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.