positive lymph nodes (GTVnd) was reduced during radiotherapy (P=0. 059), and gross target volume of nasopharynx ( GTVnx ) , high?risk clinical target volume ( CTV1 ) , and parotid volume were reduced significantly during radiotherapy ( P= 0. 001, 0. 012, 0. 002, and 0. 000, respectively) . In locally advanced group, GTVnx , GTVnd , CTV1 , and parotid volume were significantly reduced during IMRT (P=0. 000, 0. 000, 0. 003, 0. 003, and 0. 000, respectively). Compared with the values before radiotherapy, the parotid dose increased significantly in the two groups during IMRT ( P=0. 044, 0. 026, 0. 033, and 0. 026, respectively;P=0. 024, 0. 016, 0. 030, and 0. 015, respectively) , and the increase in GTVnd dose was observed in the locally advanced group ( P= 0. 029 and 0. 049 ) . Conclusions It is recommended to perform another CT scan for patients with locally advanced NPC at week 5 of radiotherapy and formulate a new IMRT plan to maintain target volume dose and guarantee a safe parotid dose.

Objective To explore the relationship between the expression of lncRNA MGP-AS2 in bladder cancer tissues and the survival of bladder cancer patients,and to study the impact of MGP-AS2 on the biological function of bladder cancer cells and possible mechanism.Methods The TANRIC database was used to analyze MGP-AS2 expression level in bladder cancer tissues and its relation-ship with patient survival.Real-time quantitative polymerase chain reaction(RT-qPCR)was used to detect the expression level of MGP-AS2 in bladder cancer cell lines.The MGP-AS2 overexpression plasmid and negative control(NC)plasmid were transfected into bladder cancer 5637 cells,respectively,as the MGP-AS2group and NC group.Plate cloning experiment,cell scratch experiment and Tr-answell experiment were used to analyze the effects of MGP-AS2 overexpression on the proliferation,migration and invasion of bladder cancer 5637 cells.Dual-luciferase reporter gene experiment was used to verify the targeted binding between MGP-AS2 and miR-18a.The TANRIC database was used to analyze the correlation between MGP-AS2 and miR-18a expression.RT-qPCR method was used to analyze the effect of MGP-AS2 overexpression on the expression of miR-18a in bladder cancer 5637 cells.Western blot method was used to detect the effect of MGP-AS2 overexpression on the expression of Wnt/β-catenin signaling pathway proteins in bladder cancer 5637 cells.Results The expression level of MGP-AS2 in bladder cancer tissue was significantly lower than that in normal bladder tis-sues(P＜0.01).The overall survival and disease-free survival of patients with high expression of MGP-AS2 were significantly longer than those of patients with low expression of MGP-AS2(P＜0.01).The expression level of MGP-AS2 in bladder cancer cell lines were lower than those in SV-HUC-1 cells(P＜0.05).The bladder cancer cells with the lowest MGP-AS2 expression was 5637 cells(P＜0.01).Compared with the NC group,overexpression of MGP-AS2 could significantly inhibit the proliferation,migration and invasion a-bility of 5637 cells(P＜0.01).Dual-luciferase reporter gene experiment confirmed that MGP-AS2 could target and bind to miR-18a(P＜0.01).Compared with the NC group,overexpression of MGP-AS2 could downregulate the expression of miR-18a(P＜0.01).After overexpression of MGP-AS2,Wnt/β-catenin signaling pathway proteins were all down-regulated in bladder cancer 5637 cells(P＜0.01).Conclusion MGP-AS2 is low-expressed in bladder cancer,and the expression level of MGP-AS2 is correlated with the prognosis of bladder cancer patients.MGP-AS2 may inhibit the transduction of the Wnt/β-catenin signaling pathway by adsorbing miR-18a,thereby inhibiting the progression of bladder cancer.