Rectal cancer is one of the most common malignancies in Western countries, accounting for approximately 5% of adult patients with malignancies, and its incidence rate is in the 5th place of malignancies. There are about 140,000 new cases of rectal cancer in Europe every year, and the fastest increasing incidence rates in the world are in Eastern Europe and Japan. In recent years, the incidence and mortality rate of colorectal cancer in China are also on the rise, and it is estimated that there are no less than 100,000 new cases of rectal cancer each year.
In the past 30 years, with the development of social economy and medical science and technology, the surgical treatment of rectal cancer has made great progress. First of all, in terms of concept, the ultimate goal is to save the patient’s life by curing the tumor, but it has been changed to strive to eliminate the tumor completely, preserve the function and improve the patient’s quality of life; secondly, there are obvious changes in surgical methods and surgical techniques, such as anus-preserving surgery, total rectal mesorectal resection and minimally invasive surgery are being emphasized and promoted; again, the multidisciplinary comprehensive treatment mainly based on surgery has gained Chemotherapy and radiotherapy have become indispensable adjuvant treatment methods for rectal cancer surgery, and have achieved obvious results.
I. New milestone – total mesorectal excision (TME)
In 1908, British Dr. Miles WE designed the radical abdominal perineal combined rectal cancer resection according to the characteristics of lymphatic drainage of rectal cancer into upper, middle and lower paths, and achieved success, which was later called Miles surgery. This procedure is the first milestone in the surgical treatment of rectal cancer and has been the gold standard surgery for rectal cancer for decades. In 1939, Dixon proposed anterior resection, which gave hope to patients. However, the local recurrence rate of both Miles’ surgery and anus-preserving surgery (Dixon’s surgery) was quite high. 1982, Dr. Heald RJ in England first proposed the concept of TME. He believed that the main reason for local recurrence of rectal cancer after surgery is inappropriate rectal mesenteric resection, and TME can achieve complete resection of rectal cancer and minimize the local recurrence rate. Its surgical feature is to sharply separate the gap between the pelvic visceral layer and the wall layer, straight to the level of the levator muscle, and remove all the visceral fascia and the encircling perirectal fat, blood vessels and lymphatic vessels, the so-called rectal mesentery. In 1992, Dr. Heald RJ reported a local recurrence rate of only 2.6% in 152 patients with rectal cancer after resection according to the TME principle, and in 1997, Heald et al [2] again reported a local recurrence rate of 6% in patients with low rectal cancer after surgical resection according to the TME principle, compared with 29% in those who did not undergo TME. In Germany, Barabouti et al [3] compared 1581 patients with rectal cancer resected according to the TME principle with those without TME and showed local recurrence rates of 9.8% and 39.4% (P<0.0001) and 5-year survival rates of 71% and 50% (P<0.0001), respectively. In addition, TME surgery resulted in a significant improvement in the urogenital function of patients after surgery. Although the incidence of anastomotic fistula was once as high as 20% in the early days of TME, and colostomy was often required to prevent the occurrence of anastomotic fistula, in fact, TME has been increasingly accepted by surgeons as the gold standard of rectal cancer surgery. Therefore, TME has been hailed as a new milestone in the surgical treatment of rectal cancer.
II. New understanding – the re-conceptualization of the lower incisional margin
In 1939, Dixon proposed anterior resection to enable patients to preserve the anus, but how much resection of the distal rectal tumor is considered complete, safe and will not recur has been the focus of attention. 1948, Black proposed that at least 2 cm should be resected; in 1951, Goligher proposed the 5 cm rule; in 1983, Williams proposed that the 5 cm In 1983, Williams suggested that the 5 cm rule was inappropriate and that 2.5 cm was sufficient; later, Madsen, Shirouzu, and Andreola all suggested that 1 cm was sufficient for resection.
How many centimeters of safe subcutaneous margin is appropriate? Scholars from the Cancer Hospital of Sun Yat-sen University conducted an in-depth study on the spread of rectal cancer within the distal intestinal wall. In 2009, Prof. Wong WD introduced the re-understanding of the lower incisional margin in the United States, and believed that a 1 cm lower incisional margin is acceptable after preoperative radiotherapy, and a longer lower incisional margin is not helpful to reduce local recurrence. did not help to reduce local recurrence; however, if the undercutting margin was <8 mm, the local recurrence rate of postoperative patients was as high as 12.6%. Therefore, an inferior incision margin of 2 cm is generally sufficient for rectal cancer, and 1 cm is also acceptable after preoperative radiotherapy. In this way, patients with middle and lower rectal cancer have more chances to preserve the anus.
III. New concept – circumferential resection margin ( circumferentialresection margin, CRM)
In 1986, Quirke et al. first noticed the importance of CRM on local recurrence of rectal cancer, and they pointed out that patients with positive CRM had a high rate of postoperative local recurrence of rectal cancer. This view was later confirmed by many studies, such as Nagtegaal et al [7] in 2002, who reported the prognosis of 656 patients with rectal cancer undergoing TME, with local recurrence rates of 16.0% and 5.8% for patients with CRM <2 mm versus ≥2 mm, respectively (P<0. 0001).
The rate of positive CRM was inconsistently reported across studies, ranging from approximately 4% to 28%, depending on whether the surgeon collaborated with the pathologist and whether the examination was meticulous. Neoadjuvant treatment (radiotherapy or radiochemotherapy) helps to reduce the positive rate of CRM, but short courses of high-dose radiotherapy (5 Gy/dose × 5) do not reduce the positive rate of CRM, while conventional preoperative radiotherapy (45 Gy) or radiochemotherapy (45 Gy + fluorouracil and calcium folinate) have the potential to reduce the positive rate of CRM [8].
CRM detection has important clinical significance, in addition to predicting the prognosis of patients, it can also be used to evaluate the effect of neoadjuvant therapy; if CRM is still positive after neoadjuvant therapy, it indicates poor efficacy and poor prognosis of neoadjuvant therapy. CRM can also guide postoperative adjuvant therapy, and if CRM is positive, additional radiotherapy is appropriate after surgery.
IV. New technology – minimally invasive surgery
The concept of minimally invasive surgery originates from laparoscopic surgery. As part of minimally invasive surgery, minimally invasive surgery is not only about “small incision”, but also about less trauma, better stability of internal environment, more accurate surgical results and shorter hospital stay than conventional surgery. Minimally invasive surgery for rectal cancer includes endoscopic resection, laparoscopic resection of rectal cancer, transanal endoscopic microsurgery, and da Vinci robotic surgery.
1.Endoscopic resection: endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) is mainly performed for patients with pre-cancerous rectal disease and Tis stage rectal cancer. the whole resection rate of EMR and ESD can reach 73.3%-98.6% [9], and the patients recover quickly after surgery and the anal function is preserved good. However, there are preoperative staging difficulties, as the rate of lymph node metastasis in stage T1 rectal cancer is also as high as 29% [10]. In addition, ESD has high technical requirements and is prone to serious complications such as bleeding and perforation, so this procedure should be chosen with great caution.
2, laparoscopic rectal cancer resection: in 1990, Jacobs M completed the first laparoscopic-assisted right hemicolectomy and rectal resection in the U.S. In 1991, Uddo J completed the first total laparoscopic right hemicolectomy in the U.S. In 2004, the U.S. COST trial and in 2002, Lacy et al. reported the results of two randomized clinical trials for colon cancer to compare the results of laparoscopic surgery with those of open surgery. The results both showed no difference in local recurrence rates, complication rates, or overall survival between the two, and concluded that laparoscopic surgery could be an alternative to open surgery. It is worth noting, however, that both randomized trials were in patients with colon cancer, and in particular, the COST trial was limited to right- or left-sided colon resections and did not include patients with transverse colon and rectal cancers.
Although laparoscopic resection of rectal cancer was not recommended by the National Comprehensive Cancer Network Clinical Practice Guidelines for Rectal Cancer (4th edition) until 2011, laparoscopic TME has been performed in many units nationally and internationally.Leroy et al [11] reported the results of a prospective study in which laparoscopic TME was performed in 102 consecutive cases, with a mean tumor distance of 9.16 cm from the anal verge and a median follow-up time of 36 months, a recurrence rate of 6%, and a 5-year survival rate of 75% after radical surgery, which is not inferior to open surgery. However, there is a lack of data from randomized studies with large samples to date. Laparoscopic resection of rectal cancer has its advantages, such as no need for dissection, rapid postoperative recovery of patients, mild pain, reduction of postoperative intestinal adhesions, shortened hospital stay, reduced hospital costs and increased cosmetic results, but it is also limited by the high technical requirements, long learning curve, lack of palpation, and still certain complications, and its long-term results need to be further observed.
Laparoscopic surgery itself is evolving, from multi-hole (three- or four-hole) to single-hole or even without poking holes through the skin of the abdomen, through the natural orifice of the body to complete the surgical operation, the so-called natural orifce transluminal endoscopic surgery (NOTES). This is a fascinating and mysterious technique, and whether it can be promoted is a matter of opinion.
3.Transanal endoscopic microsurgery (transansal endoscopic microsurgery, TEM): TEM is a new minimally invasive technique for the treatment of rectal tumors, which was first reported by Buess in Germany in 1984. This technique is different from other endoscopic techniques in that it is less invasive, and incision, hemostasis, ligation and suturing can be done via endoscopy. Its characteristics are.
(1) The visual image is obtained from an advanced body optic binocular that provides a much improved depth of field of view.
(2) The equipment is specially designed so that instrument insertion and manipulation are performed in parallel planes, clearly distinguishing it from laparoscopic surgery.
(3) TEM can treat higher sites of adenomas and selected early rectal tumors that cannot be reached by conventional instruments. tEM has been clinically used for more than a decade, and it is safe (complication rate of 4.3%) and effective (recurrence rate of 7%) for resection of benign lesions and early tumors of the rectum and low sigmoid colon.
4.Robotic surgery: The da Vinci robotic surgery system has clear images, convenient and accurate operation, and can – remote operation, and is now used in urology, obstetrics and gynecology, cardiothoracic surgery, general surgery, etc. The da Vinci robot-assisted colorectal cancer surgery has been applied in many countries. Choi et al. in Korea used the da Vinci robot to operate on 50 consecutive cases of colorectal cancer patients, including 40 cases of low rectal cancer, with no surgical deaths and no patients transferred to open surgery, with an average clearance of 20 lymph nodes/case, an anastomotic fistula incidence of 8.3%, and a positive CRM rate of 2%. Although the da Vinci robot was invented only 10 years ago, it has already been recognized by surgeons and widely used. In addition to the above advantages, its short learning curve, which can be mastered in a short time by surgeons without basic laparoscopic surgery, is better than laparoscopic surgery. However, due to the small number of cases used in colorectal cancer surgery, short follow-up time and the lack of evidence-based prospective randomized studies, it is difficult to draw conclusions on its evaluation.
V. New model – multidisciplinary comprehensive treatment
In the past 30 years, the treatment of rectal cancer has moved from single surgery to integrated multidisciplinary treatment, and has achieved significant results. For rectal cancer, in addition to surgery, multidisciplinary comprehensive treatment also includes preoperative radiotherapy or radiotherapy and postoperative adjuvant radiotherapy or radiotherapy. The Colorectal Cancer Collaborative Group pooled 22 randomized trials for Meta-analysis, including 14 trials of preoperative radiotherapy with 6350 cases and 8 trials of postoperative radiotherapy with 2157 cases. The results showed that local recurrence rates were significantly reduced in those treated with radiotherapy (either preoperatively or postoperatively) (P<0.05), but 5- and 10-year survival rates did not improve. The results of a randomized clinical trial in the Netherlands showed local recurrence rates of 2% and 8% for those treated with preoperative radiotherapy plus TME and TME alone, respectively. The advantages of concurrent chemotherapy with preoperative or postoperative radiotherapy include local radiotherapy sensitization, reduction of local recurrence and systemic tumor control (i.e., eradication of micro-metastases), and the potential for increased pathologic complete remission (pCR) and anus preservation rates with preoperative radiotherapy. (radiotherapy plus fluorouracil and calcium folinate) versus radiotherapy alone had a pCR of 11.4% and 3.6% (P<0.05), respectively, and local recurrence rates of 8.1% and 16.50/0 (P<0.05), respectively, but the differences in overall survival and anal preservation rates between the two groups were not statistically significant (P>0.05). The German Rectal Cancer Study Group conducted a large prospective randomized controlled clinical trial to compare the efficacy of preoperative and postoperative concurrent radiotherapy for stage II and III rectal cancer. The results showed that the local recurrence rates were 6% and 13% for those treated with preoperative and postoperative radiotherapy, respectively (P=0.006), and the incidence of treatment-related toxicities was 27% and 49%, respectively (P=0.001), but the overall survival and disease-free survival rates were similar in both groups. To date, there is a consensus that adjuvant radiotherapy can improve the efficacy of surgical treatment for rectal cancer, but whether preoperative or postoperative is superior has not been fully determined, but most scholars believe that preoperative radiotherapy is more advantageous. Although preoperative radiotherapy and postoperative adjuvant chemotherapy are increasingly used in clinical practice, there are still many controversies about the specific radiotherapy and chemotherapy regimens, the interval between radiotherapy and chemotherapy before surgery, and whether to reduce the scope of surgery due to pCR, etc., which need to be clarified by more clinical evidence-based medicine.
New results – 5-year survival rate after surgery is significantly improved
With the progress of rectal cancer surgical treatment technology and the promotion of multidisciplinary comprehensive treatment mainly by surgery, the treatment effect of rectal cancer both at home and abroad has been significantly improved. At present, the 5-year survival rate of domestic rectal cancer patients after radical surgery is 60%~67%. Gong Yuan et al. reported that the 5-year survival rate of 272 rectal cancer patients after radical surgery was 62% (92% for stage I patients, 79% for stage II patients, and 41% for stage III patients). Yu Baoming et al [17] reported a 5-year survival rate of 74.2% after surgery in 949 patients with rectal cancer. Scholars from the Cancer Hospital of Sun Yat-sen University retrospectively analyzed the data of 2521 patients with rectal cancer treated by radical resection from 1964 to 2008. The results showed that the 5-year postoperative survival and anus preservation rates of patients in different generations were significantly different, with the 5-year survival and anus preservation rates of 57.2% and 13.9%, respectively, in 1964-1989 (648 cases); 69.6% and 40.1%, respectively, in 1990-1999 (689 cases); and 79.2% and 62.8%, respectively, in 2000-2008 (1184 cases). (P<0.001). Similar reports have been made abroad, and the American Society of Clinical Oncology retrospectively analyzed the 5-year survival rates of all patients with malignancies in 2010 and compared them by three different periods: 1975-1977, 1984-1986, and 1999-2005, in which the 5-year survival rates of patients with rectal cancer were 49%, 57%, and 69%, respectively, a significant improvement [18]. The implementation of TME and preoperative radiotherapy led to a significant increase in the 5- and 7-year survival rates of rectal cancer patients in the southeastern Netherlands, with 49% and 45% in 1980-1989, 55% and 51% in 1990-1994, and 61% and 59% in 1995-2000, respectively.
A review of the history of surgical treatment of rectal cancer shows that rectal cancer has gone from the initial belief of incurability and almost 100% postoperative death, to the first milestone – Miles surgery, and then to the second milestone – TME, which has given patients a better chance of cure, and the local recurrence rate has dropped to 4% -8%. The development of minimally invasive surgery has further improved the quality of life of rectal cancer patients; while the multidisciplinary integrated treatment has better results and the 5-year survival rate of patients has significantly increased; the future surgical techniques, especially minimally invasive techniques and robotic surgery, will also be more perfect.