The CyberKnife System delivers high doses of radiation directly to liver tumors. The CyberKnife System offers patients who cannot undergo liver cancer surgery due to their poor medical condition, or who refuse surgery, a minimally invasive alternative treatment for liver cancer.
CyberKnife liver cancer treatments are typically performed on an outpatient basis with one to five treatments, requiring no overnight hospital stays. Most patients experience minimal to no side effects with a quick recovery time.
Liver cancer is the abnormal growth of cells in the liver resulting in a liver tumor. If the abnormal cells originated as liver cells, the resulting collection of cells is called a primary liver tumor. Some liver tumors are benign, meaning they are not cancerous and do not spread to other parts of the body. Malignant liver tumors, however, can invade other organs, and spread throughout the body. Most primary malignant liver cancers are classified as hepatocellular carcinoma or called hepatomas.
A much more common cancer of the liver is a metastatic liver tumor. In this case, cancerous cells from another part of the body are carried to the liver by the blood or other bodily fluids. Metastatic liver tumors can spread to the liver from the colon, lung, breast, stomach and pancreas, as well as other sites in the body.
More than 21,300 cases of primary liver cancer are expected to be diagnosed in the United States in 2008. Primary liver cancer is expected to result in approximately 18,410 deaths during that time. Five-year relative survival rates for metastatic cancer to the liver is 3.3 percent.
After liver cancer has been detected and staged, the doctor will discuss different treatment options. Treatments for liver cancer depend on the type of cancer and the stage. Early-stage primary liver cancer, and some metastatic tumors, may be treated with surgery, with the goal of removing the entire tumor. Alternatively, the tumor may be treated by ablation – or destroying it in place – using one of several methods, including the application of a high-temperature probe (radiofrequency ablation), a low-temperature probe (cryoablation), focused chemotherapy treatment (chemoembolization), conventional radiation therapy, local alcohol injection or CyberKnife Radiosurgery. In some cases, the entire liver can be removed and replaced with a donor liver transplant. With more advanced cases of liver cancer, chemotherapy combined with some of the above mentioned treatments may be used.
Radiosurgery devices, such as the CyberKnife Robotic Radiosurgery System, offer patients a new option for liver cancer treatment. The CyberKnife System can deliver high doses of radiation with extreme accuracy because of its ability to track the location liver tumors in real-time during treatment. The CyberKnife System uses the Synchrony® Respiratory Tracking System to track tumor motion as patients breathe normally, and adjusts the radiation beam accordingly. The Synchrony System correlates the rise and fall of the chest with the actual location of the tumor in X-ray images. As a result, during CyberKnife treatment, patients can lie comfortably and breathe normally without any frames, and are not asked to hold their breath or perform any complex breathing maneuvers. The Synchrony System can track moving targets with an accuracy of 1 millimeter or better, which allows clinicians to deliver radiation precisely to the tumor and limit exposure to healthy surrounding tissue.
Surgery is the common procedure for treating liver tumors that are localized and have not spread widely throughout the liver. This type of surgery, often called a partial hepatectomy, involves the surgeon making a large incision in the abdomen and cutting away a section of liver containing the tumor and some of the surrounding healthy tissue. Liver cancer surgery generally is feasible when the disease is limited. Under such conditions, resection of a primary liver tumor can lead to a five-year survival rate of 60 percent to 75 percent, and resection of a metastatic tumor may result in five-year survival rates of 25 percent to 39 percent. Unfortunately, only 20 percent to 30 percent of patients with liver cancer are eligible for surgery because their disease is too advanced and/or their liver functions are extremely poor. Liver cancer surgery may pose significant risk of complications, such as infection, bleeding, respiratory and cardiac problems. Approximately 2 percent to 6 percent of patients have died as a result of liver cancer surgery.
Surgery may be the only treatment necessary or it may be combined with chemotherapy or radiation for patients with widespread cancer or an advanced stage of their primary tumor.
Conventional radiation therapy, called external beam radiation therapy, typically involves delivery of radiation that encompass both the tumor and a certain amount of surrounding healthy tissue. These radiation fields delivered in small doses over many sessions in the course of several weeks are necessary to account for the tumor’s movement as the patient breathes. These radiation fields limit the total radiation dose that can be given in each treatment session because of the normal liver tissue included in the radiation fields, making it necessary to divide up the total treatment in 20 to 30 sessions given over weeks.
Chemotherapy is used when cancer cells are thought to be located throughout the body or they are present in a patient’s blood or other fluids, which is often the case with metastatic tumors and advanced-stage liver cancer. Chemotherapy medication is delivered orally or through an IV, and is given to a patient either as the sole treatment or in combination with other types of liver cancer treatment. Chemotherapy affects both normal tissue and the cancer cells, so patients may experience side effects, such as severe nausea and vomiting, infections, fatigue and weight loss. Chemotherapy has not provided clinical benefit or prolonged survival for patients with advanced primary liver cancer and randomized trials have not shown any benefit of neoadjuvant therapy, a treatment that's given first to help make the next treatment step go more smoothly, or adjuvant systemictherapy, which is a type of treatment given after surgery to target the entire body in hopes of destroying any cancer cells that may have traveled to distant body parts, but are below the level of clinical detection. HCC remains a highly lethal disease that is resistant to traditional cytotoxic chemotherapy. The last 30 years of chemotherapy clinical trials for advanced HCC have repeatedly failed to demonstrate any survival benefit for a long list of drugs. However a survival advantage was recently established for sorafenib, instituting a new standard of care for inoperable HCC.
Recent advancement for our Interventional Radiology (IR) section, in collaboration with the Radiation Oncology department, is the use of radioembolization to treat patients with unresectable liver cancer. Often referred to as “mircospheres,” these resin-based beads (a beta radiating isotope) are injected into the hepatic artery via a catheter by an interventional radiologist. The microspheres lodge in the tumor and the radiation will lead to damage of tumor tissue and, in the best case, to a complete elimination of the tumor.