Overview of Rectal Cancer
Rectal cancer refers to cancer from the dental line to the junction of the rectosigmoid colon. It is one of the most common malignant tumors of the digestive tract. Rectal cancer is located low and is easily diagnosed by digital rectal examination and sigmoidoscopy. However, due to its location deep into the pelvic cavity and complex anatomical relationships, it is difficult to complete the operation and the postoperative recurrence rate is high. Middle and lower rectal cancer is close to the anal sphincter. It is difficult to preserve the anus and its function during surgery, which is a difficult problem in surgery. It is also the most controversial disease in surgical methods. The median age of onset of rectal cancer in my country is around 45 years old. The incidence rate in young people is increasing.
Diagnosis
In general, patients with stool bleeding should be highly vigilant in clinical practice and should not be rashly diagnosed as "dysentery", "internal hemorrhoids", etc. Further examinations must be conducted to rule out cancer. possibility. For the early diagnosis of rectal cancer, attention must be paid to the application of digital rectal examination, proctoscopy or sigmoidoscopy.
(1) Digital rectal examination About 90% of rectal cancers, especially cancers in the lower rectum, can be discovered by digital examination alone. However, there are still some doctors who do not perform this routine examination on patients with suspected rectal cancer, resulting in delayed diagnosis and treatment. In fact, this diagnostic method is simple and feasible. A digital rectal examination can also determine the size and degree of infiltration of the palpable mass, whether it is fixed, and whether there is an implanted mass outside the intestinal wall or in the pelvic cavity.
(2) Proctoscopy or sigmoidoscopy should be performed after digital rectal examination to assist diagnosis under direct vision, observe the shape of the mass, upper and lower edges, and distance from the anal verge, and take The mass tissue was subjected to pathological biopsy to determine the nature of the mass and its degree of differentiation. Cancer is located in the middle and upper part of the rectum and cannot be touched with fingers. Sigmoidoscopy is a better method.
(3) Barium enema and fiberoptic colonoscopy are not very helpful in the diagnosis of rectal cancer, so they are not included as routine examinations and are only used to exclude multiple colorectal tumors.
Treatment measures
The treatment of rectal cancer is still based on surgery, supplemented by chemotherapy, and radiotherapy plays a certain role.
(1) Surgical treatment is divided into two types: radical and palliative.
1. Radical surgery The surgical method depends on the location of the cancer in the rectum. There are two systems in the rectal wall: submucosal lymphatic plexus and myenteric lymphatic plexus. Metastasis of cancer cells in the lymphatic system in the intestinal wall is rare. Once cancer cells penetrate the intestinal wall, they spread to the lymphatic system outside the intestinal wall. Generally, the paraintestinal lymph nodes at the same level or slightly higher than the cancer are first involved, then gradually upward to involve the middle lymph node group accompanying the superior hemorrhoidal artery, and finally to the lymph node group next to the inferior mesenteric artery (Figure 1). The above-mentioned upward lymphatic metastasis is the most common metastasis mode of rectal cancer. If the cancer is located in the lower rectum, the cancer cells can also invade the obturator lymph nodes laterally along the lymphatic vessels of the levator ani muscle and pelvic wall fascia, or flow to the internal iliac lymph nodes along the middle hemorrhoidal artery. Sometimes cancer cells can also pass downward through the levator ani muscle and drain along the inferior hemorrhoidal artery to the lymph nodes in the ischiorectal fossa and inguinal lymph nodes. Since the lymphatic metastasis direction of upper rectal cancer is almost always upward, surgical resection of cancer tumors adjacent to and above this plane is The purpose of radical cure can be achieved by removing the lymphoid tissue, and the operation has the possibility of preserving the anal sphincter. Although the lymphatic metastasis of lower rectal cancer is mainly upward, there is also the possibility of lateral metastasis to the internal iliac lymph nodes and obturator lymph nodes. Radical surgery needs to include the tissues around the rectum and anal canal and the levator ani muscle, so the anal sphincter cannot be preserved. The specific surgical methods are as follows:
Figure 1 Drainage pathways of the lymphatic system inside and outside the rectal wall
The dotted line network shows the lymphatic system within the intestinal wall
1. Sigmoid artery 2 .Superhaemorrhoidal artery 3. Left colic artery 4. Internal iliac lymph nodes 5. Obturator lymph nodes 6. Levator ani muscle 7. Inguinal lymph nodes
(1) Combined abdominoperineal resection (Miles surgery): suitable for For lower rectal cancer less than 7cm from the anal verge, the resection scope includes the sigmoid colon and its mesentery, rectum, anal canal, levator ani muscle, tissue in the ischiorectal fossa and perianal skin, and blood vessels at the root of the inferior mesenteric artery or the branch of the left colic artery. The lower part is ligated and cut off, and the corresponding para-arterial lymph nodes are cleaned. A permanent colostomy (artificial anus) is made in the abdomen, and the perineal wound is sutured or packed with gauze. This surgery is complete resection and has a high cure rate (Figure 2).
Figure 2 Combined abdominoperineal resection for rectal cancer
The dotted line indicates the resection range
1. Periaortic lymph nodes 2. Sigmoid mesocolon lymph nodes 3. Anus Supralevator lymph nodes 4. Ichioanal space lymph nodes
(2) Low abdominal resection and extraperitoneal primary anastomosis, also known as anterior resection of rectal cancer (Dixon surgery), is suitable for distance from the anal verge For upper rectal cancer over 12cm, the sigmoid colon and most of the rectum are removed intraperitoneally, the rectum under the peritoneal reflection is freed, and the cut ends of the sigmoid colon and rectum are anastomosed extraperitoneally. This surgery is less invasive and can preserve the original anus, which is ideal. If the cancer is large and has infiltrated surrounding tissue, it should not be used.
(3) Anal sphincter-preserving rectal cancer resection: suitable for early-stage rectal cancer 7 to 11 cm from the anal verge. If the cancer is large, poorly differentiated, or the main upward lymphatic vessels have been blocked by cancer cells and there is transverse lymphatic metastasis, this surgical method will not be completely resected, and it is still better to perform combined abdominoperineal resection. Currently used anal sphincter-preserving resections for rectal cancer include stapler-assisted anastomosis, transabdominal low resection-transanal eversion anastomosis, transabdominal free resection-transanal pull-out resection anastomosis, and transabdominal transsacral resection. Select according to specific circumstances.
2. Palliative surgery: If the cancer has severe local infiltration or extensive metastasis and cannot be cured, in order to relieve the obstruction and reduce the patient's pain, palliative resection can be performed, and the intestinal segment with cancer can be resected to a limited extent. , suture the distal end of the rectum, and take the sigmoid colon as a stoma (Hartmann operation). If this is not possible, only sigmoid colostomy is performed, especially in patients with intestinal obstruction.
(2) Chemotherapy is the same as colon cancer.
(3) Radiotherapy The role of radiotherapy in the treatment of rectal cancer has been increasingly valued. There are two types: comprehensive treatment combined with surgery and radiotherapy alone.
1. Comprehensive treatment combining surgery and radiotherapy ① Preoperative radiotherapy can control the primary tumor, control lymph node metastasis, improve the resection rate and reduce local recurrence, and is suitable for stage III (Dukes grade C) rectal cancer . Using two fields of pelvic front and back cross-sectional irradiation, the radiation dose can reach 40-45Gy (4000-4500rad), and surgery is performed 3 weeks after radiotherapy; ② Postoperative radiotherapy is suitable for lymph node metastasis confirmed by pathological examination, and the cancer has obviously infiltrated into the intestine. Outside the wall, unresectable lesions remain in the pelvic cavity. Generally, 1 to 2 months after the operation, after the perineal wound has healed, pelvic field irradiation is used, both anterior and posterior. Sometimes perineal field irradiation is also added, and the radiation dose can reach 45 to 50 Gy (4500 to 5000 rad).
(4) Local tumor freezing, laser and cauterization treatment: Patients with advanced rectal cancer accompanied by signs of incomplete intestinal obstruction can try local tumor freezing or cauterization (including electrocautery and chemical cauterization) to treat tumor tissue. shrink or fall off, temporarily relieving obstruction symptoms. In recent years, laser treatment has been carried out. Nd-YAG laser with a power of 65W is used to irradiate local tumor tissue at points. In case of bleeding, the power of 40W is used to focus irradiation around the bleeding point to stop bleeding. The irradiation is repeated every 2 to 3 weeks. In individual cases, Tumors can be seen shrinking, symptoms can be temporarily relieved, and it can be used as a form of palliative care.
(5) Treatment of patients with metastasis and recurrence
1. Treatment of local recurrence If the local recurrence is limited in scope and there is no recurrence or metastasis in other locations, surgical exploration can be performed , strive for resection. If the recurrence is limited to the center of the perineal incision and has not extended to the ischial tuberosities on both sides, extensive resection is possible. If the perineal nodule or mass is a pelvic recurrence extending to the lower pole of the perineum, surgery is not suitable because the lesion cannot be completely removed and the tumor tissue will be cut instead, leaving a wound that will not heal for a long time.
Radiotherapy is used for recurrent lesions in the pelvis, with each course of 20Gy (2000rd), which can temporarily relieve pain symptoms.
2. Treatment of liver metastases. In recent years, many studies have confirmed that the effect of surgical resection of rectal cancer metastases is not as pessimistic as originally thought. If the liver metastases can be resected simultaneously with the primary lesions, the survival rate can be improved. For single metastases, segmental or wedge resection of the liver is feasible. If there are multiple liver metastases that cannot be surgically removed, dearterialization measures are first used, that is, the hepatic artery is ligated to necrosis the liver tumor, and then a catheter is inserted through the distal end of the ligated hepatic artery, and fluorouracil and mitomycin are injected through it; Hepatic artery embolization can also be used to significantly reduce the size of the tumor.
However, the above treatments are contraindicated in patients with obvious jaundice, severe liver function abnormalities, portal vein infarction, and patients over 65 years old. Radiation therapy can improve symptoms in some patients. In recent years, there have been reports of using radiofrequency hyperthermia to treat liver metastases. Oral metronidazole can also increase the tumor suppressor effect, but the efficacy is still being summarized.
Clinical manifestations
The clinical features of early rectal cancer are mainly blood in the stool and changes in defecation habits. When the cancer is limited to the rectal mucosa, blood in the stool accounts for 85% of the early symptoms. Unfortunately, it is often Not taken seriously by patients. An anus finger examination was performed at that time, and most of the masses were palpable. In addition to the common systemic symptoms such as loss of appetite, weight loss, and anemia, patients with intermediate and advanced rectal cancer also had cancerous tumors such as increased frequency of defecation, incomplete defecation, frequent bowel movements, and tenesmus. Symptoms of local irritation. The enlargement of cancer can cause the intestinal lumen to become narrow and cause signs of intestinal obstruction. Cancer invades surrounding tissues and organs, causing symptoms such as difficulty urinating, frequent urination, and painful urination; it invades the presacral nerve plexus, causing sacrococcygeal and waist pain; and when it metastasizes to the liver, it causes hepatomegaly, ascites, jaundice, and even malignant fluid. Quality performance.
Prognosis
According to the Shanghai Cancer Institute's analysis of the survival rate of 99,552 cases of malignant tumors in Shanghai from 1972 to 1979, 5 of 6,905 cases of colorectal cancer (including rectal cancer) The annual survival rate is 27.8%, which is significantly higher than the 5-year survival rate of malignant tumors of the stomach, lung, liver, esophagus and pancreas. The Affiliated Cancer Hospital of Shanghai Medical University followed up 1,385 cases of surgically resected colorectal cancer. Among them, the 5-year and 10-year survival rates of 1,061 cases of rectal cancer were 47.20% and 40.28%, respectively, which were slightly lower than the 54.63% and 53.90% of 324 cases of colon cancer. ; The median survival time of 118 patients with rectal cancer who underwent palliative resection was 15 months (range 3 to 50 months); the median survival time of 202 patients with unresected rectal cancer was 8 months (range 1 to 96 months). moon). Similarly, the prognosis of rectal cancer has nothing to do with the patient's gender and age, but is closely related to the course of the disease, the extent of cancer infiltration, the degree of differentiation, and the presence of metastasis.
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