Pre-CCRT Systemic Inflammation Index (SII) and Neutrophil-To-Lymphocyte Ratio (NLR) are Better Than Platelet-To-Lymphocyte Ratio (PLR) as the Predictors for pCR in Rectal Cancer Patients Receiving Neoadjuvant Concurrent Chemoradiotherapy (CCRT)

Abstract

of vertebral T12, and 75.7% of the LNs were seen above the border of 2 cm inferior to the left renal artery, which often near the bottom of vertebral L2. Horizontally, 80% of LNs in celiac level were located within the region confined by the anterior surface of aorta, inferior vena cava (IVC), portal vein, splenic vein and celiac branches. In the superior mesenteric artery (SMA) level, all the LNs except 1 post-aortic LNs were behind the anterior edge of the SMA and anterior to the posterior edge of aorta, 85% were left to the left edge of IVC, and 95% were within 1.5 cm of the left side of the SMA. In the region beneath SMA, 92.7% of LNs appeared right to the lateral edge of the left psoas major (LPM), and all the LNs lied behind the anterior surface of the left renal vein or adjacent to the anterior surface of the aorta, left to the right border of the IVC, and anteriorly to the vertebral and the anterior edge of the LPM. The proposed CTV from the middle level of vertebral T12 to the 2cm below the left renal artery or the bottom of vertebral L2 (depending on which one is lower) with aforementioned boundaries can cover 74.52% of the LNs in the studied group. The postoperative RT treatment plan which included the commonly used T-shield field and the proposed CTV for RetroLNs in three simulated cases all met with satisfactory in the dosimetric analysis. Conclusion: The proposed CTV is the first that focus on the high-risk area of RetroLNs failure in LTESCC patients treated after surgery, and is also feasible in terms of dosimetric performance. The result can serve as a reference for future study to better improve the disease control in LTESCC.