[Long-term prognostic analysis on complete/near-complete clinical remission for mid-low rectal cancer after neoadjuvant chemoradiotherapy].

Objective: To investigate the long-term outcome of organ preservation with local excision or "watch and wait" strategy for mid-low rectal cancer patients evaluated as clinical complete remission (cCR) or near-cCR following neoadjuvant chemoradiotherapy (NCRT).
Methods: Clinical data of 62 mid-low rectal cancer patients evaluated as cCR/near-cCR after NCRT undergoing organ preservation surgery with local excision or receiving "watch and wait" strategy at Department of Gastrointestinal Surgery, Peking University Cancer Hospital and Institute from March 2011 to August 2017 were retrospectively analyzed. According to the approximate 1:2 pairing, 123 patients who underwent radical resection with complete pathological remission(ypCR) after neoadjuvant chemotherapy during the same period were selected for prognosis comparison. The primary endpoint of the study was 3-year non-regrowth disease-free survival (NR-DFS) and tumor specific survival (CSS). Survival analysis was performed using the Kaplan-Meier curve (Log-rank method). The secondary endpoint of the study was 3-year organ preservation and sphincter preservation.
Results: The retrospective study included 38 male and 24 female patients. The median age was 60 (31-79) years and the median distance from tumor to anal verge was 4(1-8) cm. The ratio of cCR and near-cCR was 79.0%(49/62) and 21.0%(13/62) respectively. Local regrowth rate was 24.2%(15/62). Of 15 with tumor regrowth, 9 patients received salvage radical rectal resection and no local recurrence was found during follow-up; 4 patients received salvage local excision among whom one patient had a local recurrence occurred patient; 2 patients refused further surgery. The overall metastasis rate was 8.1%(5/62), including resectable metastasis(4.8%,3/62) and unresectable metastasis (3.2%,2/62). The valid 3-year organ preservation rate and sphincter preservation rate were 85.5%(53/62) and 95.2%(59/62) respectively. The median follow-up was 36.2(8.6-89.0) months. The 3-year NR-DFS of patients with cCR and near-cCR was 88.6% and 83.1% respectively, which was not significantly different to that of patients with ypCR (94.7%, P=0.217). The 3-year CSS of patients with cCR and near-cCR was both 100%, which was not significantly different to that of patients with ypCR(93.4%, P=0.186).
Conclusions: Mid-low rectal cancer patients with cCR or near-cCR after NCRT undergoing organ preservation with local excision or receiving "watch and wait" strategy have good long-term prognosis with low rates of local tumor regrowth and distant metastasis, which is similar to those with ypCR after radical surgery. This treatment mode may be used as an option for organ preservation in mid-low rectal cancer patients with good tumor remission after NCRT.