Doctors in a new study claim a more sensitive indicator of liver cancer may exist that could help physicians diagnose the disease earlier.1
A More Sensitive Cancer Indicator
The indicator, known as a biomarker, is known as an immune complex, a combination of an antigen and antibody that tends to accumulate in body tissue and is linked with various diseases. (Antigens are molecules on the surfaces of cells or viruses capable of stimulating an immune response. Antibodies (also known as immunoglobulin) are proteins that help make up the immune system, and fight off infection.)
The name of the biomarker is squamous cell carcinoma antigen (SCCA)-immunoglobulin M (IgM), and may be helpful to detect liver cancer because of the relatively reduced ability of current biomarkers to detect this type of cancer, wrote Giorgio Fassina, PhD, of Xeptagen S.p.A. Life Biotechnology in Pozzuoli, Italy and his colleagues.
'Adequate Screening Programs' Are Needed
The many various causes "for the vast majority of hepatocellular carcinomas (HCCs), such as hepatitis B virus, hepatitis C virus, alcohol abuse, and the poor prognosis for patients with primary HCC, require the development of adequate screening programs for patients at risk, including chronic carriers of HBV and HCV," Fassina and his fellow researchers wrote.
Alpha-fetoprotein (AFP), a protein substance normally produced by liver cells, is widely used as an indicator of such cancer because it is found at higher levels in the blood in up to 60 percent of liver cancer patients. Still, it also isn't very specific for cancer because "a considerable number of patients with chronic liver disease" also have high levels of AFP, the researchers pointed out.
They zeroed in on the combination of SCCA and IgM because previous studies found this marker in all liver cancer specimens, but in none of normal livers tested.2
Scrutinizing Blood Samples
Fassina and his colleagues decided to determine how sensitive (and how specific to liver cancer) SCCA-IgM was compared to AFP. They collected blood samples from 160 patients with various forms of liver disease (including 60 with liver cancer) and compared the results to those of 73 healthy people without liver disease. The large majority of those with liver cancer had contracted the disease from hepatitis C infection.
Blood samples were also collected from a group of 50 people with confirmed cirrhosis.
Tests were then conducted on each sample to look for evidence of either SCCA-IgM or alpha-fetoprotein. Simultaneously, liver biopsies were performed on 22 people with chronic hepatitis, in 46 with liver cirrhosis, and in 40 people with liver cancer.
Fassina's group found that 35 of 50 blood samples (70%) taken from those with hepatocellular carcinoma showed high levels of SCCA-IgM, whereas all the blood samples from the group of healthy people showed no levels of this marker.
There was no link between levels of the marker and the cause of liver cancer. In those with cirrhosis, the marker was detectable in about one-quarter of the blood samples. In those with chronic hepatitis C, the biomarker was detectable in 18% of the samples.
By comparison, only 21 of 50 patients (42 percent) had elevated levels of alpha-fetoprotein as an indicator of liver cancer. While not all blood samples from liver cancer patients showed levels of SCCA-IgM, there were more samples that did compared to samples that levels of AFP.
A Combination That Offers More Accuracy
In conclusion, the researchers wrote: "The detection of both AFP and SCCA-IgM significantly improved the ability to discriminate hepatocellular carcinoma from cirrhosis and chronic hepatitis."
However, the investigators found that SCCA-IgM levels were more accurate as a marker for liver cancer than those of AFP. "A similar improvement was observed in differentiating hepatocellular carcinoma from chronic hepatitis, in which SCCA-IgM showed higher accuracy than AFP," they wrote.
SCCA-IgM was also very accurate at distinguishing liver cancer from cirrhosis, they noted. Levels of both markers can increase the accuracy of diagnosing liver cancer even higher, the study team added.
1. Beneduce L, Castaldi F, Marino M et al. Squamous cell carcinoma antigen-immunoglobulin M complexes as novel biomarkers for hepatocellular carcinoma. Cancer 2005 Jun 15;103(12):2558-65.
2. Pontisso P, Calabrese F, Benvegnu L et al. Overexpression of squamous cell carcinoma antigen variants in hepatocellular carcinoma. Br J Cancer 2004 Dec 13;91(12):2103.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
