Improving the accuracy and consistency of clinical target volume delineation for rectal cancer by an education program

BACKGROUND Accurate target volume delineation is the premise for the implementation of precise radiotherapy.Inadequate target volume delineation may diminish tumor control or increase toxicity.Although several clinical target volume(CTV)delineation guidelines for rectal cancer have been published in recent years,significant interobserver variation(IOV)in CTV delineation still exists among radiation oncologists.However,proper education may serve as a bridge that connects complex guidelines with clinical practice.AIM To examine whether an education program could improve the accuracy and consistency of preoperative radiotherapy CTV delineation for rectal cancer.METHODS The study consisted of a baseline target volume delineation,a 150-min education intervention,and a follow-up evaluation.A 42-year-old man diagnosed with stage IIIC(T3N2bM0)rectal adenocarcinoma was selected for target volume delineation.CTVs obtained before and after the program were compared.Dice similarity coefficient(DSC),inclusiveness index(IncI),conformal index(CI),and relative volume difference[ΔV(%)]were analyzed to quantitatively evaluate the disparities between the participants’delineation and the standard CTV.Maximum volume ratio(MVR)and coefficient of variation(CV)were calculated to assess the IOV.Qualitative analysis included four common controversies in CTV delineation concerning the upper boundary of the target volume,external iliac area,groin area,and ischiorectal fossa.RESULTS Of the 18 radiation oncologists from 10 provinces in China,13 completed two sets of CTVs.In quantitative analysis,the average CTV volume decreased from 809.82 cm3 to 705.21 cm3(P=0.001)after the education program.Regarding the indices for geometric comparison,the mean DSC,IncI,and CI increased significantly,whileΔV(%)decreased remarkably,indicating improved agreement between participants’delineation and the standard CTV.Moreover,an 11.80%reduction in MVR and 18.19%reduction in CV were noted,demonstrating a smaller IOV in delineation after the education program.Regarding qualitative analysis,the greatest variations in baseline were observed at the external iliac area and ischiorectal fossa;61.54%(8/13)and 53.85%(7/13)of the participants unnecessarily delineated the external iliac area and the ischiorectal fossa,respectively.However,the education program reduced these variations.CONCLUSION Wide variations in CTV delineation for rectal cancer are present among radiation oncologists in China's Mainland.A well-structured education program could improve delineation accuracy and reduce IOVs.

Prognostic nomograms for predicting overall survival and causespecific survival of signet ring cell carcinoma in colorectal cancer patients

BACKGROUND Signet ring cell carcinoma(SRCC)is an uncommon subtype in colorectal cancer(CRC),with a short survival time.Therefore,it is imperative to establish a useful prognostic model.As a simple visual predictive tool,nomograms combining a quantification of all proven prognostic factors have been widely used for predicting the outcomes of patients with different cancers in recent years.Until now,there has been no nomogram to predict the outcome of CRC patients with SRCC.AIM To build effective nomograms for predicting overall survival(OS)and causespecific survival(CSS)of CRC patients with SRCC.METHODS Data were extracted from the Surveillance,Epidemiology,and End Results database between 2004 and 2015.Multivariate Cox regression analyses were used to identify independent variables for both OS and CSS to construct the nomograms.Performance of the nomograms was assessed by concordance index,calibration curves,and receiver operating characteristic(ROC)curves.ROC curves were also utilized to compare benefits between the nomograms and the tumor-node-metastasis(TNM)staging system.Patients were classified as high-risk,moderate-risk,and low-risk groups using the novel nomograms.Kaplan-Meier curves were plotted to compare survival differences.RESULTS In total,1230 patients were included.The concordance index of the nomograms for OS and CSS were 0.737(95%confidence interval:0.728-0.747)and 0.758(95%confidence interval:0.738-0.778),respectively.The calibration curves and ROC curves demonstrated good predictive accuracy.The 1-,3-,and 5-year area under the curve values of the nomogram for predicting OS were 0.796,0.825 and 0.819,in comparison to 0.743,0.798,and 0.803 for the TNM staging system.In addition,the 1-,3-,and 5-year area under the curve values of the nomogram for predicting CSS were 0.805,0.847 and 0.863,in comparison to 0.740,0.794,and 0.800 for the TNM staging system.Based on the novel nomograms,stratified analysis showed that the 5-year probability of survival in the high-risk,moderate-risk,and low-risk groups was 6.8%,37.7%,and 67.0%for OS(P<0.001),as well as 9.6%,38.5%,and 67.6%for CSS(P<0.001),respectively.CONCLUSION Convenient and visual nomograms were built and validated to accurately predict the OS and CSS rates for CRC patients with SRCC,which are superior to the conventional TNM staging system.

Consolidation chemotherapy with capecitabine after neoadjuvant chemoradiotherapy in high-risk patients with locally advanced rectal cancer:Propensity score study

BACKGROUND The effects of consolidation chemotherapy(CC) in neoadjuvant therapy in locally advanced rectal cancer(LARC) have been explored. However, the optimal neoadjuvant chemoradiotherapy(NCRT) and surgery interval, regimen, and cycles of chemotherapy remains unclear.AIM To evaluate the effects of one to two cycles of CC with capecitabine on high-risk patients with LARC without extending NCRT and surgery interval.METHODS We retrospectively evaluated high-risk patients with LARC, who were defined as having at least one of the following factors by magnetic resonance imaging: depth of invasion beyond the muscularis propria of more than 5 mm(c T3c-c T3d), T4, meso-rectal fascia or extramural vascular invasion positive, and treatment date between January 2015 and July 2019 in our center. Patients were divided into the CC and non-CC group according to whether they received CC(capecitabine 1000 mg/m^(2) twice daily from days 1 to 14 every 21 d) after NCRT. Propensity score matching(PSM) and inverse probability of treatment weight(IPTW) were used to balance the differences between the two groups. The main outcome was the complete response(CR) rate.RESULTS A total of 265 patients were enrolled: 136 patients in the CC group and 129 patients in the non-CC group. The median interval was 70 d(range, 37-168). The CR rate was 24.3% and 16.3%(P = 0.107) in the CC and non-CC groups’ original samples, respectively. After PSM and IPTW, the CR rate in the CC group was higher than that in non-CC group(27.6% vs 16.2%, P = 0.045;25.9% vs 16.3%, P = 0.045). The median follow-up was 39.8 mo(range, 2.9-74.8), and there were no differences in 3-year non-regrowth disease-free survival nor overall survival in the original samples(73.2% vs 71.9%, P = 0.913;92.3% vs 86.7%, P = 0.294), PSM(73.2% vs 73.5%, P = 0.865;92.5% vs 89.3%, P = 0.612), and IPTW(73.8% vs 72.1%, P = 0.913;92.4% vs 87.4%, P = 0.294). There was also no difference in grade 2 or higher acute toxicity during neoadjuvant therapy in the two groups(49.3% vs 53.5%, P = 0.492).CONCLUSION One to two cycles of CC with capecitabine after NCRT was safe and increased the CR rate in highrisk LARC but failed to improve the long-term outcomes.