Researchers have found that a unique pattern of activity for genes in cells located in the tissue surrounding a liver tumor can accurately predict whether the cancer will spread to other parts of the liver or to other parts of the body. This preliminary research was led by a team of researchers*, including several from the National Cancer Institute (NCI), part of the National Institutes of Health (NIH), and other institutes, who report these findings in the August 2006 issue of Cancer Cell **.
“Research into the role of inflammation in hepatocellular carcinoma, a type of liver cancer, is very important because inflammation is one of the first lines of defense mobilized by the immune system in response to tissue injury or infection. A better understanding of the inflammatory process will hopefully lead to better treatments for this deadly disease,” said NIH Director Elias A. Zerhouni, M.D.
“Persistent and extensive inflammation of the liver is a common problem in hepatocellular carcinoma, or HCC, patients,” said Xin Wei Wang, Ph.D., head, Liver Carcinogenesis Unit at NCI’s Center for Cancer Research and study leader. “We wanted to examine the role that the large number of immune cells in the liver may play in supporting spread of the tumor.”
“The tendency of hepatocellular carcinoma tumors to metastasize or recur following surgery contributes to the poor outcome associated with this disease,” said NCI Acting Director John E. Niederhuber, M.D. “Accurately predicting this cancer’s risk of spread will help doctors decide on the best options to use in treating patients.”
Researchers analyzed gene expression signatures — patterns of gene activity — largely in immune cells within the liver microenvironment, which is the area immediately surrounding the tumor. The set of 17 genes included those that encode the messages for cytokines, which are small proteins produced by immune cells that are used to communicate messages between cells in the immune system to either turn up or down the immune response.
From the 17-gene set, researchers identified a unique pattern in the immune cells found in normal tissue of the liver microenvironment that could predict the potential for liver tumor metastasis. This metastasis-specific profile included gene activities responsible for increased production of certain cytokines that are associated with an anti-inflammatory response, as well as suppression of immune response. Increased levels of these cytokines are associated with a poor prognosis of cancer.
“When we used the gene signature of immune cells in the liver, we could predict tumors that would metastasize in 92 percent of the samples we studied,” said Wang. “This is the first example where we can stratify HCC patients to identify those who would benefit from certain post-surgical treatments to prevent metastases and recurrence.”
The 115 HCC patients included in the study were being treated at the Zhongsham Hospital, Shanghai, China. Fifty-two patients had tumors that had metastasized within the liver or to other organs, and 63 had tumors that had not metastasized. Samples from 22 patients with chronic liver disease and from eight normal livers were also studied as controls.
“We previously identified gene signatures in the liver tumor that could accurately predict the tumors that were capable of metastasis in 78 percent of the cases we studied,” explained Wang. “This study is different because the immune cells associated with this signature are in the patient’s normal liver tissue — the microenvironment of the tumor. With this microenvironment gene signature, we could predict metastatic disease in 92 percent of the samples.”
HCC is the most common liver cancer diagnosed in adults and has a high prevalence in Asian and African populations. The rate of new HCC cases has been rising over the past 10 years in the United States. HCC is a very aggressive disease; patients usually survive less than one year after diagnosis. HCC occurs twice as often in men as in women. In 2006, an estimated 18,500 Americans will be newly diagnosed with liver cancer and an estimated 16,200 will die of the disease.
For more information on Dr. Wang’s research, go to http://ccr.cancer.gov/staff/staff.asp?profileid=5764.
