OBJECTIVETo investigate the safety and efficacy of organ preservation surgery or "watch and wait" strategy for rectal cancer patients who are evaluated as clinical complete response(cCR) or near-cCR following neoadjuvant chemoradiotherapy (nCRT).

METHODFrom March 2011 to June 2016, 35 patients with mid-low rectal cancers who were diagnosed as cCR or near-cCR following nCRT underwent organ preservation surgery with local excision or surveillance following "watch and wait" strategy in the Peking University Cancer Hospital. All the patients received re-evaluation and re-staging 6-12 weeks after the completion of nCRT, according to Habr-Gama and MSKCC criteria for the diagnosis of cCR or near-cCR. The near-cCR patients who received local excision and were pathologically diagnosed as T0Nx were also regarded as cCR. The end-points of this study included organ-preservation rate (OPR), sphincter-preservation rate (SPR), non-re-growth disease-free survival (NR-DFS), stoma-free survival, cancer-specific survival (CSS) and overall survival(OS). Kaplan-Meier curve was used to estimate the survival data at 3 years.

RESULTSA total of 35 cases were analyzed including 24 males (68.6%) and 11 females (31.4%). The median age was 60 (range 37-79) years and the median distance from tumor to anal edge was 4(2-8) cm. Thirty-three patients received 50.6 Gy/22f IMRT with capecitabine and two patients received 50 Gy/25f RT with capecitabine. The cCR and near-cCR rates were 74.3%(26/35) and 25.7%(9/35) respectively. Excision biopsy was performed in 4 near-cCR cases to confirm the diagnosis of cCR. The non-re-growth DFS rate was 14.3%(5/35) and the median time of tumor re-growth was 6.7 (4.7-37.4) months. In five patients with tumor re-growth, four were salvaged by radical rectal resections and one received local excision. The distant metastasis rate was 5.7%(2/35), one patient presented resectable liver metastasis and received radical resection, another patient presented multiple bone metastases and was still alive. The median follow-up time was 43.7(6.1-71.4) months. At three years, the organ-preservation rate was 88.6%(31/35), the sphincter-preservation rate was 97.1% (34/35). No local recurrence was observed in five patients who received salvage surgery. The non-re-growth DFS was 94.0%. Three patients died of non-rectal cancer related events. The cancer-specific survival was 100%, the overall survival was 92.7% and the stoma-free survival rate was 90.0%.

CONCLUSIONSOrgan preservation surgery or "watch and wait" strategy for cCR or near-cCR patients is feasible and achieves good outcomes. This strategy can be an alternative to standard care, improve patient's quality of life and facilitate tailored treatment for mid-low rectal cancer following nCRT, however, it should be cautiously applied in near-cCR patients before local excision biopsy.