PMC:6736480 / 10881-13060 JSONTXT

{"project":"2_test","denotations":[{"id":"31464897-14519861-68392314","span":{"begin":1593,"end":1595},"obj":"14519861"}],"text":"2.6 Data and statistical analysis\nWe calculated a sample size of 110 patients in this study, based on a rate of ypT0 of 20% observed in previous studies. The power was set at 80% and the 2-sided significance level set at 0.05, and the sample size was inflated by 10% to account for an ineligibility rate of 10%. Pathologic tumor response to CRT was divided into good and poor response groups using 3 different criteria as follows: ypT0 vs ypT1-4; ypT0-1 vs ypT2-4; or ypT0-2 vs ypT3-4. In the analysis of diagnostic performance of endoscopic and MR tumor response for predicting the good response group, post-CRT findings were scored on a 3-point scale: 3 for cCR, 2 for nearly-cCR, and 1 for non-cCR. For both endoscopic and MR tumor response, positive test results were defined as a score of 2 or higher and negative results were defined as a score of 1. For the combination of endoscopic and MR tumor response (combination modality), positive test results were defined as the sum of these 2 methods scores equaling 3 or higher and negative results were defined as the sum of the scores equaling 2. The sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs), and accuracy of endoscopic tumor response, MR tumor response, and the combination modality were calculated for differentiating the good response from the poor response groups, when applying each definition for the good response group (ypT0, ypT0-1, or ypT0-2). The area under the curves (AUCs) were also calculated from construction of the receiver operating characteristic (ROC) curve.[21] Pairwise comparison of AUCs of endoscopic tumor response, MR tumor response, and the combination modality were performed (endoscopy vs mrTRG, endoscopy vs combination modality, mrTRG vs combination modality). Generalized estimating equation (GEE) model was used to obtain statistically unbiased estimates. SPSS software version 20.0 for Windows (SPSS Corp, Chicago, IL) was used for analyses. Quantitative data were expressed as mean ± standard deviation and qualitative data as frequency and percent. All P-values were 2-sided, and P \u003c .05 was considered statistically significant."}