I. Overview
In recent years, with the continuous improvement of people’s living standard, changes in dietary habits and diet structure as well as the aging of the population, the incidence and mortality rate of colorectal cancer in China have maintained an increasing trend. Among them, the incidence rate of colon cancer has increased especially 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
(A) Clinical performance.
Early colorectal cancer may have no obvious symptoms, and the following symptoms may appear only when the disease has developed 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.Intestinal obstruction.
6, anemia and systemic symptoms: such as wasting, weakness, low fever.
(B) Physical examination.
1.General condition evaluation, general superficial lymph node condition.
2.Abdominal visual examination and palpation, check for intestinal pattern, intestinal peristaltic waves, abdominal masses.
3.rectal finger examination: all suspected colorectal cancer patients must routinely undergo anorectal finger examination. To understand the size, texture, circumference of the intestinal wall, basal mobility, distance from the anal verge, infiltration of the tumor to the outside of the intestine, and the relationship with the surrounding organs. During finger examination, we must touch carefully to avoid missing diagnosis; touch gently, avoid squeezing, and observe whether the finger stains with blood.
(C) laboratory tests.
1.Blood routine: to know whether there is anemia.
2.Urinary routine: observe whether there is hematuria, combine with urological imaging to understand whether the tumor invades the urinary system.
3.Fecal routine: the presence of red blood cells and pus cells should be noted.
4.Fecal occult blood test: it has important value for the diagnosis of small amount of gastrointestinal bleeding.
(iv) Endoscopic examination.
Proctoscopy and sigmoidoscopy are suitable for colorectal lesions with low lesion location.
Fiberoptic colonoscopy or e-colonoscopy is recommended for all patients with suspected colorectal cancer, with the following exceptions.
1, poor general condition, difficult to tolerate;
2.Acute peritonitis, intestinal perforation, extensive intra-abdominal adhesions and complete intestinal obstruction;
3, perianal or serious intestinal infection, radiation enteritis;
4, women during pregnancy and menstruation.
Before the endoscopy, you must be prepared for the examination before the liquid diet, laxatives, or clean bowel cleansing, so that the intestinal cavity fecal excretion.
The endoscopy report must include: depth of entry, size of the mass, location from the anal verge, morphology, and the extent of local infiltration, and pathological biopsy of suspicious lesions during colonoscopy.
Since the colon canal may be crinkled during examination, there may be errors in the distance from the anus of the mass seen by endoscopy, and it is recommended to combine CT or barium enema to clarify the site of the lesion.
(E) Imaging examination.
1.Colon barium enema examination, especially air-barium double imaging 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: ultrasound examination can understand whether the patient has recurrence and metastasis, and has the superiority of convenience and speed.
3.CT examination: The role 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 colorectal lesions is recommended for the following aspects.
(1) To provide 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 the intra-abdominal masses found by barium examination and clarify the origin of the masses and their relationship with the surrounding organs.
4.MRI examination: The indications for MRI examination are the same as those for CT examination. MRI examination is recommended for the following cases.
(1) Preoperative staging of rectal cancer;
(2) Evaluation of liver metastases from colorectal cancer;
(3) Suspected peritoneal and subhepatic lesions.
5.Transrectal endoluminal ultrasound: endoluminal ultrasound or endoscopic ultrasound is recommended as a routine examination for the diagnosis and staging of low and middle rectal cancer.
6.PET-CT: It is not recommended for routine use, but it can be used as an effective auxiliary examination for metastatic recurrent lesions that cannot be clarified by routine examination.
7.Excretory urography: not recommended as routine examination before operation, only for patients with large tumor that may invade the urinary tract.
(F) Serum tumor markers.
Colorectal cancer patients must be tested for CEA and CA19-9 before diagnosis, treatment, evaluation of efficacy and follow-up; CA242 and CA72-4 are recommended; AFP is recommended for patients with liver metastases; CA125 is recommended for patients with ovarian metastases.
(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 undergo 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. When recurrent or metastatic colorectal cancer is determined, the K-ras gene status of tumor tissue is detected.
(H) Open abdominal exploration.
In the following cases, open abdominal exploration is recommended.
1.After various diagnostic means, the diagnosis is not clear and colorectal tumor is highly suspected.
2.Intestinal obstruction occurs and conservative treatment is ineffective.
3.Suspected intestinal perforation.
4.Gastrointestinal hemorrhage which is ineffective by conservative treatment.
(ix) Diagnostic steps of colorectal cancer. See the attached figure-1 for the diagnostic steps of colorectal cancer.
(J) Differential diagnosis of colorectal cancer.
1. Colon cancer should be differentiated mainly from the following diseases.
(1) Ulcerative colitis. 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 those of colon cancer, and fiber 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 common sites are in the terminal ileum, cecum and ascending colon. Common symptoms include abdominal pain, abdominal lumps, 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, patients with intestinal tuberculosis have more obvious systemic symptoms, such as afternoon low-grade fever 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, barium enema examination can be shown as filling defects, fiber colonoscopy and biopsy is an effective method of differentiation.
(5) Schistosomal granuloma. Most often seen in endemic areas, but now rare. A few cases can be cancerous. Combined with history of schistosome infection, examination of eggs in stool, as well as barium enema and fiberoptic colonoscopy and biopsy, it can be differentiated from colon cancer.
(6) Amoebic granuloma. There may be symptoms of intestinal obstruction or abdominal masses similar to colon cancer. Amoebic trophozoites and cysts can be found in the stool examination of patients with this disease, and barium enema examination often reveals huge unilateral defects or circular cuts.
2, rectal cancer should be differentiated from the following diseases.
(1) Hemorrhoids. It is not difficult to distinguish hemorrhoids from rectal cancer, and misdiagnosis is often due to lack of careful examination. Hemorrhoids are usually painless blood in stool, and the blood is bright red and does not mix with stool, while rectal cancer blood in stool is often accompanied by mucus and appears as mucus blood stool and rectal irritation symptoms. Patients with blood in stool must routinely perform rectal examination.
(2) Anal fistula. Anal fistulas are often caused by paranal abscess due to anal sinusitis. Patients with a history of paranal 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 the proliferation of granulation and fibrous tissue, thickening the intestinal wall and narrowing 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, fiberoptic colonoscopy and biopsy are effective means of differentiation.
Pathological evaluation
(a) Specimen fixation standards.
1.Fixation solution: 10-13% neutral formalin fixative is recommended, avoid using fixative containing heavy metals.
2, the amount of fixative: must be ≥ 10 times the volume of the fixed specimen.
3, fixation temperature: normal room temperature.
4, fixation time: endoscopic resection of adenoma or biopsy specimens: ≥ 6 hours, ≤ 48 hours. Surgical specimens: ≥ 12 hours, ≤ 48 hours.
(B) sampling requirements.
1, biopsy specimens.
(1) Check the number of clinical specimens sent for examination, and all biopsy specimens sent for examination must be taken.
(2) Each wax block includes no more than 5 biopsy specimens.
(3) Wrap the specimen in gauze or soft permeable paper to avoid loss.
2, endoscopic resection of adenoma specimens.
(1) The specimen should be fixed by the surgeon and marked for orientation.
(2) Record the size of the tumor and the distance of each orientation from the cutting edge.
(3) The specimen is cut perpendicular to the intestinal wall, at an interval of 0 or 3 cm in parallel, and divided into tissue blocks of appropriate size, all of which are recommended to be taken in the same embedding direction. Record the orientation corresponding to the tissue block.
3.Surgical specimens.
(1) Intestinal wall and tumor.
Tumor specimens should be cut along the long axis of the intestinal wall and perpendicular to the intestinal wall, and tumor tissues should be taken fully, depending on the size, depth of infiltration, different texture and color of the tumor, and so on (4 blocks routinely). The tissues that can show the relationship between the tumor and the adjacent mucosa were excised (routinely 2 pieces).
②Cut the distal and proximal surgical margins. The circumferential incision margin is cut according to the part marked by the surgeon.
③Record the distance of the tumor from the distal and proximal surgical margins.
④If the bowel specimen contains the ileocecal part or anal canal or anus, it should be taken at the ileocecal flap, dentate line, anal margin (routinely 1 block each) and appendix (routinely 3 blocks: 2 blocks at the circumferential + 1 block at the blind end); if the tumor involves the above parts, a tissue block that fully shows the extent of the lesion should be excised.
(5) Complete resection of rectal mesentery is required for radical surgery of low and middle rectal cancer, so pathologists need to systematically examine the surgical specimens, including the integrity of mesentery and whether there is tumor invasion at the circumferential cut edge, which is an important index to evaluate the effect 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, which is conducive to 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 lymph nodes 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, 5×0, 3 cm.
(C) the principles of specimen processing and retention time frame after sampling.
1, the preservation of the remaining specimens. Take the remaining tissue preserved in the standard fixative, and always maintain adequate amount of fixative and formaldehyde concentration to avoid specimen drying or tissue decay due to insufficient amount of fixative or concentration reduction; to be ready to supplement the sampling according to the microscopic observation and diagnostic needs; to be ready to review the bulk specimen or supplemental sampling when clinical feedback is received after the issuance of the pathological diagnostic report.
2. The time limit for processing the remaining specimens. It is recommended that after 1 month of the issuance of the diagnostic pathology report, no clinical feedback is received, and no review is requested due to differences in opinion from outside the hospital, the hospital can handle the situation itself.