Peritoneal metastatic cancer

　　First, Etiology

　　The main site of onset is the abdominal organs, with ovarian cancer and pancreatic cancer being the most common, followed by stomach, uterus, colon, and lymphatic system. Extrapleural lung cancer and breast cancer can also metastasize to the peritoneum, and 30% of leukemia patients may have peritoneal involvement. The presence of free abdominal cancer cells and residual microlesions is a key factor in the recurrence and peritoneal metastasis of abdominal malignant tumors after surgery, as it has a strong regenerative ability and is highly prone to implantation on the peritoneal surface of surgical anatomical injuries and on the exposed subcutaneous connective tissue, thereby causing local recurrence and metastasis after surgery. The sources of free abdominal cells include:

　　1. Tumor cells penetrate the serosa of abdominal organs and directly fall into the abdomen. The positive rate is proportional to the biological characteristics of the tumor and the area of serosal infiltration.

　　2. Cancer cells that fall into the gastrointestinal cavity during surgery are carried into the abdomen with gastrointestinal fluid through the residual end.

　　3. Cancer emboli in the blood and lymphatic vessels that are cut off in the surgical area flow into the abdomen with blood and lymph fluid.

　　The residual microlesions within the abdomen include: microscopic cancer foci that cannot be completely surgically removed; after surgery, the cancer cells within the abdominal cavity are coagulated by纤维素-like substances in the surgical area to form a protective layer, making it difficult for immune cells to engulf them, resulting in residual small cancer foci. In addition, due to the impact of surgery and anesthesia, the body's immune function decreases, cancer cells proliferate, form masses, and ultimately lead to local recurrence and metastasis in the abdominal area.

　　In clinical practice, it is sometimes difficult to identify the primary tumor site even after various examinations, as abdominal metastatic tumors may appear without a known source.

　　Second, Pathogenesis

　　Abdominal metastatic tumors can arise from various organs and systems throughout the body, with common modes of metastasis including: metastasis through blood vessels or lymphatic vessels from tumors outside or inside the abdomen; direct implantation or infiltration metastasis from abdominal organs or abdominal wall tumors. Among them, laparoscopic surgery or laparotomy, and tumor resection surgery causing implantation are clinical situations that are more common and important as a mode of metastasis.

　　More than 75% of peritoneal metastatic cancers are metastatic adenocarcinomas. When the cancer of the abdominal organs involves the serosa, tumor cells fall off, spread and implant on the surface of the peritoneum, omentum, or mesentery, grow and reproduce, and are surrounded by connective tissue of the peritoneum, forming metastatic nodules of varying sizes. These nodules can be granular or nodular. Peritoneal metastatic tumors often cause bloody ascites and extensive adhesions of organs, leading to the death of patients.

　　If the tumor invades the liver or bile duct, jaundice may occur. When the mass compresses the gastrointestinal tract or causes intestinal torsion or intussusception due to the mass, symptoms such as pain, vomiting, bloating, and obstruction may appear. It can also lead to ascites, which is usually referred to as malignant ascites caused by tumor. It is mostly caused by direct infiltration of malignant tumors, and the occurrence of ascites generally indicates that the disease has entered the advanced stage. Secondly, due to the influence of the tumor, the patient's immune function is reduced, making it easier to be infected. If the peritoneum is infected by pathogenic bacteria, it can lead to purulent infection complications.

　　The manifestations of abdominal metastatic tumors vary due to different tissue origins and tumor pathological characteristics, in addition to the manifestations of the primary tumor. Peritoneal metastatic cancer mainly manifests as ascites, abdominal distension, abdominal pain, anemia, and weight loss. Their common manifestations are:

　　1. Abdominal distension and ascites:Ascites is the most common and early clinical symptom of abdominal metastatic tumors, and the amount of ascites is usually not large. It is different from the severe abdominal distension caused by massive ascites in patients with liver cirrhosis, tuberculous peritonitis, and nephropathy. However, if it is accompanied by portal vein metastasis or liver metastasis and liver failure, it may also manifest as massive ascites. Physical examination may reveal mobile dullness. Ascites is usually colorless or slightly yellowish, slightly cloudy liquid. If accompanied by tumor necrosis and hemorrhage, it may be bloody and exudative, with a high protein content. Pathological examination of ascites may detect tumor cells.

　　2. Abdominal mass:Abdominal masses caused by abdominal metastatic tumors are often multiple and can be located in various parts of the abdomen. They often have a certain degree of mobility, which varies depending on the location of the tumor in the peritoneum. The texture of the mass varies depending on the pathological nature of the tumor. Sometimes, when the tumor invades the abdominal wall, it may present as a fixed mass on the abdominal wall, which is often hard and has marked tenderness.

　　3. Digestive system symptoms:They are often manifested as loss of appetite, sometimes accompanied by nausea, vomiting, abdominal pain, and diarrhea. If the tumor invades the liver or bile duct, jaundice may occur. When the mass compresses the gastrointestinal tract or causes intestinal twisting or intussusception, symptoms such as pain, vomiting, distension, and obstruction of the intestine may occur. Some patients may be diagnosed with acute intestinal obstruction and undergo surgery for a clear diagnosis.

　　4. General symptoms:They are often manifested as fatigue, weight loss, anemia, and cachexia.

　　5. Symptoms of primary disease:The symptoms of primary diseases vary due to different tissue, organ origins and pathological types, such as upper gastrointestinal bleeding and pyloric obstruction in gastric cancer patients; jaundice, liver failure, and portal hypertension in liver cancer patients; and abdominal metastatic tumors from extraperitoneal organs often present mainly with the symptoms of the primary disease. Even more obvious symptoms of abdominal metastasis may be mistakenly considered as late-stage manifestations of the primary tumor, leading to the abandonment of treatment. In a very few cases, the patient may be diagnosed with abdominal metastatic tumor or found to have abdominal metastasis during post-mortem examination, but the source of the primary disease cannot be determined.

　　The prevention of abdominal metastatic tumors mainly relies on surgical procedures and strict adherence to the principles of tumor-free techniques during laparoscopic surgery. At the same time, continuous intraperitoneal hot perfusion chemotherapy can be applied. For tumors originating from organs outside the abdomen, it is necessary to reduce compression during clinical examinations to prevent hematogenous and lymphatic metastasis. Particularly, during invasive puncture examinations and endoscopic examinations guided by B-ultrasound, CT, and other methods, indications should be carefully considered, operations should be gentle to prevent iatrogenic metastasis. Of course, early diagnosis and early treatment of various types of tumor patients are the most important preventive measures.

　　First, Laboratory examination

　　The general laboratory examination of this disease often shows the characteristics of the primary tumor, such as elevated AFP in patients with liver cancer, elevated CEA in patients with colorectal cancer, positive occult blood in stools when accompanied by gastrointestinal bleeding, anemia in some cases, and endocrine abnormalities in tumors originating from the department of gynecology and obstetrics, etc.

　　1. Cytological examination:Cellular examination by aspiration of ascitic fluid through abdominal puncture, with a positive rate of 50% to 80%. The following 3 points can improve the detection rate of ascitic cancer cells: ① Look for it repeatedly; ② Draw a sufficient amount of ascitic fluid, at least 500ml; ③ Have the patient turn over repeatedly before drawing ascitic fluid to make it easier to aspirate the settled cancer cells.

　　2. Biopsy:Pathological examination of tissue under the direct vision of peritoneoscopy is currently the most accurate examination method.

　　3. Blood routine and plasma protein:It may have red blood cells, decreased hemoglobin, and decreased plasma albumin.

　　4. Ascitic fluid examination:Ascitic fluid examination is the simplest, fastest, most convenient, and least damaging clinical examination method. It can be repeated for patients suspected of having abdominal metastatic tumors. By examining the cells shed from the ascites, an accurate diagnosis can be made, and the primary lesion can be traced according to the characteristics of the tumor pathological type.

　　In summary, tissue biopsy is the most reliable method for diagnosing this disease. Tissue samples can be obtained through abdominal puncture, laparoscopy, or laparotomy. Diagnostic laparotomy for the sole purpose of obtaining tissue samples is rarely used, and most tissue samples are obtained during therapeutic surgery.

　　Second, Imaging examination

　　1. Ultrasound examination

　　(1) Ascites: Ascites and adhesion of abdominal organs are common, and the ultrasound shows a free floating anechoic area in the abdominal cavity, and the intestinal tubes adhere in clusters attached to the posterior abdomen.

　　(2) Irregular thickening of the peritoneum: The ultrasound image shows the thickened peritoneum as a high echo strip-like change, which is often irregular in shape.

　　(3) Tumorous nodules in the abdominal cavity: Tumorous nodules in the abdominal cavity often occur with ascites and are displayed clearly, most commonly seen in the right abdominal wall and pelvic wall, can also be located in the upper abdominal midline, the nodules are not clearly demarcated from the abdominal wall, and they protrude inward, in the absence of ascites, solid, cystic, or mixed mass echoes can be seen, and some tumors may show the original tumor echo characteristics and multiple mesenteric lymph node enlargement in the abdominal cavity.

　　2. CT scan

　　It can show the location, size, nature, and ascites of metastatic cancer, which has great value in the diagnosis of the disease. It can localize the disease and understand the number, texture, blood supply of the mass, and help to find the primary lesion.

　　The CT manifestations of peritoneal metastatic tumors include: ascites, thickening of the parietal peritoneum, dirty, nodular, cake-like, and mass-like changes of the mesentery and omentum, cystic space-occupying changes in the abdominal cavity, thickening of the small intestinal wall and displacement of the small intestine. Many authors believe that CT can be the first choice for the examination of peritoneal metastatic tumors.

　　(1) Ascites: Uniform water-like density shadow between abdominal organs (Figure 5A), a small amount of ascites accumulates in the renal and liver recess or the lateral margin of the liver. When there is a large amount of ascites, it surrounds the entire abdominal organs and can enter the lesser omentum sac.

　　(2) Irregular thickening of the peritoneum: Normally, CT does not show the anterior peritoneum, and the posterior peritoneum only shows a pencil-drawn thin line. However, the thickened peritoneum of peritoneal metastatic tumors can be宽带状, nodular or mass-like, with宽带状 as the most common, followed by nodular. This may be related to the process of multiple seeding of tumor cells after growth and fusion. The宽带状 tumor lesions may be the manifestation of nodular fusion. In terms of location, it is most common in the right abdominal wall, followed by the left abdominal wall and anterior abdominal wall.

　　(3) Changes of mesentery and omentum:

　　① Dirty-like changes: Normally, the mesentery or omentum with uniform fat density appears regional multiple small spots or short strips of dirty-like density shadows.

　　② Nodular changes: Nodular soft tissue density shadows are seen within the fat density mesentery or omentum.

　　③ Cake-like omentum or mesentery: The omentum or mesentery loses fat density and is replaced by cake-like soft tissue density shadow.

　　The above three manifestations can coexist. The omentum or mesentery with fine dirt-like texture can enlarge into nodular shape, and then fuse into a cake-like shape.

　　(4) Multiple or solitary cystic space-occupying changes in the peritoneal cavity: Manifested as multiple or solitary cystic changes in the peritoneal cavity, with thin cyst walls and water-like density inside, with space-occupying effects. This can be differentiated from simple ascites.

　　(5) Thickenings of the mesentery margin: Manifested as thickening of the small intestinal wall, prominent at the mesentery margin, involving part or most of the intestinal wall. The diagnosis of peritoneal cavity metastatic tumor requires the combination of the patient's history of primary disease and typical CT findings, and needs to be differentiated from peritoneal tuberculosis and primary peritoneal tumors, because the CT signs of the three have a significant overlap.

　　3. MRI:Peritoneal metastatic cancer can manifest as direct spread along the mesenteric surface, implantation in the peritoneal cavity, hematogenous metastasis, and lymphatic metastasis. Enhanced fat suppression can show obvious enhancement of solid peritoneal metastatic lesions, with generally irregular boundaries. The implantation and metastasis lesions in the peritoneal cavity are manifested as multiple scattered nodular enhancement foci.

　　4. X-ray examination:For the diagnosis of this disease, gastrointestinal barium meal and barium enema can be performed. Indirect signs such as compression and displacement of the gastrointestinal tract may be seen in some patients. If the tumor is primary in the gastrointestinal tract, the primary lesion can be found. Selective arteriography may sometimes show new blood vessels of the tumor, but there are no special diagnostic signs for this disease. Ultrasound examination of the abdomen often shows positive findings, which can display multiple solid masses, occasionally with cystic changes, and at the same time, ascites can be seen. If necessary, fine needle aspiration biopsy can be performed under ultrasound guidance to confirm the diagnosis and pathological type.

　　5. Laparoscopic examination:For patients with unclear diagnosis of abdominal mass accompanied by significant ascites, laparoscopy can be used for examination. After aspiration of ascites, multiple masses or nodules are often seen on the parietal peritoneum and visceral peritoneum. Biopsy of nodules or masses under laparoscopy is a very effective method for confirming the diagnosis of peritoneal tumor metastasis.

　　The diet of patients with peritoneal metastatic cancer should be light and easy to digest, with an emphasis on eating more vegetables and fruits, a reasonable diet, and ensuring adequate nutrition. In addition, patients should also pay attention to avoiding spicy, greasy, and cold foods.

　　1. Treatment

　　In the past, abdominal metastatic tumors were often considered as late-stage cancer and treatment was abandoned. In recent years, with the development of imaging, pathology, surgery, and tumor treatment, there has been a new understanding of this, and active and effective treatment has been started, achieving certain efficacy.

　　1. Peritoneal tumor cell reduction surgery:Peritoneal tumor cell reduction surgery aims to resect as much of the peritoneum with tumor lesions and the peritoneum that may be invaded by the tumor, as well as the mesentery and omentum formed, in order to reduce the tumor burden, alleviate symptoms, improve the quality of life, and extend the survival period. There are 6 common surgical techniques: omentectomy and splenectomy; left upper quadrant peritoneal resection; right upper quadrant peritoneal resection; lesser omentum and gallbladder resection; pelvic peritoneal resection; and gastric antrum resection. Different surgical techniques are selected based on the size and distribution of the cancer lesions, but the effect of simple surgery is very poor.

　　Currently, the indications for peritoneal tumor cell reduction surgery are: peritoneal tumors caused by low-grade gastrointestinal tumors; peritoneal tumors caused by medium-grade small-volume gastrointestinal tumors; peritoneal tumors caused by cell leakage during gastrointestinal tumor perforation or resection; primary colorectal cancer with invasion of adjacent organs and tissues; peritoneal tumors caused by mesothelioma, ovarian cancer, and low-grade sarcoma, etc.

　　The entire operation consists of 6 parts: omentectomy and splenectomy; left upper peritoneal resection; right upper peritoneal resection; lesser omentum, gallbladder, and omental bursa resection; pelvic peritoneal resection; and gastric antrum resection. Depending on different situations, part or all of the surgery can be chosen: patients with small-volume tumors, primary ovarian, appendiceal, or colonic rectal low-grade cystadenoma and mesothelioma need to undergo all the above surgeries; patients with ovarian malignant tumors with peritoneal metastasis, advanced rectal cancer, rectosigmoid junction cancer penetrating the intestinal wall with peritoneal dissemination all need pelvic peritoneal resection; since the cells of appendiceal, colonic, and ovarian tumors can reach the diaphragm through the lymphatic vessels, these patients need left and right upper peritoneal resections. The omentum is often removed with the spleen, and it is not necessary to remove it if the spleen is not invaded. Similarly, if the gallbladder is not invaded, it does not need to be removed with the lesser omentum.

　　The specific surgical method is: the patient lies on their back in a lithotomy position, with a pad placed under the sacrum to avoid necrosis of the skin and muscle during surgery. Placing the sole on a footboard can reduce pressure on the gastrocnemius muscle. The lower limbs are placed on an alternating pressure device to prevent the formation of venous thrombosis. The abdominal incision starts at the xiphoid process and ends at the pubic bone, with the excision of the xiphoid process and the use of an abdominal retractor to widely expose the peritoneal cavity. The tumor is usually separated using a spherical electrocautery handle (ball-tipped electrosurgical handpiece), and钝性分离the boundary between the tumor and normal tissue under high pressure to make the tumor evaporate electrically. The commonly used diameter of the spherical electrocautery handle is 2mm, and a diameter of 5mm can be selected if rapid resection is required. A large amount of feather-like particles and smoke appear due to tissue carbonization and electricalization, and a smoke evacuation device is needed to keep the surgical field clear and the operating room smoke-free.

　　(1) Greater omentum and spleen resection: Lift the greater omentum and separate it from the transverse colon to expose the pancreas, probe the surface of the spleen for tumors, and pull the spleen away after confirming there are no tumors. Separate the pre-peritoneal fascia of the pancreas, ligate and cut the splenic artery and vein at the tail of the pancreas, and perform a splenectomy.

　　(2) Left upper peritoneal resection: Begin by separating the peritoneum behind the rectus sheath at the incision margin, exposing the upper left abdomen by clamping a hemostat every 10 cm. Strip all tissues below the left diaphragm, exposing the left adrenal gland, the superior aspect of the pancreas, and the cranial aspect of the renal fascia. To fully expose the upper left abdomen, the colonic splenic flexure needs to be freed and pulled inward. The vessels between the diaphragm and the peritoneum must be coagulated before being cut to prevent bleeding. Sometimes, the tumor invades the head of the pancreas and requires cutting the small branch of the left gastric artery, and it should be avoided to damage the main branch of the left gastric artery to maintain the blood supply of the stomach.

　　(3) Right upper peritoneal resection: Begin from the stripping incision of the rectus sheath, using a spherical electrocautery handle to electrocoagulate the tumors on the liver diaphragmatic surface, falciform ligament, round ligament, and solitary tumors on the liver surface. Blood transfusion tumors on the surface of the liver are removed by electrocoagulation. Tumors on the surface of the Glisson sheath require simultaneous sharp dissection and electrocoagulation methods. Then, resect the right renal fascia and the surface tumor of the right adrenal gland. At this time, attention should be paid to the protection of the inferior vena cava and the caudate vein of the liver. Tumors often have a close adhesion with the central part of the diaphragm, and elliptical resection of the diaphragm is required, and the fibrous tissue involved by the tumor should also be removed, and the defect of the diaphragm should be sutured intermittently. Respiratory distress caused by this is rare.

　　(4) Small omentum, gallbladder, and omental bursa resection: The gallbladder is often resected retrogradely. Tumors often seriously invade the portal tissue, and resection of the tumor from the gallbladder bed to the duodenum is required, at this time, the use of a spherical electrocautery handle may cause severe injury, and it is common to use hemostats to clamp the tumor and cut it off with an electric knife above the clamp. To continuously resect the small omentum, it is necessary to separate the caudate lobe and the left lobe of the liver along the venous ligament groove, at this time, attention should be paid to the injury of the caudate lobe to prevent massive hemorrhage. In addition, the left hepatic artery may originate from the left gastric artery and pass through this area, so it also needs to be protected. When stripping the omentum, protect the branches of the left gastric artery and the coronary vein, separate the small omentum fat, and use the thumb and index finger to apply pressure to help distinguish these vessels. Separate the lesser curvature of the stomach in a clockwise direction, retaining sufficient small omentum fat while removing the tumor. Due to the many branches of the vagus nerve entering the gastric antrum being cut, a pyloroplasty or gastrojejunal anastomosis is required to prevent postoperative gastric retention.

　　(5) Pelvic peritoneal resection: Begin by stripping the peritoneum from the lower abdominal incision, exposing the rectal and bladder muscular layers, and removing the tumor from the peritoneum and extraperitoneal fat. Cut the round ligaments on both sides at the inguinal ring. Perform a complete resection of the pelvic peritoneum starting from the edge of the pelvis, separating and protecting both ureters. Cut off the sigmoid colon at its middle with a linear stapler. Ligate and cut the left and right uterine veins, suture and cut the uterine artery, and remove the uterus. Separate the vaginal fornix, remove the tumor at the blind tube, and close the vaginal stump with absorbable sutures. Perform the colo-rectal anastomosis with a stapler, if there is high tension at the anastomosis site, it is necessary to relieve the tension of the left half of the colon. After anastomosis, fill the pelvic cavity with water to check the sealing of the anastomosis, check for tension at the anastomosis site with hands, and perform rectal examination to determine if there is bleeding at the anastomosis.

　　(6) Gastric antrum resection and gastrointestinal reconstruction: The gastric antrum, like other more fixed tissues in the peritoneum, is easily extensively invaded by tumors and should be completely resected. The right gastric artery and the first part of the duodenum are separated, and the stomach and duodenum are transected above and below the tumor, followed by a gastrojejunal anastomosis. A stoma tube is placed at the distal end of the duodenum to prevent duodenal fistula after surgery.

　　Routine intraperitoneal chemotherapy is performed after surgery. A drainage tube is placed under the left and right diaphragms and in the pelvic cavity, and an abdominal perfusion tube is placed below the small intestinal loop for intraperitoneal chemotherapy. Thoracic drainage tubes are placed in the left and right pleural cavities to prevent pleural effusion caused by intraperitoneal chemotherapy after surgery. The patient's condition is closely observed after surgery. The warm abdominal perfusion fluid is retained for 4 hours and then released. The intraperitoneal perfusion of chemotherapy drugs is performed once every 8 hours.

　　Although tumor cell reductive surgery is technically feasible and has achieved certain effects in clinical practice, it has certain complications due to its complexity and high trauma, and there are certain technical requirements. Clinical application should be cautious.

　　2. Intraperitoneal chemotherapy:It is the main method for treating peritoneal metastatic cancer.

　　(1) Pharmacokinetic advantages: ① The peritoneal tumor is directly immersed in a high-concentration, strong-penetrating anticancer drug solution, enhancing the drug's killing ability against tumor cells; ② After administration, the drug is mainly absorbed into the liver through the portal vein system, metabolated into non-toxic or low-toxic forms through the first-pass liver effect and enters the systemic circulation, reducing the drug's toxic effects on the body after metabolism and improving the body's tolerance; ③ Intraperitoneal chemotherapy increases the concentration of chemotherapy drugs in the portal vein system and liver blood, while the liver is the most common organ for distant metastasis of cancer.

　　(2) Common chemotherapy drugs: cisplatin (cisplatin, DDP), mitomycin C (MMC), fluorouracil (fluorouracil, 5-Fu), and others have an efficacy rate of 60% to 90%. In recent years, intraperitoneal injection of biological agents for treatment has become increasingly common, with commonly used ones including lentinan, interferon, and interleukin-2 (IL-2), with efficacy rates between 70% and 90%. The Kanglete injection is a natural effective anticancer active substance extracted from the Chinese herb Coix seed, and is a biphasic broad-spectrum multifunctional anticancer drug. It mainly blocks cells in the G2 and M phases of the cell cycle, reducing the number of cells entering G0 and G1 phases, and causing the percentage of S phase cells to decrease, inhibiting tumor growth and directly inhibiting and killing cancer cells. The Kanglete injection is an emulsion that allows for sufficient contact between the peritoneal surface and the intraperitoneal drugs, preventing the leakage of fluid, thereby achieving therapeutic effects. Most anticancer drugs have limited penetration ability, among which carboplatin has strong penetration ability (about 1-2mm), and fluorouracil (5-Fu) has a small molecular weight, strong penetration ability through tissue spaces and cell membranes, and is easy to penetrate tumor tissue.

　　Repeated administration in the abdominal cavity can stimulate the exudation, fibrosis, and adhesion of the peritoneum, thereby significantly reducing the formation of peritoneal fibrosis and adhesion, allowing the drug to spread and absorb well in the abdominal cavity, and extending the retention time of the drug in the abdominal cavity, thereby enhancing the antitumor effect.

　　(3) Administration method:

　　① Peritoneal puncture: It is the routine method for abdominal medication, which can be used to inject chemotherapy drugs or aspirate ascites, control its growth speed, and alleviate symptoms. However, repeated puncture is time-consuming and laborious, and it is easy to plant tumor cells under the skin.

　　② Peritoneal catheter placement: that is, after peritoneal puncture, a silicone tube is placed in the appropriate position in the abdominal cavity, and long-term medication is given through the silicone tube. Because the silicone tube is thin and soft, it does not stimulate the abdominal organs, does not interfere with the patient's daily activities, does not interfere with systemic treatment, and is safe and convenient to administer, with few complications and less likely to occur catheter blockage, so it has been widely used in recent years.

　　3. Combined treatment:The size of peritoneal metastatic tumor nodules is an important factor affecting peritoneal chemotherapy. Elias reported that peritoneal chemotherapy is almost ineffective for metastatic tumors with nodules larger than 3mm. Therefore, it is necessary to combine peritoneal debulking surgery with peritoneal chemotherapy. The debulking peritoneal resection should remove all visible metastatic tumor nodules in the peritoneal cavity as much as possible, providing good conditions for peritoneal cavity chemotherapy. Postoperative application of sodium hyaluronate, 5-Fu, and carboplatin complex drug solution DDS pump peritoneal chemotherapy has good clinical efficacy.

　　4. Continuous abdominal cavity hot perfusion chemotherapy:It is a new technology adopted in recent years for the prevention and treatment of abdominal malignant tumors, especially for postoperative recurrence and peritoneal metastasis of gastrointestinal cancer. It comprehensively utilizes regional chemotherapy, hyperthermia, and the mechanical lavage effect of large-volume fluid on the abdominal cavity to clear and kill free abdominal cancer cells and micro-tumors during surgery, effectively preventing and treating postoperative recurrence and metastasis, and is the most reasonable and effective auxiliary measure in combination with surgery.

　　Its indications include: malignant tumors in the abdominal cavity that involve the serosal or peritoneal layer, or those that have undergone radical surgery; especially suitable for advanced gastrointestinal malignant tumors, liver, gallbladder, pancreas malignant tumors, ovarian, uterine malignant tumors, etc.; patients with peritoneal disseminated micro-metastatic nodules, who can only palliatively resect the primary tumor in the abdominal cavity; patients with recurrence and metastasis in the abdominal cavity after surgery, combined with reoperation. However, it is contraindicated in patients with severe cardiovascular diseases and those with obvious liver and kidney dysfunction.

　　Since CHPP has been applied in clinical practice since the 1980s, it has achieved certain clinical effects. Yonemura et al. conducted a CHPP efficacy observation on 160 cases of gastric cancer randomly divided into two groups, and the 5-year survival rate of the CHPP group was higher than that of the control group, but there was no significant difference (P=0.052); however, the 5-year survival rate of the cases observed with serosal invasion was significantly higher than that of the control group; according to the stage of gastric cancer, the 5-year survival rate of the CHPP group was significantly higher than that of the control group in stage IV. Hamazoe et al. reported that the 5-year survival rate of the CHPP group was significantly higher than that of the control group in 82 cases of advanced gastric cancer with visible serosal invasion, no peritoneal dissemination, and no intra-abdominal metastasis after extensive tumor resection. For patients with peritoneal seeding metastasis or serosal invasion in cancerous ascites, extensive resection of the cancerous mass followed by CHPP, all patients underwent repeated cytological examination of the Douglas pouch, and all were negative. The ascites of patients with cancerous ascites disappeared rapidly. The 1-year survival rate of the CHPP group was 68%, while that of the control group was only 30%, and the 3-year survival rate was 39%, with zero in the control group. Some people reported that for patients with positive cancer cell examination in the pelvic lavage fluid after rectal cancer surgery, all were negative after CHPP, and there was no recurrence during the follow-up of 16.9±9.7 months.

　　The main side effects of CHPP include: bone marrow suppression, acute renal failure, intestinal adhesion, anastomotic fistula, pelvic infection, urinary retention, etc. Acute renal failure is caused by a pre-renal cause, such as peritoneal edema caused by inappropriate perfusion, which reduces renal blood flow. Bone marrow suppression quickly returns to normal about 2 weeks after CHPP. If the indications are properly mastered and the application is good, CHPP can achieve good preventive and therapeutic effects.

　　II. Prognosis

　　Although efforts have been made continuously in recent years, the survival period of abdominal metastatic tumors has been extended, and some reported results are also optimistic, but it is still a middle and late-stage tumor, and there is no report of long-term survival at present.