Whether to perform radical TME or salvage chemoradiotherapy after local resection of intermediate-risk T1 rectal cancer is still controversial. A study based on the National Cancer Data Center showed that, because of the need for organ preservation, rescue chemoradiotherapy after local resection of rectal cancer was used in 10% of patients with T1N0 tumors and in 40% of patients with T2N0 tumors. However, the local recurrence caused by non-TME surgery is still the focus of concern for clinicians and patients. Previous retrospective studies have shown that there is no significant difference in overall survival and disease free survival between salvage CRT group and salvage TME group for patients with early rectal cancer after local resection. Pathological pT2 after local resection is the only independent risk factor for disease-free survival. However, limited to a single center and small sample size, the recurrence caused by salvage radiotherapy and chemotherapy should still be alert. Given these concerns, there is an urgent need to identify a better treatment regimen that can ensure reliable oncologic outcomes after local resection. Therefore, with TME as the control group and salvage chemoradiotherapy as the experimental group, we conducted a prospective, randomized, multicenter, non-inferiority clinical trial of the treatment effect of patients with intermediate-risk T1 and clinical stage N0M0 rectal cancer after local resection, to provide high-level evidence-based medical evidence for the final choice of these two salvage treatment methods.

In China, with the implementation of population-based early screening for colorectal cancer, more and more colorectal cancer are detected and diagnosed at an early stage. However, although operation method is improved, but it is reported that the radical rectal cancer surgery resection or by a combination of abdominal perineal resection (low) still has as much as 36% of surgical morbidity and functional prognosis and quality of life of the patients with a significant negative impact on. More than half of rectal cancer patients experienced different degrees of defecation disorder after surgery. Urinary incontinence, urinary retention and sexual dysfunction were also common. In addition, after total mesorectal excision (TME), patients often face many stoma-related complications such as stoma prolapse, bleeding, necrosis, and inability to reverse stoma. Dutch TME clinical studies reported ,19%of the patients with rectal cancer resection before low did not successfully complete protective colostomy HaiNa, long-term or permanent colostomy rate is as high as 40%. After abdominoperineal resection, up to 40% of patients develop perineal wound complications. Under the guidance of the previous concept of tumor control, the disadvantages caused by radical surgery seem to be acceptable. However, with the deepening of research, more and more scholars believe that early rectal cancer can be avoided by local resection to avoid the risk of postoperative disability caused by radical surgery.

However, neither the NCCN guidelines nor other widely used guidelines at home and abroad believe that local resection is safe only for low-risk Tl stage rectal cancer with good/intermediate differentiation and no lymphatic or vascular invasion, and the resection margin must be at least 1mm. Histological features associated with an increased risk of local recurrence include poor histological differentiation, deep submucosal invasion, lymphatic or vascular invasion, perineural invasion, SM3, and tumor size (pT1&gt; 5cm). Under any high-risk histological characteristics, significantly increased the risk of lymph node metastasis after local excision, tumor prognosis is damaged, need total mesorectum excision. Step guide, colorectal cancer is achieved if the endoscopic cure, need to achieve without vascular/nerve invasion, high/medium differentiation, and no more than 1000(including m submucosal infiltration of such a request. However, JSPEN guidelines suggest that lymph node dissection is necessary for the two characteristics of tumor vertical resection margin and tumor budding. In 2016, Borstlap[et al. proposed a more detailed oncology classification for early rectal cancer for the first time, which separated rectal cancer patients with specific oncology characteristics from the traditional definition of high-risk rectal cancer. It found that patients with early-stage rectal cancer (pTl stage,3-5cm in diameter or less than 3cm with at least one high-risk factor; pT2 stage tumor diameter < 3cm and no high-risk factors) accounted for 75% of locally resected rectal cancers. But for such a high proportion of early in patients with rectal cancer, postoperative NCCN give advice is to choose the traditional adjuvant radiation and chemotherapy or remedial radical resection (chemoradiotherapy, CRT), stereotypes can abandon always shall choose the remedial radical remains to be seen, therefore, The salvage treatment of early rectal cancer classified as intermediate-risk needs further study.

Salvage chemoradiotherapy can achieve the purpose of organ preservation, and the quality of life of patients is significantly better than that of patients undergoing salvage surgery. A surface, based on the research of the national cancer data center T1N0 after local excision of rectal cancer patients with radiation and chemotherapy was 10%, and the T2 local excision of rectal cancer after chemoradiation is as high as 40%, partial resection of additional remedial chemoradiation contrast radical TME surgery three years DFS no statistical differences. However, the absence of lymph node dissection and radiation injury (such as radiation enteritis, perianal pain, etc.) do not make clinicians and patients completely prefer adjuvant chemoradiotherapy. In addition, due to the requirements of quality of life and anxiety of patients, doctors sometimes avoid completing total mesorectal resection (cTME) surgery for intermediate and high-risk tumors and turn to salvage chemoradiotherapy as an alternative. Clinical data to support this strategy are still lacking. As an alternative to organ preservation after local resection, whether adjuvant chemoradiotherapy can be a reliable salvage option remains controversial.

At present, there are great differences in the results of studies on salvage therapy for intermediate-risk rectal cancer patients after local resection. Most of these studies included patients with different local resection platforms and different baseline conditions such as age, gender, and T stage. The local recurrence rate of salvage chemoradiotherapy is as high as 14%, but the patients included in the studies are not strictly in the intermediate-risk group. In 2022, Lin Guole's team reported 110 patients with early rectal cancer who underwent local resection, and they were divided into CRT group and TME group according to the salvage treatment method selected. There was no significant difference in overall survival and disease-free survival between the two groups, and pathological stage pT2 after local resection was the only independent risk factor affecting disease-free survival. The treatment mode of local resection combined with salvage chemoradiotherapy has a good effect on the sexual function and anorectal function of patients. However, limited to a single center and a small sample size, the recurrence problem caused by salvage chemoradiotherapy should still be vigilant. Based on the above problems, we urgently need to ensure that dangerous risk early in patients with rectal cancer after partial resection of oncology result under the condition of reliable to determine a more optimal treatment, for this is a fairly high proportion of patients provide good clinical evidence to choose treatment, and we think, The identified "optimal solution" should strike an optimal balance between treatment-related complication rates and tumor control in early-stage rectal cancer.

In conclusion, we conducted a prospective, randomized, open, multicenter, parallel controlled, non-inferiority clinical trial of curative TME (control group) and salvage chemoradiotherapy (experimental group) in patients with intermediate risk T1 rectal cancer after local resection. This study can provide high-level evidence support for the final choice of these two salvage treatments for intermediate-risk early rectal cancer after local resection. In addition, it can also add a new layer to the personalized and precise treatment of rectal cancer, which will benefit more patients.](streamdown:incomplete-link)

Inclusion Criteria:

1. aged 18-75 years;
2. Local radical resection of rectal adenocarcinoma (TEM, TAMIS, TSPM, EMR, ESD or polypectomy)
3. pT1 with a diameter of 3-5 cm, or a maximum diameter of 3 cm, and at least poor differentiation and/or lymphovascular invasion and/or perineural invasion and/or SM3;
4. The distance from the lower edge of the tumor to the anal verge was within 10cm on MRI at initial diagnosis;
5. clinical stage N0M0 at initial diagnosis;
6. no multiple colorectal cancer;
7. The heart, lung, liver and kidney function can tolerate surgery;
8. Patients and their families were able to understand and willing to participate in this study, and provided written informed consent

Exclusion Criteria:

1. complicated with other malignant tumors or a previous history of malignant tumors;
2. not suitable for subsequent chemoradiotherapy or surgery;
3. a history of inflammatory bowl disease (IBD) or familial adenomatous polyposis (FAP);
4. recently diagnosed with other malignant tumors;
5. ASA physical status ≥ IV and/or ECOG performance status &gt; 2 points;
6. patients with severe liver and kidney function, cardiopulmonary function, coagulation dysfunction or combined with serious underlying diseases can not tolerate surgery;
7. a history of severe mental illness;
8. pregnant or lactating women;
9. Patients with other clinical or laboratory conditions were not considered to be eligible for the study