This study intends to explore the clinicopathological characteristics and survival prognosis of locally recurrent colorectal cancer patients with different treatment modes by retrospectively analyzing the medical records of locally recurrent colorectal cancer patients who received hospitalization in our center. Transcriptome sequencing and public databases were used to screen for molecular markers related to locally recurrent colorectal cancer and to explore molecular markers' regulatory role in the progression of locally recurrent colorectal cancer.

In the past few decades, although the widespread implementation of total mesorectal excision (TME) and neoadjuvant chemoradiotherapy has dramatically reduced the postoperative local recurrence rate of rectal cancer, local recurrence after radical resection of colorectal cancer still affects the long-term survival of patients. One of the main reasons is that the postoperative local recurrence rate in patients with rectal cancer is about 6-10%, while that in colon cancer is about 4-13%. In clinical practice, surgical treatment is the preferred treatment option for patients with locally recurrent colorectal cancer (LRCRC). However, only more than one-third of LRCRC patients can be surgically resected with recurrent lesions. For surgically treatable LRCRC patients, since the recurrent lesions often infiltrate widely, complete resection of the lesions usually requires expanding the scope of surgical resection, and posterior pelvic surgery is needed if necessary. Surgery (PPE) or even total pelvic excision (TPE), the complications, functional impairment, and perioperative death caused by the surgery also affect the patient's near and far prognosis. When there are distant metastases or unresectable recurrent tumors, radical resection is often not feasible, which may result in significant morbidity and mortality, so it is necessary to explore different treatment modalities, especially surgical treatment. What is the impact on LRCRC. The mechanism of local recurrence is usually thought to be caused by insufficient resection margins or the planting of detached tumor cells. Another standard theory is that it is caused by metachronous canceration around the anastomosis.The possible reasons are unstable cell proliferation and epithelial adaptation at the anastomosis site-sexual hyperplasia. Some studies also believe neither theory can explain the higher recurrence rate around the anastomosis, suggesting that it may be due to unique and persistent genetic changes. By reading a large amount of relevant literature, we found that local recurrence is a kind of metastasis or metachronous metastasis. Metastasis is a complex, multi-step process. Current metastasis research mainly focuses on various cancer cells. However, research on the molecular regulatory mechanisms of colorectal cancer metastasis is still limited.

Inclusion Criteria:

1. Patients with LRCRC who received hospitalization in our center and patients with stage II-III colorectal cancer whose primary surgery was radical surgery
2. The pathological type of primary tumor is adenocarcinoma
3. Postoperative local recurrence of colorectal cancer diagnosed by imaging or pathological examination
4. Have complete medical records and continuous follow-up records

Exclusion Criteria:

1. Familial hereditary colorectal malignant tumors
2. Past history of other malignant tumors
3. Recurrence and diffuse peritoneal recurrence occurring within 1 month after surgery

Patients with locally recurrent colorectal cancer who underwent surgery during hospitalization and whose primary surgical pathology was stage II/III.