Feb. 1, 2011 -- A new test appears to predict whether or not cancer will spread to other parts of the body.
The test is a long way from doctors' offices. But in early studies, it has about a 90% success rate in predicting whether a cancer will spread within two years.
The new test is based on an errant protein found in cancers that metastasize -- that is, send out tumor cells that travel to distant parts of the body where they grow into new tumors. The protein is called CPE-deltaN, says senior investigator Y. Peng Loh, PhD.
"By measuring CPE-deltaN or its RNA in a tumor, we can tell two things: whether the tumor already has spread, and whether the tumor is likely to recur or spread," Loh said at a news teleconference held to announce the findings.
Predicting Cancer Spread
A tumor is bad enough in the place where it starts. But cancers that stay in one place often can be surgically removed (resected), usually with a high cure rate.
Metastatic cancer is another story. In a process still not fully understood, tumor cells leave the original (primary) tumor and spread to other places in the body. The tumor cells may fight their way through body tissues into the bloodstream or lymphatic system. These metastases may spread cancer to several sites in the body.
Doctors can't tell which cancers will spread and which will not. It's often not even possible to tell what stage of cancer a person has until the primary tumor is resected and examined.
The current test, if validated in large numbers of patients with different kinds of cancer, could change that, says study researcher Steven Hewitt, MD, PhD, of the National Cancer Institute's Advanced Technology Center.
"We were able to beat the current standard of care for determining the stage and grade of cancers," Hewitt said at the news conference. "Tests such as this, which we can perform on a small tumor sample without full resection, allows doctors to better plan patient care."
The test won't tell doctors which treatment would work best. But in clinical studies of patients with liver cancer, the new test predicted cancer spread in patients with early stage II tumors and predicted that cancer would not spread within two to three years in patients with later stage III and stage IV tumors.
Lei Xu, PhD, a cancer researcher at the University of Rochester in New York, noted that the Loh team is still a long way from proving it has a test that doctors can use. But she said the thoroughness of the study is impressive and that the test shows great promise. Xu was not involved in the Loh study.
"Absolutely this test would be useful. Prediction of metastases is virtually impossible for most tumor types," Xu tells WebMD. "You don't know when metastasis starts. It can take decades. So if you had this kind of marker, you could know early on and do preventive clinical work to stop that from happening."
The finding that CPE-deltaN is crucial to cancer spread has another implication. If the protein or the broken gene that makes it could be neutralized, cancers might not spread. Indeed, when lab animals were implanted with tumors in which CPE-deltaN RNA had been blocked, the tumors did not spread.
Loh and colleagues at the National Institutes of Health and the University of Hong Kong report their findings in the Feb. 1 online issue of the Journal of Clinical Investigation.