1. More definite localization and diagnosis.
The 2007 NCCN guidelines clearly defined rectal cancer for the first time as “cancerous lesions within 12 cm from the anal verge (rather than the dentate line) under proctoscopy”, which is equivalent to the traditional definition of “low to intermediate rectal cancer”. The basis of the above definition is that there is a significant difference in the principles of surgical resection, comprehensive treatment strategy and local recurrence rate between tumors within 12 cm and those above 12 cm.
This means that “high-grade rectal cancer” above 12 cm from the anal verge will be classified as colon cancer, and its preoperative neoadjuvant radiotherapy and postoperative adjuvant radiotherapy are not recommended by the guidelines. In view of the importance of clinical value of localization, the 2009 NCCN guidelines emphasized for the first time the use of “rigid proctoscopy” instead of “proctoscopy” as one of the necessary preoperative evaluation methods.
2. Comprehensive update of staging and diagnosis.
Regardless of imaging or pathological staging, the NCCN guidelines recommend the use of the TNM staging system developed by the AJCC, and the 7th edition has been in use since 2010. Standardized specimen handling and histological examination can provide accurate pathological TNM staging (pTNM), which has become the “gold standard” for tumor staging and is used to assess prognosis and select adjuvant treatment strategies.
Similarly, accurate clinical TNM staging (cTNM) obtained through baseline examination is relevant to the choice of initial treatment (surgery or preoperative chemoradiotherapy). NCCN guidelines recommend endorectal ultrasound, rectal or pelvic MRI, and CT of the chest, abdomen and pelvis as preoperative staging tools.
Meanwhile, MRI can also accurately display the soft tissue structures of the rectal mesentery, making it the best choice for preoperative assessment of the circumferential margins of progressive rectal cancer. The NCCN guidelines do not recommend PET-CT as a routine preoperative examination and recurrence monitoring evaluation for rectal cancer.
Rules of surgical specification
1. Transanal surgical adaptation proves to be confirmed.
In 2009, the NCCN guidelines set the tumor staging indications for transanal surgery for rectal cancer as T1T2N0M0, and in 2010, it was strictly limited to T1N0M0. For tumors with proven indications and adequate exposure in the rectum, the recommended procedure is gradually minimally invasive, and from 2007 to 2010, “transanal minimally invasive surgery can be considered. From 2007 to 2010, “transanal minimally invasive surgery can be considered” was changed to “transanal endoscopic microsurgery (TEM) can be considered” in 2011. Between the selection of indications and minimally invasive surgery, it should be avoided that contraindicated cases are “minimally invasive”.
2. TME has become the standard.
In the past 5 years, the NCCN guidelines for rectal cancer have always recommended that combined transabdominal perineal resection or low anterior resection should follow the principle of TME, thus reducing the positive rate of circumferential margins. Regarding the extent of distal tumor resection (including rectal mesentery and intestinal canal), the 2005 NCCN guidelines recommended that the surgical extent should be 4-5 cm to the lower edge of the tumor to achieve adequate resection of the rectal mesentery.
The 2006 guidelines added that for low rectal cancer less than 5 cm from the anal verge, resection of 1 to 2 cm of the distal intestinal canal is acceptable, but intraoperative frozen pathological examination is required to confirm negative margins. Regarding the scope of lymph node dissection, the guidelines recommend removing or biopsying the clinically suspicious metastatic lymph nodes outside the scope of lymph node dissection as much as possible.
3, laparoscopic surgery is still recommended for clinical studies.
In 2005, the American Association of Colorectal Surgeons and the Society of Gastrointestinal Endoscopic Surgeons issued a joint statement: for curable colon cancer, laparoscopic colectomy performed by experienced surgeons can achieve the same tumor-related survival rate as open surgery. 2006 NCCN guidelines for colon cancer issued a recommendation that “laparoscopic surgery can be used for curable colon cancer. treatment of curable colon cancer”.
However, due to the lack of evidence, the NCCN rectal cancer guidelines recommended laparoscopic surgery for rectal cancer “only in clinical trials”, and to date, the recommendations for laparoscopic surgery for rectal cancer remain unchanged in the 2012 guidelines because the results of comparative studies on the long-term outcomes of laparoscopic and open rectal cancer surgery are not yet available.
4. The status of surgery for metastatic rectal cancer is becoming more prominent.
”The NCCN guidelines for surgical treatment strategy for CLM from 2007 to 2011 are summarized as follows.
(1) Liver resection is the 1 treatment for resectable CLM.
(2) R0 resection should be performed according to the extent of the lesion distribution as well as its anatomical location, provided that adequate liver function is preserved.
(3) The primary tumor must be capable of radical resection without unresectable extrahepatic metastases, and non-R0 resection for tumor reduction is not recommended.
(4) Both primary and metastatic tumors should be radically resected and can be operated on concurrently or by staging.
(5) If the residual liver volume is insufficient, preoperative portal vein embolization or staged hepatectomy can be considered.
(6) Surgical resection can be combined with ablation techniques, provided that all metastases can be removed or ablated.
(7) Re-excision may be considered in certain patients.
(8) The resectability of initially unresectable or potentially resectable lesions should be re-evaluated after neoadjuvant therapy.
Gradual improvement of neoadjuvant treatment options
The 2007 NCCN guidelines first recommended neoadjuvant therapy before TME surgery, but did not specify whether neoadjuvant radiotherapy, neoadjuvant chemotherapy or neoadjuvant radiotherapy was needed; the 2008 guidelines clearly proposed the choice of simultaneous preoperative neoadjuvant radiotherapy for TNM stage II (T ≥ 3) and stage III (N ≥ 1) cases, and recommended the use of fluorouracil-based chemotherapy in combination with radiotherapy at the same time, unless Patients with complications such as bleeding or obstruction or contraindications to neoadjuvant therapy should not be treated with surgery.
The selection of indications for neoadjuvant therapy and the evaluation of its efficacy should be based on medical imaging + pathological examination. Misjudgment of TNM staging (yTNM) after neoadjuvant therapy can lead to wrong decision of adjuvant therapy. Therefore, it is once again emphasized that “diagnosis priority and standardized diagnostic methods” should be applied throughout clinical practice.
Targeted therapy is gradually recognized
The current guidelines recommend the following targeted therapies for rectal cancer: bevacizumab (2005) for vascular endothelial growth factor (VEGF); cetuximab (murine origin, 2006) and panitumumab (human origin, 2007) for epidermal growth factor receptor (EGFR). 2007).
The current indications for targeted drug therapy are recommended only for palliative and preoperative neoadjuvant therapy in stage IV cases, but not for postoperative adjuvant therapy; and the choice of cytotoxic chemotherapeutic agents in combination with targeted drugs, or anti-EGFR targeted drugs alone (for selected patients) is recommended. The combination of cytotoxic chemotherapeutic agents, anti-EGFR-targeted drugs and anti-VEGF-targeted drugs is not recommended.
The 2009 guideline added KRAS gene testing and recommended testing for KRAS gene status in patients with advanced rectal cancer, and the use of anti-EGFR-targeted drugs was strictly limited to patients with wild-type KRAS gene status. 2010 guideline recommended further testing for BRAF gene (V600E) mutation in patients with wild-type KRAS gene, mainly because patients with this mutation The prognosis seems to be worse. However, there is no recommendation to date to prohibit the use of anti-EGFR-targeting drugs in patients with wild-type KRAS and mutated BRAF genes.