Oncologic Outcomes of ypT1-3N0 mid-Low Rectal Cancer Compared with pT1-3N0 Disease After Radical Resection

Abstract Background: Neoadjuvant chemoradiotherapy (CRT) can downstage rectal carcinoma, resulting in superior resectability, better local control and survival benefits. However, it is unclear whether patients treated with CRT and those who did not have similar outcomes at the same pathological stage. This study aimed to investigate the long-term outcomes of ypT1-3N0 mid-low rectal cancer who received neoadjuvant CRT followed by total mesorectal excision (TME) compared with pT1-3N0 rectal cancer immediately managed with surgery. Methods: We retrospectively enrolled 180 patients with pT1-3N0 or ypT1-3N0 rectal cancer located within 10cm from the anal edge who underwent TME between 2009 and 2015. Of these patients, 63 received neoadjuvant CRT, while 117 underwent radical proctectomy without preoperative therapy. The disease-free survival (DFS) and cancer-specific survival (CSS) were compared between the two groups. Results: Within a median follow-up time of 65 months, the 5-year DFS was lower in the CRT group than the non-CRT group (74.9% vs. 92.6%, P=0.001), and the 5-year CSS presented a similar trend as well (89.6 % vs. 97.1%, P=0.054). By subgroup analysis, the difference in DFS and CSS was mainly caused by the difference between ypT3N0 and pT3N0 disease (71.1% vs. 96.1%, P＜0.001 and 90.9% vs. 100%, P=0.029, respectively). However, patients with ypT1-2N0 had an analogous prognosis to those with pT1-2N0 disease (77.9% vs. 89.0%, P=0.225 and 88.1% vs. 94.2%, P=0.292, respectively). Multivariate analysis indicated that neoadjuvant CRT was not an independent predictor of DFS. Conclusion: After neoadjuvant CRT followed by TME, patients with ypT1-2N0 rectal cancer had an analogous prognosis to those with initial pT1-2N0 disease, whereas patients with ypT3N0 rectal cancer had worse prognosis compared with that of pT3N0 disease.