Research progress in the colistin resistance gene mcr-1 / 中国人兽共患病学报

Polymyxin antibiotics,particularly polymyxin B and polymyxin E(colistin),are often considered a last line of defense against penicillin carbapenem-resistant Enterobacteriaceae(CRE),because of their favorable clinical antibacterial effects.However,the emergence and spread of plasmid-mediated colistin resistance genes(mcr),and their multiple isoforms,have posed a substantial threat to public health in recent years.The mcr-1 genes exhibit complexity in both host and transmis-sion routes,and diversity in both the genetic environment and ecological locus distribution.Herein,we discuss the prevalence,transmission routes,drug resistance and transmission mechanisms of mcr-1 positive isolates,on the basis of epidemiological studies of Enterobacteriaceae carrying mcr-1 worldwide.to provide a theoretical reference for researchers.

The efficacy of radiotherapy based combined therapy for unresectable locally invasive bladder cancer and its associated factors analysis / 中华肿瘤杂志

Objective: Retrospective analysis of the efficacy and influencing factors of bladder preservation integrated therapy for unresectable invasive bladder cancer confined to the pelvis was done, also including the bladder function preservation and adverse effects analysis. Methods: Sixty-nine patients with unresectable locally invasive bladder cancer who received radiotherapy-based combination therapy from March 1999 to December 2021 at our hospital were selected. Among them, 42 patients received concurrent chemoradiotherapy, 32 underwent neoadjuvant chemotherapyand 43 with transurethral resection of bladder tumors (TURBT) prior to radiotherapy. The late adverse effect of radiotherapy, preservation of bladder function, replase and metastasis and survival were followed-up. Cox proportional hazards models were applied for the multifactorial analysis. Results: The median age was 69 years. There were 63 cases (91.3%) of uroepithelial carcinoma, 64 of stage Ⅲ and 4 of stage Ⅳ. The median duration of follow-up was 76 months. There were 7 grade 2 late genito urinary toxicities, 2 grade 2 gastrointestinal toxicities, no grade 3 or higher adverse events occurred. All patients maintained normal bladder function, except for 8 cases who lost bladder function due to uncontrolled tumor in the bladder. Seventeen cases recurred locally. There were 11 cases in the concurrent chemoradiotherapy group with a local recurrence rate of 26.2% (11/42) and 6 cases in the non-concurrent chemoradiotherapy group with a local recurrence rate of 22.2% (6/27), and the difference in local recurrence rate between the two groups was not statistically significant (P=0.709). There were 23 cases of distant metastasis (including 2 cases of local recurrence with distant metastasis), including 10 cases in the concurrent chemoradiotherapy group with a distant metastasis rate of 23.8% (10/42) and 13 cases in the non-concurrent chemoradiotherapy group with a distant metastasis rate of 48.1% (13/27), and the distant metastasis rate in the non-concurrent chemoradiotherapy group was higher than that in the concurrent chemoradiotherapy group (P=0.036). The median 5-year overall survival (OS) time was 59 months and the OS rate was 47.8%. The 5-year progression-free survival (PFS) time was 20 months and the PFS rate was 34.4%. The 5-year OS rates of concurrent and non-concurrent chemoradiotherapy group were 62.9% and 27.6% (P<0.001), and 5-year PFS rates were 45.4% and 20.0%, respectively (P=0.022). The 5-year OS rates of with or without neoadjuvant chemotherapy were 78.4% and 30.1% (P=0.002), and the 5-year PFS rates were 49.1% and 25.1% (P=0.087), respectively. The 5-year OS rates with or without TURBT before radiotherapy were 45.5% and 51.9% (P=0.233) and the 5-year PFS rates were 30.8% and 39.9% (P=0.198), respectively. Multivariate Cox regression analysis results showed that the clinical stage (HR=0.422, 95% CI: 0.205-0.869) was independent prognostic factor for PFS of invasive bladder cancer. The multivariate analysis showed that clinical stages (HR=0.278, 95% CI: 0.114-0.678), concurrent chemoradiotherapy (HR=0.391, 95% CI: 0.165-0.930), neoadjuvant chemotherapy (HR=0.188, 95% CI: 0.058-0.611), and recurrences (HR=10.855, 95% CI: 3.655-32.638) were independent prognostic factors for OS of invasive bladder cancer. Conclusion: Unresectable localized invasive bladder cancer can achieve satisfactory long-term outcomes with bladder-preserving combination therapy based on radiotherapy, most patients can retain normal bladder function with acceptable late adverse effects and improved survival particularly evident in patients with early, concurrent chemoradiotherapy and neoadjuvant chemotherapy.

Stereotactic body radiation therapy for patients with lung and liver oligometastases from colorectal cancer: a phase Ⅱ trial / 中华肿瘤杂志

Objective: To explore the safety and effectiveness of stereotactic body radiation therapy (SBRT) for oligometastases from colorectal cancer (CRC). Methods: This is a prospective, single-arm phase Ⅱ trial. Patients who had histologically proven CRC, 1 to 5 detectable liver or lung metastatic lesions with maximum diameter of any metastases ≤5 cm were eligible. SBRT was delivered to all lesions. The primary endpoint was 3-year local control (LC). The secondary endpoints were treatment-related acute toxicities of grade 3 and above, 1-year and 3-year overall survival (OS) and progression free survival (PFS). Survival analysis was performed using the Kaplan-Meier method and Log rank test. Results: Petients from 2016 to 2019 who were treated in Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. Forty-eight patients with 60 lesions were enrolled, including 37 liver lesions and 23 lung lesions. Forty-six patients had 1 or 2 lesions, with median diameter of 1.3 cm, the median biologically effective dose (BED(10)) was 100.0 Gy. The median follow-up was 19.5 months for all lesions. Twenty-five lesions developed local failure, the median local progression free survival was 15 months. The 1-year LC, OS and PFS was 70.2% (95% CI, 63.7%~76.7%), 89.0% (95% CI, 84.3%~93.7%) and 40.4% (95%CI, 33.0%~47.8%). The univariate analysis revealed that planning target volume (PTV) and total dose were independent prognostic factors of LC (P<0.05). For liver and lung lesions, the 1-year LC, OS and PFS was 58.7% and 89.4% (P=0.015), 89.3% and 86.5% (P=0.732), 30.5% and 65.6% (P=0.024), respectively. No patients developed acute toxicity of grade 3 and above. Conclusion: SBRT is safe and effective treatment method for oligometastases from CRC under precise respiratory motion management and robust quality assurance.

Oral contrast agents lead to underestimation of dose calculation in volumetric-modulated arc therapy planning for pelvic irradiation / 中华医学杂志(英文版)

BACKGROUND@#The effects of oral contrast agents (OCAs) on dosimetry have not been studied in detail. Therefore, this study aimed to examine the influence of OCAs on dose calculation in volumetric-modulated arc therapy plans for rectal cancer.@*METHODS@#From 2008 to 2016, computed tomography (CT) images were obtained from 33 rectal cancer patients administered OCA with or without intravenous contrast agent (ICA) and 14 patients who received no contrast agent. CT numbers of organs at risk were recorded and converted to electronic densities. Volumetric-modulated arc therapy plans were designed before and after the original densities were replaced with non-enhanced densities. Doses to the planned target volume (PTV) and organs at risk were compared between the plans.@*RESULTS@#OCA significantly increased the mean and maximum densities of the bowels, while the effects of ICA on these parameters depended on the blood supply of the organs. With OCA, the actual doses for PTV were significantly higher than planned and doses to the bowel increased significantly although moderately. However, the increase in the volume receiving a high-range doses was substantial (the absolute change of intestine volume receiving ≥52 Gy: 1.46 [0.05-3.99, cubic centimeter range: -6.74 to 128.12], the absolute change of colon volume receiving ≥50 Gy: 0.34 [0.01-1.53 cc, range: -0.08 to 3.80 cc]. Dose changes due to ICA were insignificant. Pearson correlation showed that dose changes were significantly correlated with a high intestinal volume within or near the PTV (ρ > 0.5, P  0.3, P < 0.05).@*CONCLUSIONS@#Contrast agents applied in simulation cause underestimation of doses in actual treatment. The overdose due to ICA was slight, while that due to OCA was moderate. The bowel volume receiving ≥50Gy was dramatically increased when OCA within the bowel was absent. Physicians should be aware of these issues if the original plan is barely within clinical tolerance or if a considerable volume of enhanced intestine is within or near the PTV.

Neoadjuvant rectal score in prognostic prediction of clinical stage Ⅲ middle-low rectal cancer / 中华放射肿瘤学杂志

Objective To investigate the effects of downstaging and neoadjuvant reetal(NAR) score on the prognosis of patients with clinical stage Ⅲ middle-low rectal cancer undergoing preoperative concurrent chemoradiotherapy.Methods From 2006 to 2014,195 patients who were admitted to our hospital and diagnosed with clinical stage Ⅲ middle-low rectal cancer by pelvic magnetic resonance imaging or computed tomography were enrolled.All patients received preoperative radiotherapy with doses of 42-50.4 Gy (median:50 Gy,93.8％ of patients received doses of ≥ 50 Gy) and concurrent chemotherapy with capecitabine ± oxaliplatin.Total mesorectal (R0) excision surgery was performed at 4-15 weeks (median:7 weeks) after concurrent chemoradiotherapy.The effects of downstaging (stage yp0-Ⅱ) and NAR score (calculated based on cT staging and ypT/N staging) on the prognosis were evaluated.The 3-year disease-free survival (DFS) rate was calculated using the Kaplan-Meier method and analyzed by log-rank test.Results In all the patients,the median follow-up time was 44 months (6.7-125.5 months);the 3-year DFS rate was 76.8％.Downstaging after preoperative chemoradiotherapy was a significant prognostic factor for the 3-year DFS (92.2％ vs.56.8％,P=0.000).The median NAR score was 15.0(0-65.0) in all the patients.Patients with NAR scores of ≤ 15.0 had significantly improved 3-year DFS than those with NAR scores of＞15.0(90.1％ vs.57.0％,P=0.001).In patients with downstaging,those with NAR scores of ≤8.4 had significantly improved prognosis compared with those with NAR scores of＞ 8.4(95.1％ vs.87.5％,P=0.022).Conclusions Patients with downstaging after preoperative concurrent chemoradiotherapy for stage c Ⅲ middle-low rectal cancer have satisfactory prognosis.The NAR score is an effective prognostic predictor.