The incidence of rectal cancer in China is characterized by more low-grade rectal cancer, with about 70% of tumors occurring in the middle and low rectum. At present, there is a certain gap in surgeons’ understanding and knowledge of rectal cancer anal preservation surgery. Although relevant clinical guidelines and treatment norms have been issued at home and abroad, there are still some questions to be considered when performing anus-preserving surgery for middle and low rectal cancer.
1. Correct understanding of the concept of low and middle rectal cancer
Usually, the definition of rectum in classical anatomy is the area within 15 cm from the anus. According to this classification, the rectum is divided into upper rectum (11-15 cm from the anal verge), middle rectum is 6-10 cm, and lower rectal cancer is 0-5 cm. middle and lower rectal cancer refers to tumors occurring in the rectum from the anal verge to 10 cm. Emphasizing the concept of mid-lower rectum has important clinical implications for treatment. Because both international and domestic clinical guidelines have clearly pointed out that the treatment of mid-low rectal cancer requires clinical evaluation and preoperative radiotherapy for locally progressive rectal cancer.
2. Standardized preoperative staging and necessary neoadjuvant treatment
For the treatment of rectal cancer, standardized preoperative staging and necessary neoadjuvant therapy can reduce the difficulty of anus-preserving surgery and local recurrence rate of low and middle rectal cancer. In our clinical work, we found that, from the root analysis, many cases with irregular treatment are not preoperative staging. In particular, standardized preoperative staging is crucial when performing anus-preserving surgery for low- and mid-level rectal cancer. At present, from the international literature, preoperative staging mainly adopts the TNM staging of the American Cancer Society (AJCC). It is internationally recommended to apply MRI of the pelvis and transrectal ultrasound examination of the vulgar spirits system to brag about nettle 6 miscellaneous enjoined plant compulsions to haunt the back of Π Π cT3 (c meaning clinical stage), cT4, or patients with lymph node metastasis should receive preoperative neoadjuvant radiotherapy.
The radiotherapy dose is usually chosen as 45,0~50,4 Gy for 25 times. Chemotherapy is either oral capecitabine or continuous intravenous 5-FU. The benefits of preoperative neoadjuvant radiotherapy have been demonstrated to reduce the rate of local recurrence and increase the chance of anal preservation. Standardized preoperative staging and adjuvant treatment for low and intermediate rectal cancer are important issues facing rectal cancer surgery in China that need to be addressed in a standardized manner. Scientific and standardized preoperative staging and appropriate application of preoperative neoadjuvant therapy can significantly reduce the local recurrence rate and enable patients to benefit from neoadjuvant therapy.
3.Rational selection of anal preservation surgery
Anal preservation surgery has always been an important treatment means to improve patients’ quality of life in the surgery of middle and low rectal cancer. Many patients are also eager to preserve their anus. However, for anal preservation surgery, although a variety of surgical techniques have been reported, including colo-anal anastomosis and other ultra-low anastomosis methods, the key is the preservation of anal sphincter function after anal preservation surgery. For some patients, despite the use of low and especially ultra-low anastomoses, it is a very common clinical situation that the patient has a poor quality of life and poor bowel control after surgery. Therefore, surgeons should be realistic when choosing anus-preserving surgery, and choose it reasonably according to their own operating techniques and the patient’s own characteristics. The difficulties that an unsuccessful anal preservation surgery can bring to the patient’s postoperative life are incalculable. It is disastrous for the patient if the anus is only preserved but not the complete sphincter function, which should be highly valued by the surgeon.
4.Intraoperative points of attention
(1) The problem of distal cutting edge. The key to the surgery of low and middle rectal cancer is to radically reach R0 resection. During the operation, especially for obese male patients, due to the relative narrow pelvis, the exposure of distal incision margin and safe incision margin are very important. A recent Meta-analysis of 7000 patients showed that the difference in local recurrence rate between distal margins >1 cm and ≤1 cm was only 1% and was not statistically significant (P>0.05). Recent literature suggests a change in the importance of the distal margin and its perception for low anal preservation surgery for rectal cancer. More prospective clinical trials are needed to confirm whether the traditional 2 cm safety margin still has real clinical significance.
(2) The importance of the circumferential margin (CRM). In addition to the distal margin, the CRM appears to be of paramount importance in low anal preservation surgery. Preoperative neoadjuvant therapy is recommended for patients with a potentially positive preoperative assessment of CRM. In contrast, postoperative adjuvant chemotherapy is recommended for patients with a positive CRM on postoperative pathological evaluation. In the absence of preoperative neoadjuvant therapy, patients with positive CRM should receive postoperative adjuvant radiotherapy. Therefore, there is a shift in the surgeon’s concept from adequate distal margins to focus on CRM.
5. Prevention and treatment of anterior resection syndrome (ARS)
ARS is an important complication of anus-preserving surgery for low rectal cancer, which refers to some symptoms caused by frequent stool, urgent stool and difficult stool control after anus-preserving surgery, often occurring after anus-preserving surgery for low rectal cancer, and is caused by the loss of rectal pouch function and defecation reflex. The incidence of ARS after anus-preserving surgery for low rectal cancer is high, especially for patients with coloanal anastomosis, the incidence is as high as 30%.
Patients with ARS often have poor quality of life and frequent defecation, which makes patients suffer. For patients undergoing anus-preserving surgery for low to mid-level rectal cancer, especially for patients with low anastomosis or ultra-low anastomosis, effective preoperative doctor-patient communication is very important. First of all, we should fully explain the possible complications of ultra-low anastomosis, including ARS, and obtain the full understanding of patients. In addition, there is no uniform treatment protocol for ARS prevention. For ultra-low colonic anastomosis, colonic storage pouch (CJP) can delay or reduce the symptoms of ARS. The length of the colonic storage pouch does not exceed 5 cm, and the colonic storage pouch can function better for stool control in the first 1-2 years after surgery. There is no uniform quality control standard for complication control of anal preservation surgery. Symptomatic treatment is the main countermeasure. Usually adopted is the regulation of stool through diet, and the use of some drugs is only a stopgap measure.
6.The problem of local excision
In our clinical work, we often encounter some patients who have already undergone local resection of rectal cancer in local hospitals, and the most common points of these surgeries are.
(1) No standardized staging was done before surgery, and local resection was performed for patients when they saw that the tumor was not large or the patient had a strong desire to preserve anus.
(2) Most of the resected pathological specimens were not standardized for labeling, making it impossible for pathologists to determine whether the patient’s margins were clean.
According to the National Comprehensive Cancer Network (NCCN) guidelines and the 2011 edition of the Chinese Colorectal Cancer Diagnosis and Treatment Standards of the former Ministry of Health, local resection of rectal cancer needs to meet the following points.
(1) T1 stage tumor;
(2) Good differentiation;
(3) MRI indicates no enlarged lymph nodes;
(4) Distance from the anus <8 cm;
(5) Tumor diameter < 1/3 of the total length of the intestinal circumference;
(6)The cut margin is >3 mm;
(7) Endoscopically resected polyps with cancerous infiltration, or pathologically indeterminate;
(8) tumor diameter <3 cm.
Thus, it seems that there are strict indications for local resection of rectal cancer. In addition, a common question is how to deal with preoperative evaluation of stage T1 tumor, but postoperative pT2, or positive cut margins? Many surgeons use the approach of extended resection, but in fact the guidelines have clearly stated that such patients should not undergo extended resection because the probability of distant or regional lymph node metastasis is much higher in such patients (especially those with pT2) than in stage T1 tumors. The correct choice is to perform radical rectal cancer surgery.
For low and intermediate rectal cancer, how to choose a reasonable surgical approach should take into account the maximum benefit to the patient, firstly to achieve the goal of radical treatment, and then to consider preserving the function of the anal sphincter. Starting from preoperative staging, standardizing the preoperative treatment and choosing the surgery reasonably will bring benefits to patients with low- and intermediate-level rectal cancer.