Rectal cancer is one of the common malignant tumors in China, and its incidence is increasing year by year, which seriously threatens people’s health and life. With the rapid development of anatomic pathology, oncology, molecular biology, immunology and surgical instruments, the number of various anus-preserving procedures for rectal cancer has increased year by year. In view of the vast geographical area of China, the medical conditions in different regions vary greatly, and the development of surgical technology is also unbalanced, so the selection and philosophy of surgical indications are different, and the postoperative results vary. In fact, the choice of anus-preserving surgery and the quality of surgery are closely related to the local incidence rate, long-term survival rate, quality of life, and prognosis. Therefore, it is crucial to continuously strengthen the standardization of surgical treatment of rectal cancer to improve the level of surgical treatment of rectal cancer [1].
I. Principles to be followed in the selection of rectal cancer anus-preserving surgery
The principles that must be followed for rectal cancer anal preservation surgery are: first, the radicality of tumor resection and the thoroughness of lymph node dissection, and second, the preservation of physiological function and improvement of life quality. (1) The principle of total mesorectal excision (TME) is emphasized, and the technique requires a sharp separation under direct vision along the loose natural space between the pelvic fascia and the wall, complete removal of lymph, blood vessels, fat and fibrous connective tissue around the rectum, and a distal mesorectal excision length of 5 CM from the tumor margin and a distal rectal wall margin of more than 2 CM. Heald proposed the new concept of total mesorectal excision (TME), which reduced the postoperative local recurrence rate from 20-45% to less than 10%, and in recent years [2] reported 405 cases of TME, with a five-year recurrence rate of only 3% and a survival rate of 80%, showing good results. Therefore, TME is currently recognized as the gold standard and principle that must be followed for radical surgical resection of rectal cancer. (2) Emphasis is placed on following the resection of the lower margin of the cancer foci after rectal freeing greater than 2 cm, and ensuring the negative margins of the distal bowel segment, including the negative circumferential margins, to avoid the residual cancer cells leading to local recurrence. (3) Emphasize following the tumor-free operation technique to reduce cancer cell shedding and implantation in order to reduce the local recurrence rate after surgery. (4) Emphasize following the preservation of anal defecation control function and physiological function to improve the quality of life; normal defecation function relies on sound sphincter function and complete sensory reflex function, and the complete anorectal ring must be preserved without either [3]. (5) It is emphasized that adherence to the correct and reasonable selection of surgical indications should not be based on individual subjective wishes, but must pay attention to objective conditions and individualize the selection according to the specific conditions of each patient.
Individualized selection principles of anus-preserving surgery for rectal cancer
The best curative effect can be achieved only when the correct and reasonable selection of surgical style is made [3]. In principle, if the rectal cancer is more than 5 cm from the anal verge and the differentiated adenocarcinoma is better, the anus-preserving surgery should be selected; for rectal cancer less than 5 cm from the anal opening and poorly differentiated mucinous carcinoma, Milse surgery should be the main procedure. At present, there are more anal preservation surgeries and different methods. Anal preservation surgery reaches 70% in larger hospitals [4].
1. low anterior resection and low anterior resector anastomosis It is more suitable for low to medium rectal cancer that is more than 6 CM from the dentate line. Since the distal 2-3 CM intestinal segment of the cancer is removed, more than 2 CM of the terminal rectal segment can still be retained for anastomosis, and the anastomosis is located at the level above the anorectal ring after surgery. The frequently used surgical procedures: (1), low anterior resection (LAR) or Dixon procedure. This procedure is suitable for patients with rectal cancer with relatively wide pelvic cavity. (2), low anterior resection anastomosis. As early as 1980, Knight proposed that for some low pelvic narrow cavity, the difficulty of revealing the operative field and the difficulty of manipulating the anastomosis become simpler and more time-saving, and the postoperative anastomotic leakage is 3.4%, which is much lower than the 10% of surgical method suture. This procedure is suitable for rectal cancer patients with narrow pelvic cavity, Dixon’s operation or low anterior resector anastomosis, because the defecation nerve reflex of rectal mucosa and the complete anal rectal ring are preserved, therefore, the patients can maintain the near normal anal defecation and exhaust function after the operation, which is considered as the ideal radical anal preservation procedure for low and middle rectal cancer.
2.Modified Bacen operation Transabdominal rectal drag-out resection anastomosis. It is more suitable for cases in which the anus-preserving anastomosis of low-level apparatus fails, and the rectum is dragged out through the abdomen for anal anastomosis. However, because the function of the anal sphincter is not very satisfactory after this operation, the stool control function is poor, and there are many complications of the operation, so the operation is limited in recent years.
3.Parks procedure[5] is suitable for low rectal cancer within 4-6 cm from the dentate line. It is mainly suitable for those who cannot perform the Dixon procedure or anastomosis, but the Parks procedure leads to a drastic reduction of fecal storage function, resulting in poor control of early defecation. Parks procedure was implemented in the clinic for a while, but the incidence of anastomotic fistula after Parks procedure is high, which requires routine abdominal colostomy, causing inconvenience to patients and economic burden of re-operation.
4.Triple anastomosis method is suitable for patients with low rectal cancer within 4-6 cm from the dentate line. (1) Triple anastomosis method On the basis of double anastomosis, a linear cutting suture is used to complete the formation of the colonic reservoir pouch, and then the reservoir pouch is anastomosed with the anal canal. This procedure can improve the early postoperative bowel control function significantly and improve the quality of life of patients. (2) Kaito is a new type of cutting and suturing device recently introduced, which can complete the distal rectal closure and cutting in one time, making the operation more convenient and time-saving, and making it possible to preserve the anus for ultra-low rectal cancer, providing a new weapon for ultra-low rectal cancer anus preservation surgery. Generally speaking, as long as the distal end of the tumor is free from the intestinal canal for more than 3-4cm, both Kaito cutting and closing device can be used to complete the ultra-low anastomosis successfully, which is the best choice at present.
5.Transanal ramus pathway (Mason) surgery For ultra-low rectal cancer within 2-5 cm from the dentate line or less than 5 cm from the anal verge: the indications are rectal tubular adenoma, villous tubular adenoma and adenoma carcinoma or earlier rectal cancer T1NOMO. Qiu Huizhong et al [6] reported 85 cases of Mason’s operation, and no anal sagittal occurred after the operation, with a 5-year survival rate of 95.5% and very satisfactory results.
Intersphincteric resection (ISR) is suitable for early rectal cancer (T1 or partial T2) within 2 cm-5 cm from the dentate line and can achieve complete resection of the tumor and satisfactory bowel control function[7] . Saito et al[9] reported a 5-year survival rate of 91.5% and good postoperative bowel control of 93%.ISR surgery can save approximately one-third of patients with early rectal cancer within 2cm-5cm of the dentate line who would have undergone Miles surgery according to the original criteria, avoiding the sacrifice of the anus [10].
7. Li Shiyang et al. sleeve-in anastomosis for anal preservation is suitable for patients with low-grade rectal cancer within 4-6 cm from the dentate line. This method can effectively strengthen the anastomosis, reduce tension, and decrease the incidence of anastomotic leakage, which not only preserves the integrity of the anorectal ring and the skin of the anal canal, making the postoperative anal defecation control function close to normal, but also preserves the physiological function of the patient and improves the quality of life. In recent years, Li Shiyang et al [11] reported 231 cases of anastomotic anus-preserving surgery with anastomotic leakage of 2.9% and local recurrence rate of 3.7%, with good efficacy, which may become one of the safe and effective anus-preserving procedures for low rectal cancer.
8.TEM surgery (transanal endoscopic microsurgery, TEM) was first reported by G. Buess of Germany in 1983. It is suitable for the therapeutic method of middle and upper rectal broad-based adenoma and part of PT1 stage rectal cancer and the palliative treatment of small part of PT2 stage rectal cancer. In China, Xia Lijian et al [12] were the first to report 40 cases in 2007 and obtained satisfactory results.
9.Laparoscopic radical anus-preserving surgery for mid-low rectal cancer[13] is suitable for patients with mid-low rectal cancer. This procedure was carried out in the mid-1990s. The biggest advantage of this procedure is that it provides surgeons with a large operating space with minimal surgical incisions, and is characterized by less trauma, less bleeding and faster recovery.
10. Principles of choosing anus-preserving surgery after preoperative neoadjuvant radiotherapy The use of neoadjuvant radiotherapy can shrink the tumor, achieve the descending stage and improve the rate of anus preservation for preoperative rectal cancer with unresectable T3 or T4 stage tumor. Yu Baoming [14] reported a group of 105 cases of T3 and T4 rectal cancer, in which the preoperative radiotherapy was used to shrink the mass and achieve the descending stage. With a 6-week break for surgery, 95.6% of the patients were successfully performed anus-preserving surgery, a result that changed the traditional treatment concept and was encouraging for improving the resection and anus-preserving rates.
4. How to choose the function-preserving surgery for low rectal cancer
As we all know, while pursuing complete surgical resection to improve surgical efficacy, it is important to pay more attention to the preservation of physiological functions to improve patients’ quality of life. It is inevitable to sacrifice part of the fecal storage potbelly and rectal mucosal defecation nerve return system during radical resection and anal preservation surgery for low or ultra-low rectal cancer, and to damage the anal ramus muscle for a short period of time due to excessive anal dilation [11]. Therefore, reconstruction of the rectal pouch is very important to improve the stool storage and restore the anal defecation function after rectal cancer surgery.
1.Colonic pouch forming At present, there are two types of surgery commonly used, (1) colonic J-shaped pouch using the lack of dipping sprite ampoule mountain Bali any choking leisure J-shaped pouch, in the use of anastomosis to complete the top of the pouch and the distal rectum end-end anastomosis, the operation is suitable for the sigmoid colon is relatively long. (2) The colonic pouch is formed 3-4 cm from the distal end of the colon to 8 cm from the proximal end of the colon, then sutured transversely, and the end of the colon is anastomosed with the stump of the rectum with an anastomosis. On the whole, colonic J-type storage bag and colonic formation storage bag have similar effects on improving anal bowel control function after rectal cancer preservation surgery, but the length of the storage bag is generally 5 cm.
2.Procedure to preserve pelvic autonomic nerves TME and lateral lymph node dissection during radical resection of rectal cancer, the expansion of the surgical scope inevitably damages the pelvic autonomic nervous system, leading to bladder dysfunction and sexual dysfunction after surgery. Back in the 1990s, Japanese scholars actively advocated routine lateral lymph node dissection during radical resection for rectal cancer [ 15]. However, most of the scholars in Western countries are against it because of the high surgical trauma, bleeding, long operation time and high morbidity rate. The main disadvantage is the damage to autonomic nerves leading to urinary and sexual dysfunction, which significantly reduces the quality of life of patients, but lateral lymph node dissection can reduce the pelvic recurrence rate after middle and lower rectal cancer surgery. Given that the incidence of urinary dysfunction after lateral lymph node dissection is as high as 70%, complete or partial erectile dysfunction occurs in 25%-100% of male patients, and loss of ejaculatory function reaches 19%-59%[16,17] . In recent years, due to in-depth studies on the distribution of autonomic nerve initiation in rectal and pelvic anatomy, Japanese scholars have proposed a new concept of preserving the autonomic nerve. While ensuring radical resection of the cancer, the autonomic nerve is preserved in order to achieve preservation of urinary and sexual functions. Depending on the extent of lymph node metastasis and infiltration of individual patients and the different sites of lymph node invasion for selecting different surgical procedures, complete preservation of the pelvic autonomic nerve and partial preservation of the pelvic autonomic nerve, such as preservation of the unilateral autonomic nerve and preservation of the sacral 4 pelvic visceral nerve, can be chosen. This can effectively preserve the voiding function and sexual function, which can significantly reduce the incidence of postoperative complications, resulting in a significant improvement in voiding function and sexual function by decreasing the postoperative voiding dysfunction from 65%, to 16%, increasing erectile function from 34% to 92%, and increasing ejaculation from 0% to 83% [18, 19, 20]. In China, Dong Xinshu et al. reported 124 cases of lateral lymph node dissection preserving the pelvic autonomic nerve with anal preservation, and after surgery, 90. 3% had normal urinary function, 62.3% had erectile function, 57.1% had normal sexual function, and the 5-year survival rate was 61.2%. Therefore, the surgery of preserving the autonomic nerve as much as possible when radical resection of rectal cancer to preserve the anus has been widely paid attention to.
At present, radical surgery for rectal cancer is gradually standardized, and emphasis should be placed on the correct selection of surgical indications and the reasonable selection of anus-preserving surgery; that is, to achieve radical resection of the tumor, reduce the local recurrence rate and improve the 5-year survival rate, and to preserve the function so that the patient can obtain good physiological function and high quality of life, which is the direction and the goal to be achieved by our surgeons’ joint efforts.