Prognostic Significance of Neoadjuvant Rectal Scores in Preoperative Short-Course Radiotherapy and Long-Course Concurrent Chemoradiotherapy for Patients with Locally Advanced Rectal Cancer

Background This study aimed to investigate the prognostic factors and the utility of the neoadjuvant rectal (NAR) score for patients who have locally advanced rectal cancer (LARC) treated with preoperative short-course radiotherapy (SRT) or long-course concurrent chemoradiotherapy (CRT). Methods Of 314 consecutive stage 2 or 3 rectal cancer patients enrolled from January 2006 to December 2017, 205 underwent preoperative SRT (2500 cGy/5 fractions), and 109 underwent preoperative CRT (4200-5080 cGy/21-28 fractions) after total mesorectal excision (TME). The study calculated NAR scores using the following equation: [5 pN - 3(cT - pT) + 12](2)/9.61. Results The multivariate analysis showed that age above 65 years, pT4, pN2, NAR scores higher than 16, and distance from anal verges (< 8 cm) were significant prognostic factors for overall survival (OS), whereas, pN2, NAR scores lower than 16, and distance from anal verges (< 8 cm) were significant prognostic factors for disease-free survival (DFS) and distant metastasis (DM). The patients with an NAR score higher than 16, had a 5-year OS rate of 67.6%, a DFS rate of 56.9%, a locoregional recurrence (LRR) rate of 7.7%, and a DM rate of 35% compared with corresponding rates of 87.6%, 76.7%, 5.4%, and 7.2% for the patients with an NAR score of 16 or lower (p < 0.001 for OS, < 0.001 for DFS, 0.25 for LRR, and < 0.001 for DM). Conclusions For patients who undergo SRT or CRT for LARC, a higher NAR score is associated with worse OS and DFS and higher DM rates at 5 years. The NAR score could be used as a short-term surrogate end point after neoadjuvant therapy for LARC.