Neoadjuvant Rectal Score And Downstaging Depth Score As Prognosis Predictors For Patients With Locally Advanced Rectal Cancer

To evaluate the prognostic significance of neoadjuvant rectal (NAR) score and downstaging depth score (DDS) after neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC). Retrospective analysis was performed for 200 patients with LARC (T3-4 and/or N1-2, M0), who were initially treated in the department of radiation oncology from Mar. 2015 to Mar. 2018. All patients had baseline MRI assessments and received nCRT and radical resection. All patients received preoperative radiotherapy with doses of 45.0-50.0Gy and concurrent capecitabine. The median interval between surgery and nCRT was 9.2 weeks (5.5-20.7 weeks). The relationship of NAR score and DDS (DDS = pretreatment score-posttreatment score; The T0-4N0 stages were 0 to 4 points, respectively, and the T0.4N (+) stages were 5 to 9 points, respectively.) and prognosis was analyzed, and the area under the receiver-operating characteristic (ROC) curves was calculated. The accuracy of NAR score and DDS in predicting the 3-year disease-free survival (DFS) was evaluated. The 3-year DFS calculated using the Kaplan-Meier method, and compared by the Log rank test. The median distance from tumor edge to anal verge was 4 cm. 188 (94%) patients finished radiation of 45-50Gy in 25 fractions, as well as concurrent chemotherapy. After chemoradiotherapy, T-downstage rate and N-downstage rate of the whole group were 40.7% and 62.7%, respectively. The R0 resection rate was 82.0%. With median follow-up of 31 months (14-39 months),14 patients (7.0%) died and 45 patients (22.5%) experienced relapse (4 local and distant, 41 distant only). The 3-year DFS rate was 75.9% (95% CI: 69.2,82.5). The univariate survival analysis showed that DDS and NAR score were correlated with 3-year DFS (P<0.05). The median DDS and NAR score were 5 and 14.98. In terms of DDS, the 3-year DFS rate were 56.4%, 81.3% and 86.2% in ≤0 group, 0-5 group and >5 group, respectively (p = 0.018). In terms of NAR, the 3-year DFS rate were 90.1%, 73.8% and 53.6% in ≤8 group, 8-16 group and >16 group, respectively(p = 0.000).The cutoff value of DDS on 3-year DFS was 0; The sensitivity and specificity of predicting the DFS were 48.9% and 73.6%, respectively with the area under curve (AUC) 0.63. The cutoff value of NAR score on 3-year DFS was 8.43; The sensitivity and specificity of predicting the DFS were 88.2% and 49.0%, respectively with the area under curve (AUC) 0.68. Youden index of DDS and NAR score were 0.22 and 0.31 respectively (p = 0.0302). High DDS and low NAR scores after nCRT indicate good prognosis for patients with LARC, but which scores is more valuable needs further investigation.