As one of the most common tumors in China, colorectal cancer has been on the rise year by year in recent years, and surgical treatment is still the only means of cure. After surgery, surgeons focus on 1) reducing the risk of recurrence and metastasis, 2) promoting the recovery of patients with colorectal cancer, and 3) doing a good job of patient follow-up and review. Next, we will talk about the surgeon’s “three axes” from the above three perspectives! Adjuvant therapy for colorectal cancer Postoperative adjuvant therapy for colorectal cancer includes adjuvant chemotherapy and adjuvant radiotherapy. The ultimate goal of adjuvant therapy is to eliminate the remaining tiny metastatic lesions, reduce the chance of tumor recurrence and metastasis, and improve the cure rate. Adjuvant chemotherapy Surgery is the only radical treatment for stage I-III colorectal cancer, but 35%-50% of the patients still have tumor recurrence after radical surgery. A large number of clinical studies have confirmed that adjuvant chemotherapy with 5-fluorouracil alone combined with the sensitizer calcium folinate after radical surgery can reduce the risk of early recurrence of colorectal cancer by about 40%, and improve the overall survival rate by about 7%. Meanwhile, studies have also confirmed that oral fluorouracil analogs (e.g., capecitabine) are equivalent to intravenous 5-fluorouracil, and capecitabine is becoming more and more widely used in clinical applications due to its convenient administration and good tolerability. On the basis of single-agent fluorouracil-based therapy, two-agent chemotherapy in combination with oxaliplatin can further increase the overall survival rate by 3.0%. Therefore, adjuvant chemotherapy after radical surgery for colon cancer can effectively reduce the recurrence rate and prolong the overall survival of patients. However, not all colon cancer patients need to receive adjuvant chemotherapy after radical surgery! Stage I colon cancer has early tumor stage and high cure rate, and the 5-year survival rate of patients who receive radical surgery alone is more than 90%, therefore, adjuvant chemotherapy is not recommended; Stage IV colon cancer, except for a small portion of patients with resectable liver and/or lung metastases, about 85% of patients lose the opportunity to receive radical surgery, and this group of patients receives palliative chemotherapy, which does not meet the definition of adjuvant chemotherapy. Therefore, the indications for adjuvant chemotherapy are limited to patients with stage II and III colon cancer. Adjuvant chemotherapy is recommended for all patients with stage III colon cancer, and it is controversial whether patients with stage II colon cancer should receive adjuvant chemotherapy, and it is currently recommended that stage II colon cancer patients be divided into two categories according to whether they are combined with high-risk risk factors for recurrence: high-risk II and non-high-risk II. Adjuvant chemotherapy is recommended for patients with high-risk factors, and it is recommended that patients with non-high-risk factors should be followed up with observations or be given a single agent of fluorouracil, which is the most effective way to prevent the recurrence of the disease. Adjuvant chemotherapy with single-agent fluorouracil analogs, including 5-fluorouracil monotherapy combined with calcium folinic acid or capecitabine. According to the “Diagnostic and Treatment Criteria for Colorectal Cancer” of China’s Health and Family Planning Commission, high-risk factors include: 1) poor histological differentiation (grade III or IV); 2) T4 stage in TNM; 3) invasion of blood vessels and/or lymphatic vessels; 4) combined with intestinal obstruction and/or intestinal perforation prior to surgery; 5) insufficient lymph nodes detected in the surgical resection specimen (fewer than 12); 6) insufficient lymph nodes detected in the surgical resection specimen (fewer than 12); 7) insufficient lymph node detection (fewer than 12); 8) insufficient lymph node detection (fewer than 12); 9) lack of lymph nodes (fewer than 12). In the National Comprehensive Cancer Network (NCCN) guidelines, risk factors for stage II colon cancer also include tumor invasion of nerves, positive tumor margins, suspicious positive margins, or margins too close to the tumor. Adjuvant Radiation Therapy In colon cancer, radiation therapy is generally not administered after surgery unless there is clear tumor invasion of a local organ. As for rectal cancer, because even with radical surgery, the local recurrence rate can still be as high as 20-30%. Especially for rectal cancer in the middle and lower segments, the tumor is usually located below the peritoneal reflex, and due to the special anatomical structure of the rectum, radiotherapy has become an important part of the comprehensive treatment in the perioperative period. Therefore, the current NCCN guidelines recommend that adjuvant radiotherapy should be considered if the postoperative pathological stage is T3 or above or lymph node metastasis (+). Although most clinical studies of adjuvant radiotherapy for rectal cancer have shown that radiotherapy does not significantly prolong the survival time of patients, it can significantly reduce the risk of local recurrence to 5-7%. Therefore, if there is no obvious contraindication to radiotherapy or the patient explicitly refuses, radiotherapy should be given to the primary foci for both stage II and III rectal cancer. In addition, with the rapid development of medical imaging, pelvic enhancement MRI and endorectal ultrasound can be more and more accurate for preoperative staging, therefore, for preoperative diagnosis of T3/T4 or N+ rectal cancer, the current international guideline advocates preoperative neoadjuvant radiotherapy. However, due to the varying medical standards and cultural differences in China, it will take time to fully promote preoperative neoadjuvant radiotherapy for low and intermediate rectal cancer. Microsatellite Instability (MSI) and DNA Mismatch Repair (MMR): In stage II colorectal cancer, MSI and MMR status have been found to be associated with colorectal cancer prognosis. Patients with high microsatellite instability (MSI-H) and/or mismatch repair deficiency (d-MMR) have a better prognosis and are thought not to benefit from adjuvant chemotherapy with 5-FU alone. However, current evidence suggests that the benefit of oxaliplatin in combination with 5-FU adjuvant chemotherapy is not affected by MSI and MMR status. Therefore, the NCCN guideline recommends that all patients with stage II colorectal cancer should be tested for MSI or MMR status of tumor tissue specimens, and single-agent adjuvant chemotherapy with fluorouracil analogs is not recommended if MSI-H or dMMR. China’s Health and Family Planning Commission’s “Colorectal Cancer Diagnostic and Treatment Guidelines” considers that MSI and MMR tests have not been popularized in China yet, so it is recommended that those who have the conditions should test the MMR or MSI status of the tissue specimens, and if it is dMMR or MSI-H, single-agent adjuvant chemotherapy with fluorouracil-based drugs is not recommended. Adjuvant Treatment Considerations The timing of the initiation of adjuvant chemotherapy is not clearly defined; in principle, it can be initiated when the patient’s physical condition can tolerate it, most often 4-8 weeks after radical surgery; the entire time frame for adjuvant therapy usually does not exceed 6 months. Elderly colon cancer patients >70 years of age and other patients with complex concomitant diseases should be given combination chemotherapy, single-agent fluorouracil-based chemotherapy, or regular follow-up under the guidance and close monitoring of a specialist. Currently, irinotecan (CPT-11), the molecularly-targeted agent bevacizumab (bevacizumab), and cetuximab (cetuxan) are not recommended as adjuvant therapy for patients with high-risk stage II and stage III colorectal cancer. In addition, local radiotherapy should also be performed at an elective stage if radiotherapy is not performed before surgery for low and intermediate rectal cancer, and in principle, adjuvant radiotherapy should be started within 3 months after surgery. Oral capecitabine and 5-Fu sensitization may be considered in conjunction with radiotherapy. Overall, adjuvant therapy has been shown to reduce the risk of local recurrence and distant metastasis of colorectal cancer and prolong overall survival. However, for each individual patient should also be guided by a multidisciplinary team to design a reasonable comprehensive management plan after comprehensively evaluating the benefits and risks of patients receiving adjuvant radiotherapy. Rehabilitation of colorectal cancer The postoperative rehabilitation of colorectal cancer patients mainly includes physiological rehabilitation and psychological rehabilitation. Physiological As the patient’s digestive tract anatomy is permanently changed, eating and defecation habits are significantly changed. For example, adhesive intestinal obstruction is prone to occur within 6 months after surgery, so usually the diet is based on nutritionally balanced and easily digestible food as much as possible. In addition, due to partial resection of the large intestine, many patients experience thinner and more frequent bowel movements, while some may experience alternating diarrhea and constipation as the peristaltic function of the intestines has not yet fully recovered. The vast majority of patients will return to normal eating and bowel habits within one year. In addition, some patients may have a temporary or permanent stoma in the abdomen according to the needs of their condition. Replacement of the stoma bag and routine care of the stoma is an important part of smooth recovery after surgery. Patients and their families should learn how to change the stoma bag, take care of the stoma and the skin around the stoma, and observe the situation of gas and defecation under the guidance of a professional stomatologist. Patients undergoing postoperative adjuvant radiotherapy should also pay attention to related digestive tract reactions during treatment. If there is significant weight loss, loss of appetite, fatigue or severe diarrhea during the treatment, the treatment should be suspended, and timely communication with the oncologist to adjust the treatment plan and dosage, as well as to strengthen the supportive therapy. Psychological aspects When patients learn that they are suffering from malignant tumors, the psychological blow is huge, and there may be irritability, anxiety, insomnia, depression, frustration and other adverse emotions. In addition to the support and encouragement given by family members, it is also necessary to ask professionals to conduct psychological counseling and psychological detachment at the right time. Psychologists can help patients correctly vent their bad emotions through counseling, physical or pharmaceutical means, which can help increase patients’ confidence in curing the disease and help them cooperate with doctors to carry out anti-tumor treatment more actively. In particular, we should pay attention to the patients who fail to retain the function of the anus because of their condition. Artificial anus (stoma) will have a great impact on the patient’s spirit and normal life after surgery. The understanding and support of family and friends, the professional services of psychologists, and the correct guidance of medical staff are all helpful in alleviating the embarrassment and low self-esteem caused by the stoma. On top of that, mutual help meetings and timely communication among patients will also relieve their mental pressure and negative emotions. Finally, correctly guiding patients’ postoperative lifestyle habits is also an indispensable part of physical and mental recovery. This includes: smoking cessation, weight control, moderate exercise, dietary changes (reducing the intake of red meat and refined meat, increasing the intake of vegetables, fruits, fish and white meat) and so on. Follow-up of colorectal cancer Several large-scale clinical studies have shown that after radical surgery, 80% of recurrent metastasis occurs within 3 years after surgery, and 95% of recurrent metastasis occurs within 5 years after surgery. Therefore, regular and standardized postoperative follow-up can help to detect recurrent metastatic lesions in time and provide the possibility of reoperation for radical treatment or long-term survival with tumor. Currently, according to the NCCN guidelines, patients with stage I colorectal cancer should have a follow-up colonoscopy at 1 year and 3 years after surgery, and then have a follow-up colonoscopy every 5 years. If adenomas are found on routine examination (e.g., choriocarpous polyps, polyps larger than 1 CM, or high-grade atypical hyperplasia) both should be reviewed at 1 year. Stage II and III patients should usually have chest CT and abdominopelvic enhancement CT or MRI and CEA at 4-6 weeks postoperatively, and then every 3-6 months for 2 years after surgery. The above examinations can be completed every 6 months or so from year 3 to year 5, and should be repeated annually after 5 years. The frequency of colonoscopy can refer to the follow-up requirements for stage I patients. However, special attention should be paid to the fact that if the patient has not completed a complete colonoscopy before the operation due to intestinal obstruction or other reasons, colonoscopy should be performed about 6 months after the operation if there are no special circumstances. In addition, according to the available evidence-based medical evidence, PET-CT is not yet supported as a means of regular postoperative imaging. However, if the patient’s CEA level is persistently and progressively elevated on postoperative review and there are no positive findings on enhanced CT and/or MRI, PET-CT may be considered to look for recurrent metastatic foci. Or when recurrent or metastatic lesions are present and help is needed to determine whether the lesions are isolated and whether re-surgery is possible, PET-CT may be considered to help with the overall picture of the disease.