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A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates.
Liver tumors are abnormal growth of liver cells on or in the liver. Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. Liver tumors can be classified as benign (non-cancerous) or malignant (cancerous) growths. They may be discovered on medical imaging, and the diagnosis is often confirmed with liver biopsy. Signs and symptoms of liver masses vary from being asymptomatic to patients presenting with an abdominal mass, hepatomegaly, abdominal pain, jaundice, or some other liver dysfunction. Treatment varies and is highly specific to the type of liver tumor.
Interventional radiology (IR) is a medical subspecialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs both diagnostic and therapeutic procedures through very small incisions or body orifices. Diagnostic IR procedures are those intended to help make a diagnosis or guide further medical treatment, and include image-guided biopsy of a tumor or injection of an imaging contrast agent into a hollow structure, such as a blood vessel or a duct. By contrast, therapeutic IR procedures provide direct treatment—they include catheter-based medicine delivery, medical device placement, and angioplasty of narrowed structures.
Transcatheter arterial chemoembolization (TACE) is a minimally invasive procedure performed in interventional radiology to restrict a tumor's blood supply. Small embolic particles coated with chemotherapeutic drugs are injected selectively through a catheter into an artery directly supplying the tumor. These particles both block the blood supply and induce cytotoxicity, attacking the tumor in several ways.
In the fetus, the ductus venosus shunts a portion of umbilical vein blood flow directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. Compared to the 50% shunting of umbilical blood through the ductus venosus found in animal experiments, the degree of shunting in the human fetus under physiological conditions is considerably less, 30% at 20 weeks, which decreases to 18% at 32 weeks, suggesting a higher priority of the fetal liver than previously realized. In conjunction with the other fetal shunts, the foramen ovale and ductus arteriosus, it plays a critical role in preferentially shunting oxygenated blood to the fetal brain. It is a part of fetal circulation.
Transjugular intrahepatic portosystemic shunt is an artificial channel within the liver that establishes communication between the inflow portal vein and the outflow hepatic vein. It is used to treat portal hypertension which frequently leads to intestinal bleeding, life-threatening esophageal bleeding and the buildup of fluid within the abdomen (ascites).
In human anatomy, the hepatic portal system is the system of veins comprising the hepatic portal vein and its tributaries. It is also called the portal venous system and splanchnic veins, which is not synonymous with hepatic portal system and is imprecise.
Defibrotide, sold under the brandname Defitelio, is a mixture of single-stranded oligonucleotides that is purified from the intestinal mucosa of pigs. It is used to treat veno-occlusive disease of the liver of people having had a bone marrow transplant, with different limitations in the US and the European Union. It works by protecting the cells lining blood vessels in the liver and preventing blood clotting; the way it does this is not well understood.
Percutaneous hepatic perfusion (PHP) is a regionalized, minimally-invasive approach to cancer treatment currently undergoing Phase II and Phase III clinical testing. PHP treats a variety of hepatic tumors by isolating the liver and exposing the organ to high-dose chemotherapy. As demonstrated in clinical trials, patients treated by PHP can tolerate much higher doses of chemotherapeutic agents than those receiving traditional systemic chemotherapy without increased toxicities.
Delcath Systems, Inc. is a publicly traded specialty pharmaceutical and medical device company that develops percutaneous perfusion technologies for the targeted administration of high-dose chemotherapeutic agents to specific organs or regions of the body. Based in Queensbury, New York, the company has an intellectual property portfolio consisting of 28 patents worldwide. Delcath's Percutaneous Hepatic Perfusion (PHP) is currently undergoing Phase II and Phase III trials against tumors in the liver. Delcath has a Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute and has received Fast Track and a Special Protocol Assessment from the Food and Drug Administration for its use of melphalan in treating unresectable liver tumors. PHP, also known as the Delcath System, is tested for the treatment of metastatic melanoma in the liver and for primary liver cancer and metastatic hepatic malignancies from neuroendocrine cancers and adenocarcinomas, as well as patients with melanoma who previously received isolated perfusion. Chemotherapy is usually delivered intravenously, although a number of agents can be administered orally.
TheraSphere is a radiotherapy treatment for hepatocellular carcinoma (HCC) that consists of millions of microscopic, radioactive glass microspheres being infused into the arteries that feed liver tumors. These microspheres then embolize, lodging themselves in the liver's capillaries and bathing the malignancy in high levels of yttrium-90 radiation. It is currently approved as a Humanitarian Device, meaning effectiveness has not been proven, for patients as a neoadjuvant to surgery or transplantation by the U.S. Food and Drug Administration and is being used at a number of clinical centers in the United States.
Gliosarcoma is a rare type of glioma, a cancer of the brain that comes from glial, or supportive, brain cells, as opposed to the neural brain cells. Gliosarcoma is a malignant cancer, and is defined as a glioblastoma consisting of gliomatous and sarcomatous components.
Hepatic Arterial Infusion (HAI) is a medical procedure that delivers chemotherapy directly to the liver. The procedure, mostly used in combination with systemic chemotherapy, plays a role in the treatment of liver metastases in patients with colorectal cancer (CRC). Although surgical resection remains the standard of care for these liver metastases, majority of patients have lesions that are unresectable. The liver derives its blood supply from two sources – via the hepatic arterial circulation and the portal circulation. Liver metastases get most of their blood supply primarily from the hepatic artery, whereas the normal liver cells get their blood supply from the portal circulation. This allows for chemotherapeutic drugs to be delivered directly to the cancer cells if infused into the hepatic artery. Multiple trials have compared HAI to systemic chemotherapy. Compared to systemic Fluoropyrimidine, HAI with Floxuridine (FUDR) had an increased response, but there was no overall increase in patient survival. Efforts have been made to increase the efficacy and safety of HAI chemotherapy: when a combination of FUDR and dexamethasone was used for HAI, both response rate and median survival increased. In another study, a combination of FUDR and leucovorin for HAI increased the response rate, and reduced the biliary toxicity seen with the use of FUDR alone. Considering improvements in the surgical placement of the HAI pump and studies showing promising results when HAI therapy is used together with systemic oxaliplatin or irinotecan, there is once again an increased interest in the role of HAI as a treatment option in patients with cancer, who have unresectable CRC liver metastases. However, studies recommend that this treatment modality be restricted to centers with expertise in the surgical placement of these pumps, and the technical aspects of localized chemotherapy.
Hyperthermia therapy(or hyperthermia, or thermotherapy) is a type of medical treatment in which body tissue is exposed to temperatures in the region of 40–45 °C (104–113 °F). Hyperthermia is usually applied as an adjuvant to radiotherapy or chemotherapy, to which it works as a sensitizer, in an effort to treat cancer.
Limb perfusion is a medical technique that is used to deliver drugs locally directly to a site of interest. It is commonly used in human medicine for administration of anticancer drugs directly to an arm or leg. It is also used in veterinary medicine to deliver drugs to a site of infection or injury, as well as for the treatment of cancer in dogs. In both cases, a tourniquet is used to reduce blood flow out of the area that is being treated.
Isolated lung perfusion is a surgical procedure during which the circulation of blood to the lungs is separated from the circulation of blood through the rest of the body, and a drug is delivered directly into the lung circulation. This allows a higher concentration of chemotherapy to reach tumors in the lungs.
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it is located in the right upper quadrant of the abdomen, below the diaphragm. Its other roles in metabolism include the regulation of glycogen storage, decomposition of red blood cells, and the production of hormones.
Selective internal radiation therapy (SIRT), also known as transarterial radioembolization (TARE), radioembolization or intra-arterial microbrachytherapy is a form of radiation therapy used in interventional radiology to treat cancer. It is generally for selected patients with surgically unresectable cancers, especially hepatocellular carcinoma or metastasis to the liver. The treatment involves injecting tiny microspheres of radioactive material into the arteries that supply the tumor, where the spheres lodge in the small vessels of the tumor. Because this treatment combines radiotherapy with embolization, it is also called radioembolization. The chemotherapeutic analogue is called chemoembolization, of which transcatheter arterial chemoembolization (TACE) is the usual form.
Hepatic artery embolization, also known as trans-arterial embolization (TAE), is one of the several therapeutic methods to treat primary liver tumors or metastases to the liver. The embolization therapy can reduce the size of the tumor, and decrease the tumor's impact such its hormone production, effectively decreasing symptoms. The treatment was initially developed in the early 1970s. The several types of hepatic artery treatments are based on the observation that tumor cells get nearly all their nutrients from the hepatic artery, while the normal cells of the liver get about 70-80 percent of their nutrients and 50% their oxygen supply from the portal vein, and thus can survive with the hepatic artery effectively blocked. In practice, hepatic artery embolization occludes the blood flow to the tumors, achieving significant tumor shrinkage in over 80% of people. Shrinkage rates vary.
Transarterial bland embolization is a catheter-based tumor treatment of the liver. In this procedure, a variety of embolizing agents can be delivered through the tumor’s feeding artery in order to completely occlude the tumor’s blood supply. The anti-tumor effects are solely based on tumor ischemia and infarction of tumor tissue, as no chemotherapeutic agents are administered. The rationale for the use of bland embolization for hepatocellular carcinoma(HCC) and/or other hyper-vascular tumors is based on the fact that normal liver receives a dual blood supply from the hepatic artery (25%) and the portal vein (75%). As the tumor grows, it becomes increasingly dependent on the hepatic artery for blood supply. Once a tumor nodule reaches a diameter of 2 cm or more, most of the blood supply is derived from the hepatic artery. Therefore, bland embolization and transarterial chemoembolization (TACE) consist of the selective angiographic occlusion of the tumor arterial blood supply with a variety of embolizing agents, with or without the precedence of local chemotherapy infusion. The occlusion by embolic particles results in tumor hypoxia and necrosis, without affecting the normal hepatic parenchyma.
References
- Isolated hepatic perfusion entry in the public domain NCI Dictionary of Cancer Terms
This article incorporates public domain material from the U.S. National Cancer Institute document: "Dictionary of Cancer Terms".
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