I. Important updates
1. Detection of RAS gene status, including KRAS exon 2 and non-exon 2 and NRAS, and also BRAF gene status, with or without RAS mutations.
2, FOLFOX+Cetuximab as a treatment option needs to be noted with the following note: data on the treatment of potentially resectable liver metastatic disease remain controversial.
3. For resectable metastatic disease, the total duration of perioperative treatment should not exceed 6 months.
II. Overview
The United States ranks fourth in colorectal cancer diagnoses and second in deaths due to cancer, with data showing a downward trend in incidence and mortality. The improvement in incidence and mortality is determined by cancer prevention, early diagnosis, and better treatment. Clinicians should be clear on the following points when using the guidelines.
1. staging in the guidelines is according to TNM staging.
2. All recommendation levels are 2A unless otherwise noted.
III. Risk assessment
Approximately 20% of colon cancers have familial aggregation, and first-degree relatives of patients with newly diagnosed colorectal adenocarcinoma or adenoma have an increased risk of colorectal cancer. Genetic susceptibility to colorectal cancer includes well-defined genetic syndromes such as Lynch syndrome and familial adenomatous polyp growths. It is recommended that all colon cancer patients should ask for family history and risk assessment.
Lynch syndrome is the most common hereditary colon cancer susceptibility syndrome, accounting for 2-4% of all colorectal cancers. It is caused by mutations in DNA mismatch repair genes (MMR), including MLH1, MSH2, MSH6 and PMS2. Current methods to detect Lynch syndrome include immunohistochemical analysis of MMR protein expression and analysis of microsatellite instability (MSI). If MLH1 protein is absent by immunohistochemistry, BRAF mutations, which can cause MLH1 promoter methylation affecting protein expression, are also tested.
The NCCN supports MMR testing for all patients younger than 70 years of age or older than 70 years of age who meet Bethesda guidelines. In addition, stage II patients should be screened.
2. Other risk factors for colorectal cancer
Other possible risk factors include smoking, red meat and processed meat consumption, alcohol consumption, diabetes, low physical activity, metabolic syndrome, obesity or high BMI. smoking, metabolic syndrome, obesity or red meat and processed meat consumption may be associated with poor prognosis, while a family history of colorectal cancer is associated with a relatively good prognosis, and the data are still debatable.
IV. Staging
The seventh edition of the AJCC staging manual has made some adjustments to the staging of colon cancer. stage II disease is divided into IIA and IIB, and IIC according to whether T3 or T4, and the degree of T4 invasion. n1 and n2 are also further subdivided to reflect the prognostic impact of the number of involved lymph nodes. Tumor deposition in subplasma, mesenteric, non-peritoneal pericolonic or perirectal tissues was defined as N1c. It was subdivided into M1a and M1b according to whether distant metastases were confined to 1 or multiple tissues or organs.
V. Pathology
The pathology report should include the following: cancer grade, penetration depth, extension to adjacent organs, number of regional lymph nodes, number of positive lymph nodes, presence of distant metastasis, distal and proximal margins and circumferential margins, presence of lymphovascular invasion, perineural invasion, and extra-neural tumor deposits. p “and “yp” in TNM staging refer to pathological staging, neoadjuvant treatment and post-operative pathological staging.
1.Margin
The circumferential cut margin (CRM) in rectal cancer is the deepest tumor infiltration and the closest epithelial soft tissue to the tumor, produced by blunt or sharp separation of the posterior peritoneal surface. The transverse colon is a colon entirely surrounded by peritoneum, and the mesenteric resection margin is the CRM. in the 7th edition of AJCC, it is recommended that surgeons should assess the completeness of resection, R0 is complete resection of tumor with negative margin; R1 is incomplete resection of tumor with positive microscopic margin; R2 is incomplete resection with positive sarcoid margin.
2. Lymph nodes
The NCCN committee recommended that at least 12 lymph nodes should be detected, and for T4 damage detecting more lymph nodes would be more reasonable. For the diagnosis of N0, but the number of tested lymph nodes is less than 12 is considered a high risk factor.
3.Extra-nodal tumor deposits
Also known as perineural deposits or satellite nodes, they are scattered deposits of tumor in the adipose tissue surrounding the colorectum of the tumor and are not counted in the total number of lymph nodes involved, and the location of the deposits should belong to the lymphatic drainage area of the primary tumor. Most deposits are thought to be from lymphovascular invasion or perineural invasion. The number of extra nodal deposits should be recorded in the pathology report, which has an impact on DFS and OS.
4. Perineural invasion
Perineural invasion is associated with poor prognosis and is a high risk factor for systemic recurrence.
VI. Role of vitamin D in colorectal cancer
Some studies have shown that vitamin D deficiency may increase the incidence of colorectal cancer and that vitamin D supplementation can reduce the risk of colorectal cancer. There are no studies to test whether vitamin D supplementation improves patient outcomes. Because of the lack of high-level evidence, the committee does not recommend routine testing of vitamin D levels or vitamin D supplementation for patients with colorectal cancer.
VII. Adenocarcinoma of the small intestine and appendix
Because adenocarcinoma of the small intestine and appendix is extremely rare, there are no specific NCCN guidelines. Localized small bowel adenocarcinoma is amenable to surgical resection, but the common and appropriate perioperative treatment for local and distant recurrence is unclear. There are limited data on progressive small bowel adenocarcinoma, and treatment with CapeOX and FOLFOX may be attempted.
Data on appendiceal adenocarcinoma are also scarce, with most patients receiving debulking surgery combined with systemic and intraperitoneal therapy. Some studies have shown that response rates for patients with progressive disease receiving combination chemotherapy are similar to those of patients with progressive colorectal cancer, with regimens containing fluorouracil being the most commonly used. The committee recommends that systemic chemotherapy for adenocarcinoma of the small intestine and appendix be performed with reference to the colon cancer regimen.