Conformal Radiation Therapy Safe in individuals with Inoperable Liver Cancer
A new approach to radiation therapy, called 3D conformal radiation therapy, may be effective and safer than the standard radiation therapy methods for persons with inoperable liver cancer. Researchers from Taiwan recently reported that 3D conformal radiation therapy appears to kill cancer cells while reducing the number of healthy liver cells that are exposed to the radiation.
Primary cancer of the liver is characterized by cancer cells that begin to grow in the liver, the largest organ in the human body. These cancer cells can then grow in size and can also spread to the veins or arteries of the liver and/or to other parts of the body (calledadvanced or metastatic disease). The most common type of primary liver cancer is called hepatocellular carcinoma. Hepatocellular carcinoma often develops in persons whose livers are damaged by other serious conditions, such as hepatitis and/or cirrhosis.
The treatment of hepatocellular carcinoma depends on many factors including the size and stage of the cancer (extent of disease at diagnosis) and the overall health of the patient. When possible, the cancer is completely surgically removed from the liver (called surgical resection), offering a chance for cure. However, when the cancer is too advanced or large to be removed by surgery or the patient is too ill to undergo surgery, effective nonsurgical treatments are needed to control the cancer and prolong survival time. Several options may be used for this purpose.
One technique that has recently been used to treat inoperable liver cancers, called chemoembolization, involves blocking the main artery that supplies the liver (called the hepatic artery) and injecting chemotherapy drugs between this blockage and the liver. This method of delivery allows the drugs to travel to the cancer cells in the liver, while also blocking much of the blood supply to the cancer cells. This approach is effective because cancer cells in the liver receive much of their blood supply from the hepatic artery while healthy liver cells also receive blood from what is called the portal vein.
Another treatment option, radiation therapy, has in the past been limited in the treatment of liver cancer because it can cause damage to healthy as well as cancerous liver cells. Persons whose liver is damaged by cancer and by hepatitis and/or cirrhosis often cannot tolerate further damage by radiation therapy. For this reason, researchers have developed a new approach to radiation therapy, called 3D conformal radiation therapy, to allow more radiation to be aimed directly at the cancer cells and more healthy cells to be spared this exposure.
Researchers in Taiwan treated 13 persons with hepatocellular carcinoma, 9 of whom had extensive disease that included the main vein supplying the liver (called the portal vein), other veins near the liver, jaundice, or disease that was previously treated with chemoembolization. These 9 patients received 3D conformal radiation therapy, while the remaining 4 patients underwent both 3D conformal radiation therapy and chemoembolization. Overall, 58% of the patients had a partial response and another 25% had a minimal response to the treatment. In the group receiving the combination therapy, all patients lived for more than 1 year. In the group receiving radiation therapy only, 1 patient with involvement of the portal vein was able to undergo surgery to remove the cancer after the treatment. Fifteen months after the therapy, this patient is alive and has had no recurrence (return) of the cancer. The new 3D conformal radiation therapy approach indeed appeared to be safer than more conventional radiation therapy, although 1 person did develop liver failure 1 month after completing the therapy.
From these findings, the researchers concluded that hepatocellular carcinoma appears to be vulnerable to radiation therapy and that the 3D conformal radiation therapy approach helps to reduce the exposure of healthy liver cells to the radiation. These preliminary results suggest that 3D conformal radiation therapy may offer a safer treatment option for persons with inoperable liver cancer and indicate that further study of this approach is needed. Persons who have hepatocellular carcinoma may wish to talk with their doctor about the risks and benefits of participating in a clinical trial in which 3D conformal radiation therapy or another promising new therapy is being studied.
(Journal of Gastrenterology and Hepatology, Vol 10, No 10, pp 1025-1033, 1999)