Objective:To compare the setup errors in the supraclavicular regions of two different postures (arms placed on each side of the body, namely the body side group; arms crossed and elbows placed above forehead, namely the uplifted group) using the chest and abdomen flat frame fixation device in lung and esophageal cancer.Methods:Clinical data of patients with stage Ⅰ to Ⅳ lung or esophageal cancer who received three-dimensional radiotherapy with chest and abdomen flat frame fixation device in our institution from November 2020 to April 2021 were retrospectively analyzed. The setup errors of two postures were compared.Results:A total of 56 patients were included, including 31 patients (55%) in the body side group and 25 patients (45%) in the uplifted group. A total of 424 CBCTs were performed in the whole group. The overall setup errors in the X, Y and Z directions were similar in both groups ( P>0.05). The setup errors of sternoclavicular joint in the X and RZ directions in the body side group were significantly smaller than those in the uplifted group [(0.163±0.120) cm vs. (0.209 ±0.152) cm, P=0.033; 0.715°±0.628° vs. 0.910°±0.753°, P=0.011]. The setup errors of acromioclavicular joint in the Y, Z and RZ directions in the body side group were significantly smaller than those in the uplifted group [(0.233±0.135) cm vs. (0.284±0.193) cm, P=0.033; (0.202±0.140) cm vs. (0.252±0.173) cm, P=0.005; 0.671°±0.639° vs. 0.885°±0.822°, P=0.023]. The margins of target volume for setup errors were smaller in the X (0.45 cm vs. 0.54 cm) and Y (0.54 cm vs. 0.65 cm) directions of the sternoclavicular joint, as well as in the Y (0.59 cm vs. 0.78 cm) and Z directions (0.53 cm vs. 0.72 cm) of the acromioclavicular joint in the body side group. Conclusions:For lung and esophageal cancer patients requiring supraclavicular irradiation, the body side group yields smaller setup errors and corresponding margins of target volume than the uplifted group. In clinical practice, it is necessary to take comprehensive consideration of the accuracy of radiotherapy and additional radiation of the limbs to select appropriate posture.

Objective: To investigate the anti-tumor effect of CTL cells on colon cancer xenograft in nude mice after knocking out the immune check point CTLA-4 by CRISPR/Cas9 technology. Methods: A specific small guide RNA (sgRNA) for CTLA-4 was designed to construct sgRNA/Cas9 plasmid, which was then transfected into CTL using a lentiviral vector to obtain CTL cells with CTLA-4 deletion (CTLA-4 KO CTL). The transfection efficiency of the plasmid and the deletion efficiency of CTLA-4 were verified. BALB/c nude mice were randomly divided into two groups to prophylactically inoculate CTLA-4 KO CTL (experimental group) or CTL (control group); 3 days later, the animals of two groups were inoculated with colon cancer cell line LS174-T to observe the tumor formation rate and tumor formation time. After constructing colon cancer xenograft model in nude mice, the animals were randomly divided into two groups, respectively treated with CTLA-4 KO CTL (experimental group) and CTL (control group) cells to observe the tumor growth volume and survival time of mice. The serum levels of TNF-α and IFN-γ in nude mice were detected. Results: sgRNAwas designed and CRSIPR/Cas9 system with lentivirus as vector was successfully constructed. CTL cells were transfected with the established CRSIPR/ Cas9 system, and the highest transfection efficiency was up to (28.80±0.62)%. After transfection, the deletion efficiency of CTLA-4 was detected by Flow cytometry. The CTLA-4 expression of CTLA-4 KO CTL group was significantly lower than that of CTL group [(0.91±0.25)% vs (42.70±2.72)%, P<0.05]. In prophylactic assay, the formation rate of colon cancer xenografts in the experimental group was significantly lower than that in the control group(33.33%vs100%,P<0.05). In treatment assay, the tumor volume in the experimental group was significantly inhibited compared with the control group ([503±23.9] vs [911.2±51.4] mm3, P<0.05), and the survivaltimeoftheexperimentalgroupwassignificantlyprolonged (mediansurvivaltime:78dvs42d,P<0.05); Moreover, the secretion levels of serumTNF-α([268.93±17.04]pg/mlvs[148.26±20.07]pg/ml,P<0.05) and IFN-γ(315.38±18.67 pg/ml vs 202.92±29.32 pg/ml, P<0.05) in the experimental group were significantly higher than those in the control group. Conclusions: The lentiviral vector CRSIPR/Cas9 system is an effective gene editing method; its successful deletion of CTLA-4 in CTL cells can significantly inhibit the tumor formation rate of colon cancer xenografts in nude mice and enhance the anti-tumor effect of CTLon colon cancer xenografts.