I. Overview
The incidence and mortality rate of colorectal cancer in China have been on the rise. 2011 incidence and mortality rate of colorectal cancer were 23.03/100,000 and 11.11/100,000, respectively. Among them, urban areas are much higher than rural areas, and the incidence rate of colon cancer has increased significantly. Most patients are already in the middle and late stages when they are found. In order to further regulate the diagnosis and treatment behavior of colorectal cancer in China, improve the diagnosis and treatment level of colorectal cancer in medical institutions, improve the prognosis of colorectal cancer patients, and guarantee medical quality and medical safety, this specification is formulated.
Diagnostic techniques and applications
(I) Clinical manifestations: Early colorectal cancer may have no obvious symptoms, but the following symptoms may appear when the disease develops to a certain extent.
1. Change in bowel habit.
2. Change in stool characteristics (thinning, bloody stool, mucus stool, etc.).
3, abdominal pain or abdominal discomfort.
4. Abdominal masses.
5.Symptoms related to intestinal obstruction.
6, anemia and systemic symptoms: such as wasting, weakness, low fever, etc.
(II) Disease history and family history.
1. The development of colorectal cancer may be related to the following diseases: ulcerative colitis, colorectal polyposis, colorectal adenoma, Crohn’s disease, schistosomiasis, etc. Patients should be asked about the relevant medical history in detail.
2, the incidence of hereditary colorectal cancer accounts for about 6% of the overall incidence of colorectal cancer, patients should be asked in detail about the relevant family history: hereditary non-polyposis colorectal cancer, familial adenomatous polyposis, dark spot polyp syndrome, juvenile polyposis.
(iii) Physical examination.
1.General condition evaluation, general superficial lymph node condition.
2.Abdominal visual examination and palpation, check the presence of intestinal pattern, intestinal peristaltic waves, abdominal masses.
Rectal finger examination: all suspected colorectal cancer patients must routinely undergo anorectal finger examination. To understand the size, texture, circumference of intestinal wall, basal mobility, distance from the anal verge, infiltration of tumor to the outside of intestine, relationship with surrounding organs, pelvic floor implantation and so on. During finger examination, we must touch carefully to avoid missing diagnosis; touch gently, avoid squeezing, and observe whether the finger stains with blood.
(iv) Laboratory tests.
1.Blood routine: to know whether there is anemia.
2.Urinary routine: Observe whether there is hematuria, combine with urinary imaging to understand whether the tumor invades the urinary system.
3.Fecal routine: pay attention to the presence of red blood cells and pus cells.
4.Fecal occult blood test: It is important for the diagnosis of small amount of bleeding in gastrointestinal tract.
5.Biochemistry and liver function.
6.Patients with colorectal cancer must be tested for CEA and CA19-9 before diagnosis, treatment, evaluation of efficacy and follow-up; patients with liver metastasis are recommended to be tested for AFP; patients with suspected ovarian metastasis are recommended to be tested for CA125.
(v) Endoscopy.
Proctoscopy and sigmoidoscopy are indicated for colorectal lesions with low lesion location.
Colonoscopy is recommended for all patients with suspected colorectal cancer, with the following exceptions.
1, poor general condition and difficult to tolerate.
2.Acute peritonitis, intestinal perforation, extensive adhesions in the abdominal cavity.
3.Perianal or serious intestinal infection.
4.Women during pregnancy and menstruation.
The endoscopy report must include: depth of entry, size of the mass, location from the anal verge, morphology, extent of local infiltration, and pathological biopsy must be performed for suspicious lesions.
Since the colonic intestinal canal may be wrinkled during the examination, the distal distance of the mass from the anal verge seen by endoscopy may be inaccurate. It is recommended to combine CT, MRI or barium enema to clarify the site of the lesion.
(vi) Imaging examinations.
1.Colon barium enema examination, especially air-barium double contrast examination is an important means to diagnose colorectal cancer. However, patients suspected to have intestinal obstruction should be selected with caution.
2.B-type ultrasound: abdominal ultrasound examination can understand whether the patient has recurrence and metastasis, which has the superiority of convenience and speed.
3.CT examination: The function of CT examination is to clarify the depth of lesion invasion into the intestinal wall, the extent of extra-mural spread and the site of distant metastasis.
At present, CT examination of rectal cancer is recommended for the following aspects.
(1) providing the staging of colorectal malignancies.
(2) To detect recurrent tumors.
(3) To evaluate the response of tumors to various treatments.
(4) To elucidate the internal structure and clarify the nature of intrinsic and extrinsic compressive lesions in the intestinal wall found by barium enema or endoscopy.
(5) To evaluate intra-abdominal masses found by barium enema and clarify the origin of the masses and their relationship to surrounding organs.
(6) It can determine the location of the tumor.
4.MRI examination: The indications of MRI examination are the same as CT examination. MRI is recommended as routine examination items for rectal cancer: (1) preoperative staging of rectal cancer; (2) evaluation of liver metastases of colorectal cancer; (3) suspicion of peritoneal and subperitoneal lesions.
5.Transrectal endoluminal ultrasonography: endoluminal ultrasonography or endoscopic ultrasonography is recommended as a routine examination for the diagnosis and staging of middle and low rectal cancer.
6.PET-CT: It is not recommended for routine use, but can be used as an effective adjuvant examination for patients with complex conditions that cannot be clearly diagnosed by routine examination. Preoperative examination suggests stage III or above tumor, and it is recommended for understanding whether there is distant metastasis.
7. Excretory urography: It is not recommended as a routine preoperative examination, and is only applicable to patients with larger tumors that may invade the urinary tract.
(vii) Pathological histological examination.
Pathological biopsy to clarify the nature of occupancy is the basis of colorectal cancer treatment. Cases diagnosed as invasive carcinoma on biopsy are treated with standardized colorectal cancer treatment. If the depth of infiltration cannot be determined by biopsy pathology due to the limitation of biopsy sampling, cases diagnosed as high-grade intraepithelial neoplasia, clinicians are advised to determine the treatment plan by integrating other clinical conditions including the presence or absence of choroidal carcinoma emboli and lymphocytic reaction around the cancer. When recurrent or metastatic colorectal cancer is identified, testing of tumor tissue Ras gene and other related gene status is recommended to guide further treatment.
(viii) Open or laparoscopic exploratory surgery.
Open or laparoscopic exploratory surgery is recommended in the following cases.
1. Colorectal tumor is not clearly diagnosed by various diagnostic means and is highly suspected.
2.Intestinal obstruction and conservative treatment is ineffective.
3.Suspected intestinal perforation.
4.Lower gastrointestinal hemorrhage for which conservative treatment is ineffective.
(ix) Diagnostic steps of colorectal cancer.
For the diagnostic steps of colorectal cancer, please refer to the attached Figure-1. cTNM staging is recommended at the end of diagnosis.
(j) Differential diagnosis of colorectal cancer.
1. Colon cancer is mainly differentiated from the following diseases.
(1) Inflammatory bowel disease. This disease can show symptoms such as diarrhea, mucus stool, pus and blood stool, increased number of stools, abdominal distension, abdominal pain, emaciation, anemia, etc. Those with infection may also have fever and other toxic symptoms, which are similar to the symptoms of colon cancer, and colonoscopy and biopsy are effective methods of differentiation.
(2) Appendicitis. Ileocecal cancer may be misdiagnosed as appendicitis due to local pain and pressure. Especially in advanced stage ileocecal cancer, local necrotic ulceration and infection often occur, and the clinical manifestations include elevated body temperature, increased white blood cell count, local pressure pain or palpable mass, which is often diagnosed as appendiceal abscess and needs to be distinguished.
(3) Intestinal tuberculosis. It is more common in China, and the most common sites are in the terminal ileum, cecum and ascending colon. Common symptoms include abdominal pain, diarrhea and constipation alternately, and some patients may have low fever, anemia, emaciation, weakness and abdominal masses, which are similar to those of colon cancer. However, the systemic symptoms of intestinal tuberculosis patients are more obvious, such as afternoon hypothermia or irregular fever, night sweats, wasting and weakness, which need to be distinguished.
(4) Colon polyps. The main symptom can be blood in the stool, and some patients can also have pus-like stool, similar to colon cancer, and barium enema can show filling defects.
(5) Schistosomiasis granuloma. In a few cases, it may become cancerous. Combining history of schistosome infection, examination of eggs in feces, barium enema and fiberoptic colonoscopy and biopsy can help to identify.
(6) Amoebic granuloma. It may have symptoms of intestinal obstruction or an abdominal mass similar to colon cancer. Amoebic trophozoites and cysts can be found on stool examination, and barium enema examination often reveals a large unilateral defect or circular cut.
(7) Lymphoma. Lymphoma occurs in the terminal ileum, cecum and ascending colon, but also in the descending colon and rectum. Lymphoma is similar to colon cancer in terms of history and clinical manifestations, but bleeding is less common because the mucosa is relatively intact. The differential diagnosis mainly relies on biopsy under colonoscopy to clarify the diagnosis.
2. In addition to differentiating rectal cancer from the above diseases, it is also necessary to differentiate from the following diseases.
(1) Hemorrhoids. Hemorrhoids usually have painless blood in stool, and the blood is bright red and does not mix with the stool, while rectal cancer blood in stool is often accompanied by mucus and mucus stool and rectal irritation symptoms. Patients with blood in stool must be routinely examined by rectal finger.
(2) Anal fistula. Anal fistulas are often caused by perianal abscess due to anal sinusitis. Patients with a history of perianal abscess, localized redness and pain, and rectal cancer have more obvious differences in symptoms and are easier to differentiate.
(3) Amoebic enteritis. The symptoms are abdominal pain and diarrhea, and the lesion involving the rectum may be accompanied by shortness of breath. The stool is dark red or purplish blood and mucus. Enteritis can cause proliferation of granulation and fibrous tissue, thickening of the intestinal wall and narrowing of the intestinal lumen, which can be easily misdiagnosed as rectal cancer, and fiber colonoscopy and biopsy are effective means of differentiation.
(4) Rectal polyps. The main symptom is blood in the stool, colonoscopy and biopsy are effective means of differentiation.
Pathological evaluation
3. Surgical specimens.
(1) Intestinal wall and tumor.
(1) Describe and record the general type of tumor. Cut the tumor specimen along the long axis of the intestinal wall, perpendicular to the intestinal wall, and take the tumor tissue fully, depending on the size, depth of infiltration, different texture and color of the tumor, and at least one full thickness tumor and intestinal wall tissue at the deepest level of tumor infiltration to determine the deepest level of tumor invasion, especially pay attention to the plasma membrane involvement. The tissues that can show the relationship between the tumor and the adjacent mucosa should be excised.
② Excision of distal and proximal surgical margins. It is recommended to excise the tract/pericircular margin. For cases with suspected positive tract/pericircular margin, it is recommended to excise the part marked by the surgeon with ink. It is recommended to mark the different margins separately as much as possible.
③ Record the distance of the tumor from the distal and proximal margins.
④ If the bowel specimen contains the ileocecal region or anal canal or anus, it should be taken from the ileocecal flap, dentate line, anal margin, and also from the appendix; if the tumor involves the above areas, a tissue block that adequately shows the extent of the lesion should be cut.
⑤ For radical resection of low and middle rectal cancer, complete resection of rectal mesentery is required. It is recommended that pathologists should systematically examine the surgical specimens, including the integrity of the mesentery and whether there is tumor invasion at the circumferential cut edge, which is an important index to evaluate the quality of total rectal mesentery resection.
(2) Lymph nodes.
It is recommended that surgeons send lymph nodes in groups according to local anatomical signs and intraoperative views to facilitate the localization of lymph node drainage areas; in the absence of medical advice or markings from surgeons sending lymph nodes in groups, pathologists should detect lymph nodes in specimens according to the following principles: all lymph nodes should be taken (at least 12 lymph nodes are recommended to be detected. Patients who have received preoperative treatment may have fewer than 12 lymph nodes). All lymph nodes that are negative to the naked eye should be sent intact, and those that are positive to the naked eye may be partially excised and sent for examination.
(3) Recommended volume of tissue block to be taken: no larger than 2×1.5×7.5px.
(iv) Pathological types.
1. Early colorectal cancer.
Cancer cells penetrating the colorectal mucosal muscle layer and infiltrating into the submucosa, but not involving the intrinsic muscle layer, regardless of whether there is lymph node metastasis, is called early colorectal cancer (pT1). The lesions with heavy heterogeneous epithelial hyperplasia and the depth of infiltration cannot be judged are called high-grade intraepithelial neoplasia, and if the cancerous tissue infiltrates the lamina propria, it is called intramucosal cancer.
It is recommended to measure and grade the depth of submucosal infiltration of early colorectal cancer, namely SM1 (submucosal infiltration depth ≤1mm) and SM2 (submucosal infiltration depth >1mm).
2.The general types of progressive colorectal cancer.
(1) Augmentation type. Any tumor whose main body protrudes into the intestinal lumen belongs to this type.
(2) Ulcerated type. Any tumor that forms ulcers deep into or through the muscular layer belongs to this type.
(3) Infiltrative type. The tumor infiltrates diffusely into all layers of the intestinal wall, thickening the local intestinal wall, but there is often no obvious ulcer or bulge on the surface.
3.Histological types
(1) Adenocarcinoma.
(2) Mucinous adenocarcinoma.
(3) Indolent cell carcinoma.
(4) squamous carcinoma.
(5) adenosquamous carcinoma.
(6) medullary carcinoma.
(7) Undifferentiated carcinoma.
(8) Other.
(9) Carcinoma, type cannot be determined.
4.Histological grading.
The histological grading criteria of colorectal cancer are shown in Table 1.
(V) Pathology report content.
1. Pathology report contents and requirements for biopsy specimens.
(1) Basic patient information and delivery information.
(2) If there is intraepithelial neoplasia (heterogeneous hyperplasia), report the grading.
(3) In case of invasive carcinoma, distinguish the histological type.
(4) When colorectal cancer is identified, mismatch repair (MMR) protein (MLH1, MSH2, MSH6, PMS2) and Ki-67 expression are recommended.
Clinicians should understand that biopsy pathology cannot fully determine the depth of infiltration due to the limitation of biopsy sampling depth, so the tumor tissue may be high-grade intraepithelial neoplasia or intra-mucosal carcinoma confined to the mucosa.
2. Contents and requirements of pathology report of endoscopically resected adenoma specimens.
(1) Basic information of the patient and information of the sending examination.
(2) Size of the tumor.
(3) Grading of intraepithelial neoplasia (heterogeneous hyperplasia).
(4) In case of infiltrative carcinoma, report the histological staging, grading, depth of infiltration, cutting edge, vascular invasion, and mismatch repair (MMR) protein (MLH1, MSH2, MSH6,PMS2) expression of the cancer tissue.
If pT1, grade 3 and 4 differentiation, vascular invasion, and positive cut margins are present, additional surgery should be performed to expand the resection. In other cases, enteroscopic resection is sufficient, but regular postoperative follow-up is required.
① Histologic features with good prognosis include: grade 1 or 2 differentiation, no vascular or lymphovascular infiltration, and “negative cut margins”.
② Histological features with poor prognosis include: grade 3 or 4 differentiation, vascular and lymphovascular infiltration, and “positive cut margins”.
③ Positive cut margin is defined as: tumor less than 1mm from the cut margin or cancer cells visible in the cut margin of the electric knife.
3. Contents and requirements of pathological report of surgical specimen.
(1) Basic information of the patient and the information of the sending examination.
(2) General conditions: tumor size, general type, depth of infiltration seen by the naked eye, length of both ends of resected intestinal canal from the distal and proximal ends of the tumor.
(3) Degree of tumor differentiation (tumor staging and grading).
(4) Depth of tumor infiltration (T-stage) (T-stage or ypT is based on viable tumor cells; mucus lakes without cells within the specimen after neoadjuvant therapy are not considered as tumor residual).
(5) The number of lymph nodes detected and the number of positive lymph nodes (N stage); and extra-lymph node tumor implantation (ENTD, ExtraNodal Tumor Deposit), which refers to irregular tumor solid nodules deposited in the peri-colorectal adipose tissue away from the primary tumor margin, without histologic evidence of residual lymph nodes but distributed along the lymphatic drainage pathway of the tumor.
(6) The status of the proximal cutaneous margin and distal cutaneous margin.
(7) It is recommended to report the status of the tethered/peri-annular margins (if the tumor is very close to the margins, the distance between the tumor and the margins should be measured and reported under the microscope, and the tumor within 1 mm of the margins should be reported as positive for the margins).
(8) Evaluation of the efficacy of neoadjuvant radiation (or chemotherapy).
(9) Vascular invasion (V for vascular, V1 for microscopic vascular infiltration, V2 for visual vascular infiltration, and L for lymphatic vessels). It is recommended to try to distinguish between vascular and lymphatic infiltrations.
(10) Nerve invasion.
(11) Expression of mismatch repair (MMR) proteins (MLH1, MSH2, MSH6, PMS2). It is recommended to detect the gene status and methylation status of mismatch repair proteins optionally.
(12) Detection of K-ras, N-ras, BRAF gene status is recommended when recurrent or metastatic colorectal cancer is identified. They can be determined from biopsy specimens if surgical resection specimens are not available.
The prerequisite for a complete pathology report is a detailed pathology request form completed by the clinician, describing in detail the surgical findings and relevant clinical ancillary tests and clearly labeling the lymph nodes. Mutual communication, trust and cooperation between clinicians and pathologists are the basis for establishing correct staging and guiding clinical treatment.
IV. Surgical treatment
(a) Standardized surgical treatment of colon cancer.
1. Principles of surgical treatment of colon cancer.
(1) Comprehensive exploration, from far to near. The liver, gastrointestinal tract, uterus and adnexa, pelvic floor peritoneum, and related mesenteric and major vascular lymph nodes and adjacent organs of the tumor must be explored and recorded.
(2) Adequate resection of the intestinal canal, clearing of regional lymph nodes, and whole block resection are recommended. Routine clearance of lymph nodes from two or more stations is recommended.
(3) Recommend sharp separation technique.
(4) Surgical debridement from distant to near is recommended. It is recommended to deal with tumor trophoblastic vessels first.
(5) It is recommended to follow the principle of “no-touch” surgery.
(6) It is recommended to change gloves and irrigate the abdominal cavity after resection of the tumor.
(7) For tumors that have lost the chance of radical surgery, if the patient has no symptoms of bleeding, obstruction, or perforation, there is no need for palliative resection of the primary site first.
2.Surgical treatment of early colon cancer.
(1) T1N0M0 colon cancer: local excision is recommended. If the preoperative endoscopic ultrasonography is T1 or the pathology suggests T1 after local resection, if the resection is complete and has good prognostic histological features (such as good differentiation and no vascular infiltration), then no further surgical resection is recommended, whether broad-based or tipped. If there are histologic features with poor prognosis, or if the resection is not complete and the specimen is fragmented with cut margins that cannot be evaluated, colon resection with regional lymph node dissection is recommended.
(2) Choroidal adenomas with a diameter of more than 62.5 px have a high rate of carcinoma and colon resection with regional lymph node dissection is recommended.
Note: Local resection specimens must be spread and fixed by the surgeon, marked with orientation and sent for pathological examination.
3.T2-4, N0-2, M0 colon cancer.
(1) The preferred surgical procedure is resection of the corresponding colon plus regional lymph node dissection. Regional lymph node dissection must include the paramedian, intermediate and mesenteric root lymph nodes. It is recommended to label the lymph nodes in the root of the mesentery and send them for pathological examination; complete resection is recommended if metastases are suspected in lymph nodes outside the area of clearance, and those that cannot be resected are considered as palliative resection.
(2) A more extensive colectomy is recommended for patients with a family history of hereditary nonpolyposis colorectal cancer (HNPCC), or a significant family history of colon cancer, or simultaneous multiple primary colon cancer.
(3) Tumor invasion of surrounding tissues and organs is recommended to combine with whole organ resection.
(4) Clinical diagnosis of neoplastic colon is highly suspicious of malignancy, and for some reasons pathological diagnosis cannot be obtained, if the patient can tolerate surgery, surgical exploration is recommended.
(5) The following conditions are recommended for performing laparoscopic-assisted colectomy.
(i) The procedure is performed by a surgeon with laparoscopic experience.
(ii) No abdominal adhesions that would seriously interfere with the procedure.
(3) No manifestation of acute bowel obstruction or perforation.
(6) For resectable colon cancer that has caused obstruction, stage I resection anastomosis, or stage I tumor resection with distal closure of proximal stoma, or stage II resection after fistula, or stage II resection after stent implantation is recommended. If the tumor is locally advanced and cannot be resected or clinically intolerant to surgery, it is recommended to give palliative treatment.
4. Principles of surgical treatment of liver metastasis.
See the specification for treatment of liver metastasis from colorectal cancer.
5.Principles of surgical treatment of lung metastasis.
(1) The primary foci must be radically resectable (R0).
(2) The presence of extrapulmonary resectable lesions does not prevent resection of pulmonary metastases.
(3) Complete resection must take into account the extent and anatomic location of the tumor, and adequate function must be maintained after lung resection.
(4) Staged resection may be considered in some patients.
(5) Chemotherapy (preoperative chemotherapy and/or postoperative adjuvant chemotherapy) should be considered regardless of whether the lung metastases can be resected.
(6) Lesions that are not surgically resectable may be treated with ablation (if complete ablation of the lesion is possible).
(7) If necessary, surgical combined ablation treatment.
(8) Extrapulmonary resectable metastatic lesions can be treated concurrently or in stages.
(9) Extra-pulmonary resection of metastatic lesions is not recommended in the presence of unresectable lesions.
(10) Comprehensive treatment after multidisciplinary discussion is recommended.
(II) Surgical treatment of rectal cancer.
The principles of laparoscopic treatment for rectal cancer surgery are the same as those for colon cancer.
1. Local excision of rectal cancer (T1N0M0).
The treatment and handling principles of early rectal cancer (T1N0M0) are the same as those of early colon cancer. Early rectal cancer (T1N0M0) must meet the following requirements if resected through the anus.
(1) Tumor size <75px.
(2) Cutting edge >3mm from the tumor.
(3) Mobile, not fixed.
(4) Within 200 px of the anal verge.
(5) Applicable to T1 tumor only.
(6) Endoscopically resected polyps with cancerous infiltration, or indeterminate pathology.
(7) Without vascular lymphovascular infiltration (LVI) or nerve infiltration (PNI).
(8) High – intermediate differentiation.
(9) No evidence of lymph node enlargement on pretreatment imaging.
Note: Local resection specimens must be spread and fixed by the surgeon, marked with orientation and sent for pathological examination.
2. Rectal cancer (T2-4,N0-2,M0).
Radical surgery must be performed. The upper and middle rectal cancer is recommended to perform low anterior resection; low rectal cancer is recommended to perform combined abdominoperineal resection or cautiously choose anal preservation surgery. The principle of total mesenteric resection for rectal cancer must be followed for middle and lower rectal cancer, and the rectal mesentery should be freed as sharply as possible, together with the distal mesentery of the tumor, and the whole block should be resected to ensure the negative circumferential margin as much as possible, and follow-up treatment should be added for those with suspected positive circumferential margin. The distal resection margin of the intestinal wall should be ≥50px from the tumor, and the distal resection margin of the rectal mesentery should be ≥125px from the tumor or the whole rectal mesentery should be resected. The anal sphincter function, urination and sexual function should be preserved as much as possible under the premise of radical treatment of tumor. The treatment principles are as follows.
(1) Remove the primary tumor and ensure sufficient incisional margin, with the distal margin at least 50 px from the distal end of the tumor. for lower rectal cancer (less than 125 px from the anus) with distal incisional margin 1 to 50 px from the tumor, intraoperative frozen pathological examination is recommended to confirm negative incisional margin.
(2) Remove the lymphatic fatty tissue in the drainage area.
(3) Preserve the pelvic autonomic nerve as much as possible.
(4) Surgery is recommended at an interval of 6-12 weeks after neoadjuvant (preoperative) radiotherapy.
(5) Combined organ resection is recommended for tumors invading surrounding tissues and organs.
(6) For patients with neoplastic rectum in combination with intestinal obstruction, with high clinical suspicion of malignancy without pathological diagnosis, not involving anal preservation and tolerating surgery, dissection is recommended.
(7) For resectable rectal cancer that has caused intestinal obstruction, stage I resection anastomosis, or Hartmann’s procedure, or stage II resection after fistula, or stage II resection after stenting to relieve obstruction is recommended. Intraoperative bowel irrigation is recommended prior to stage I resection anastomosis. If the risk of anastomotic fistula is estimated to be high, Hartmann procedure or stage I resection anastomosis and prophylactic enterostomy are recommended.
(8) If the tumor is locally advanced and unresectable or clinically intolerant to surgery, palliative treatment is recommended, including the option of radiation therapy to manage uncontrollable bleeding and pain, stenting to manage bowel obstruction, and supportive therapy.
(9) If there is clear tumor residue intraoperatively, it is recommended to place silver clips as markers for subsequent radiotherapy.
3. Liver and lung metastasis of rectal cancer.
The treatment principles for liver and lung metastases of rectal cancer are the same as those for colon cancer.