Overview
Colon and rectal cancer in the United States, Canada and Western Europe and other countries are among the common diseases, in Eastern and Southern Europe its incidence rate is moderate, while Africa, Asia and some Latin American regions for low incidence. In reality, both colon and rectum are large intestine, which are inseparable. In developed countries with a high prevalence of the disease, there have been no noteworthy changes in morbidity or mortality over the past 20 years. In countries with moderate or low risk, colorectal cancer, on the other hand, shows an increase. Several new advances have been made in recent years in the diagnosis, treatment and prevention of colorectal cancer.
Epidemiological and etiological studies have further elucidated the relationship between diet and colorectal cancer, and it is possible to prevent colorectal cancer by improving lifestyles. A more reasonable staging scheme has been proposed in pathology, and the importance of rectal finger diagnosis for rectal cancer diagnosis has been emphasized in diagnosis. Fiberoptic colonoscopy is a feasible method for early detection of patients. In recent decades, the development of various biological techniques has made people realize the importance of selecting treatment plans according to the biological characteristics of tumors.
However, the status of surgery in the treatment of anorectal tumors has never been lowered. Surgical treatment emphasizes the whole resection of tumors and regional lymph nodes, and improves surgical methods to preserve the anus and reconstruct the anus as much as possible to improve the quality of life under the premise of improving the cure rate. At the same time, the comprehensive treatment of radiotherapy, chemotherapy and immunotherapy has been carried out. Preoperative radiotherapy can shorten the disease period, improve the surgical resection rate and reduce the distant metastasis rate, and postoperative radiotherapy can reduce the recurrence rate. Chemotherapy is still chosen from 5-fluorouracil drugs.
Diagnosis】
The diagnosis can be made based on the above clinical manifestations and the following tests.
(a) Laboratory examination Routine blood examination can understand whether there is anemia, routine stool examination can pay attention to the presence of red blood cells and pus cells, the stool occult blood test of colon cancer is mostly positive, this method is simple and easy to use and can be used as the initial screening method of colon cancer census and routine examination of colon disease, for those with positive stool occult blood test, barium enema, x-ray examination and endoscopy should be done further. If the fecal occult blood test is negative, but the clinical suspicion of colorectal cancer is high, the examination should be repeated or barium enema should be done.
(X-ray examination is one of the important methods to diagnose colon cancer. Barium enema examination can observe intestinal peristalsis, morphology of colon pouch, whether there is narrowing or dilatation of intestinal cavity, and whether there is mass in intestinal cavity, etc. In the diagnosis of rectal cancer, double contrast imaging with gas-barium enema helps to understand and exclude multiple primary cancers. However, it is useless for diagnosing rectal cancer and may even give a false impression, especially for early or smaller lesions. Because when performing enema, the insertion of the anal canal has often passed through or beyond the lesion, the lesion cannot be shown in x-ray, and one arrives at the diagnosis of no lesion from then on.
(C) fiberoptic colonoscopy
1, the indications for fiberoptic colonoscopy
(1) Unexplained blood in stool and persistent positive blood in stool bath, suspected of colon tumor.
(2) Suspected colon polyps or polyps found by x-ray examination need to distinguish benign and malignant.
(3) Those who need to determine the scope of colon cancer lesions before surgery.
(4) To check whether there is recurrence of colon cancer after surgery.
2.Contraindications of fiberoptic colonoscopy
(1)Any serious acute colitis.
(2)Those who are suspected of intestinal perforation or acute peritonitis.
(3) Severe cardiopulmonary insufficiency and those with significant intestinal adhesions found after previous abdominal and pelvic surgery.
Through fiberoptic colonoscopy, we can not only see the existence of cancer, but also observe its size, location, the scope of local infiltration and whether the intestinal wall and surrounding tissues have adhesions, so as to determine the early and late stage of the disease and the degree of lesions. The good depth of colonoscopy is of great value to the microscopic lesions that are not easily detected by barium enema.
(iv) Rectal examination About 80% of rectal cancer can be detected during rectal examination, and about 80% of cases with delayed diagnosis of rectum are due to failure to do rectal examination.
(V) CT diagnosis When the tumor grows outside the intestinal wall and expands to the adjacent structures, so that the outer contour of the intestinal wall is blurred, CT can help to make the diagnosis;
1. CT manifestations of colon tumor are.
① Intraluminal mass, which can be smooth and sharp or with villi-like edges;
②Limited or circumferential thickening of the intestinal wall, most of the lesions are larger than 2cm in diameter;
③The CT value of the lesion area is about 40-60Hu;
④Diffuse calcification or central hypodensity area due to necrosis may occur;
⑤ Mucinous adenocarcinoma lesions have low density and can be seen as watery density areas;
(6) The intestinal wall appears blurred when the tumor penetrates the intestinal wall to reach the plasma membrane layer and extends outward;
(7) Direct invasion of surrounding organs, such as stomach, pancreas, gallbladder and rectum;
(8) Local and retroperitoneal lymph nodes are enlarged.
2.CT manifestations of rectal cancer.
① Substantial masses in the intestinal cavity, varying in size, often between l to 10 cm, with irregular margins and may be lobulated. The density of the mass is related to the size, and the density of those less than 5cm is more uniform, while those larger than 5cm may have necrosis within the tumor and the density is not uniform. ②Limited or circumferential thickening of intestinal wall. Early rectal cancer intestinal wall thickening is not obvious and is often limited, but intestinal wall thickness is often greater than 6 cm.
③Circular or asymmetric narrowing of the intestinal cavity with irregular morphology and varying degrees of stenosis, and in severe cases the intestinal cavity is occluded.
When the tumor crosses the muscle layer to reach the plasma membrane layer and the surrounding fat layer, it shows blurring of the plasma membrane surface, increasing density of the peri-intestinal fat layer, and sometimes the soft tissue shadow in the form of cords can be seen, which is generally considered as a direct sign of peri-intestinal infiltration, but it is not specific for inflammatory lesions.
⑤ Invasion of adjacent tissues and organs, such as perirectal muscles, prostate, vagina, ureter, pelvis, etc.
⑥Lymph node enlargement signs.
Liver metastasis is less common in rectal cancer than colon cancer, and the metastases are mostly small and multiple, and isolated metastases are rare.
(8) Cancer perforation.
(vi) Serum carcinoembryonic antigen (CEA) examination CEA examination does not have specific diagnostic value and has certain false positives and false negatives, so it is not suitable for screening or early diagnosis, but it is helpful for estimating prognosis and observing the effect of treatment and recurrence.
(VII) Ultrasonography Endorectal ultrasonography is a new diagnostic method aiming at detecting the invasion of rectal cancer and the degree of tumor infiltration to rectal wall.
Treatment measures
I. Surgical treatment of colon cancer
Principles of surgical treatment.
① Excision of all malignant tissues.
② Remove all or most of the cancerous organs.
③ Eliminate the main way of lymphatic spread.
④In order to prevent tumor cells from forming embolus when touching the membrane tumor during surgery, the venous blood flow should be controlled early.
II. Surgical treatment of rectal cancer
The principle of radical treatment of rectal cancer The principle of radical treatment is to remove the rectum and the blood vessels above the rectum, together with the perirectal tissues and the lymphatic drainage area with the possibility of metastasis. The methods of radical treatment are divided into two categories, one is to completely remove the rectal canal and then perform artificial anus; the other is to partially remove the rectum to preserve the anal sphincter, and the factors for choosing surgery include the following.
The middle third, i.e. the lower margin of the tumor is between 6 and 10 cm from the anal margin, is more controversial for the choice of operation.
2.Pathological types: in situ cancer can be resected 1cm rectum from the lower edge of cancer; ulcerated type, cauliflower type and annular cancer can be resected 4~5cm from the lower edge of
rectum; infiltrating type cancer should be resected more than 7cm rectum at the lower edge.
3. Gender, body type and age: women have wide pelvis, so it is easier to separate and resect anastomosis, and it is appropriate to preserve anus as much as possible; men have narrow pelvis, so it is difficult to anastomosis, and it is prudent to preserve anus; thin and tall patients are suitable for anus-preserving surgery, while short and fat patients are not suitable; young people are prone to early metastasis of rectal cancer, and the malignancy is generally higher. Try to choose Mayer’s surgery. Patients over 60 years old should choose palliative treatment due to poor general condition.
4.Degree of differentiation and fixation: low differentiated cancer has high local recurrence rate and requires more resection of edges and complete lymph node dissection, while medium and high differentiated cancer has relatively good malignancy and can have less resection of tumor edges; if cancer is fixed with surrounding tissues and organs, it should be resected together and then reconstructed or rerouted according to resected organs.
5. Radical surgery is not suitable for advanced rectal cancer with distant metastasis, and palliative resection or upper segment fistula should be considered to relieve obstruction.
Radiation therapy for colorectal cancer
Although surgical resection is the main means of colorectal cancer treatment, however, the local recurrence rate after surgery alone is high because most of the patients are not in the early stage when they are operated, and the local recurrence rate after Dukes’ B stage is about 25%-30%, and the local recurrence rate after Dukes’ C stage is about 50%. Therefore, tumor invasion into soft tissues around the rectum cannot be completely removed by surgery.
Therefore, pelvic radiotherapy is the only available and effective method to remove these cancer deposits. However, patients with colon cancer have no significant effect on preoperative and postoperative radiotherapy. Radiation therapy is only applicable to intraoperative radiotherapy for colon cancer patients.
(A) Radiotherapy program for colon cancer
1.Radical radiotherapy: complete killing of tumor cells by radiotherapy is only applicable to a few early stage patients and patients with special sensitive cell types.
2.Symptomatic radiotherapy: It aims to reduce symptoms. It is suitable for palliative treatment such as pain relief, hemostasis, secretion reduction, tumor shrinkage and tumor control.
3.Integrated treatment of radiotherapy and surgery, planned and integrated application of both surgery and radiotherapy.
(B) Modes of radiotherapy for colorectal cancer
1.Pre-operative radiotherapy: pre-operative radiotherapy has the following advantages.
①The activity of cancer cells is weakened, so that the cancer cells disseminated or remaining at the time of surgery are not easily survived.
(2) For huge and fixed cancer tumors which are estimated to be difficult to resect, preoperative radiotherapy can reduce the size of the tumor and thus increase the resection rate.
③Research on radiobiology shows that when blood supply or oxygen supply is reduced, preoperative cancer cells are more sensitive to radiation than postoperative ones.
The dose of preoperative radiotherapy should be strictly controlled, and a medium dose (3500~4500cGY) is appropriate, which not only does not increase the complications of surgery, but also can improve the efficacy of surgery.
2, postoperative radiotherapy: postoperative radiotherapy has the following advantages.
①According to the surgical findings, after the primary tumor is removed, the site of possible residual tumor is marked and localized, so that the irradiation site may be more precise, and the irradiation is selective and has better effect.
②After the primary tumor is removed, the tumor load is significantly reduced, which is conducive to improving the effect of residual cancer on radiation.
3.Intraoperative radiotherapy: intraoperative high-dose irradiation with β-ray for suspected residual cancer sites and sites that cannot be completely removed.
(C) Contraindications of radiotherapy for colorectal cancer
1.Severe wasting and anemia.
2.Severe cardiac and renal insufficiency that cannot be relieved by treatment.
3.Severe infection or sepsis.
4.Patients who can no longer tolerate local radiotherapy again.
5.The cell count is lower than 3×109/L, platelet is lower than 80×109/L and hemoglobin is lower than 80g/L, radiotherapy is generally suspended.
(IV) Complications of radiotherapy
1.The healing of perineal incision is slightly delayed in patients undergoing preoperative radiotherapy.
2.Abdominal pain, nausea, vomiting, diarrhea and other symptoms.
3.Simple anusitis (1%-2%), local perineal scarring, poor healing or sclerosis with pain (2%), incomplete obstruction of small intestine (1%).
4. urinary incontinence (0.5% to 1%), small bladder disease and hematuria (1.5%), etc.
5., whole blood cytopenia.
(E) Adjuvant therapy of radiotherapy
1. For those who have nausea and vomiting, they should be treated with drugs such as gastrofacial, and those who have recalcitrant vomiting should be treated with cardiofacial.
2.For those with decreasing white blood cell count, give drugs to raise white blood cell. For example, vitamin B4, blood, leucovorin, leucovorin, etc.
3.For skin reactions, apply talcum powder on the perineum for first degree reaction, and apply gentian violet liquid or skin relaxation ointment for second degree reaction.
IV. Chemotherapy for colorectal cancer
Chemotherapy is one of the important adjuvant treatments for colorectal cancer and an indispensable part of the comprehensive treatment of colorectal cancer.
chemotherapy is one of the important adjuvant treatments for colorectal cancer and an important part of the comprehensive treatment of colorectal cancer. The purpose of treatment is to prevent and reduce recurrence and metastasis, so as to improve the long-term efficacy of surgical treatment.
(a) Principles of adjuvant chemotherapy
1. There may be occult surviving tumor cells in the circulation and microscopic foci of cancer cells locally, distantly or both.
2.Treatment is most effective when the mass is small and the cell kinetics are appropriate, i.e., chemotherapy is more effective when the tumor load is reduced or the growth index ratio is large.
3.With agents that have been shown to be effective for this tumor.
4. Cytotoxic therapy shows a dose-response relationship, so the maximum tolerated dose must be given and the course of treatment must be limited to killing all tumor cells.
(B) The main indications for chemotherapy
1.Applicable to postoperative chemotherapy for patients with Dukes’ stage B and C.
2.Local chemotherapy.
3. Palliative chemotherapy for patients with advanced disease.
(C) Contraindications to chemotherapy
1.Patients with hyperemic state.
2.Patients with severe cardiovascular disease or renal dysfunction.
3, the blood picture is not applicable to chemotherapy.
(D) The mode of chemotherapy
1.Systemic intravenous chemotherapy.
2.hepatic artery cannulation chemotherapy: liver metastasis of colorectal cancer can cause progressive liver destruction and finally lead to death of patients. The median survival of patients with untreated colorectal cancer liver metastases is 2.5 months to 6 months. Many drugs such as 5-Fu and 5-Fu-DR (fluorouracil deoxyriboside) are metabolized in the liver to become less toxic products, thus increasing the concentration of such drugs by hepatic arterial infusion and decreasing the systemic toxicity, and the efficiency of hepatic arterial cannulation chemotherapy is more than 50%, which is much higher than that of 5-Fu intravenous administration (about 20%). This is the mechanism of applying chemotherapeutic drugs through hepatic artery for the treatment of liver metastasis cancer.
3.Portal vein placement chemotherapy, intraoperative insertion of catheter through small intestinal mesenteric vein or transverse colonic vein or gastric omental vein 5cm away from pylorus, the time of portal vein infusion is mostly arranged 6 hours after completion of intestinal anastomosis, 5-Fu600mg/m2+heparin sodium 5000u dissolved in 5% glucose solution, 24h continuous infusion in portal vein, the drip rate is 40m1/h, 7 days continuous infusion.
4.Intraoperative adjuvant intestinal cavity chemotherapy: intestinal cavity infusion of chemotherapy drugs, one of the measures to reduce anastomotic recurrence, is an important part of anorectal tumor surgery tumor-free technology. The method is: firstly, the two ends of the intestinal segment ready to be resected are each 8-10cm away from the tumor margin with a cloth belt looped around the intestinal canal during surgery. In case of rectal cancer, the anus will be occluded, and then 5-Fu 30mg/kg (dissolved in saline 500ml) will be injected into the intestinal cavity of the mass, and then ligated after 30 minutes to cut off the artery supplying the intestinal segment that should be resected, and the operation will be completed according to the conventional steps.
5, intraperitoneal chemotherapy: the drug concentration in the abdominal cavity is increased by direct intraperitoneal administration, and the potency is maintained for a long time. Meanwhile, the drug concentration formed by this intraperitoneal administration is hundreds of times higher than that of intravenous administration, and the drug is absorbed through the portal system, which has better therapeutic effect on cancer cells in the portal system and liver. The commonly used chemotherapeutic drugs are 5-Fu, MMC (mitomycin), ADM (adriamycin), DDP (cis-chloroplatinum), MTX (methotrexate), etc. The combination of 5-Fu and MMC has a synergistic effect.
It can directly kill cancer cells and is a commonly used protocol in clinical practice. The specific method is: chemotherapeutic drugs are diluted with 1.5L~2L liquid, warmed to 37℃, and clamped for 4 hours after one intraperitoneal perfusion, so that the drugs are evenly distributed in the abdominal cavity, touching all parts and maintaining a certain action time, and then negative pressure is used to suck out the chemotherapeutic solution as much as possible to reduce the accumulation of drugs. Generally, once a day for 5 days as a course of treatment.
6.Arterial intubation chemotherapy: If advanced rectal cancer cannot be treated by radical surgery or recurrence of metastasis occurs within a short time after palliative tumor resection, arterial intubation chemotherapy can provide a better way for its treatment. At the same time, the use of arterial cannulation chemotherapy is less toxic, reduces systemic toxic reactions, shortens the treatment time, and can improve the surgical resection rate if applied before surgery.
V. Treatment of colorectal cancer liver metastasis
(a) The status and principles of surgical treatment Today, there are more and more reports that the 5-year survival rate of liver metastases from colorectal cancer can reach 20%-30% with the application of various corresponding surgical treatments. Surgical resection of liver metastases from colon and rectal cancer has been recognized as an active and effective method. It is generally considered that surgical treatment can be given priority in the following cases.
①When the metastatic lesion is a single nodule or the extent of involvement is small, i.e. the lesion is confined to one lobe or one and a half sides of the liver.
②Extrahepatic lesions have been excluded, the primary lesion has been eradicated and there is no sign of local recurrence.
③The patient is in good general condition, without significant cardiac, pulmonary, hepatic or renal dysfunction, and can tolerate surgery.
④The survival time after reoperation and the risk of surgery were fully considered and weighed.
⑤The surgeon is required to have rich experience in liver surgery and be competent in various types of complex liver surgery.
(II) Modern comprehensive treatment In addition to surgical resection for liver metastatic lesions of colon and rectal cancer, modern comprehensive treatment should be emphasized. The recommended methods are mainly as follows
① When liver resection is not appropriate due to extensive lesions or underlying liver lesions during surgery, hepatic artery ligation is feasible, and this method is still effective in the near future.
This method can be performed under ultrasound guidance, or regional perfusion therapy through interventional radiation, or embolization of giant lesions, followed by second-stage resection after the mass has shrunk and the systemic condition allows.