Most forms of cancer still must be spotted visually to be diagnosed. But if a newly devised virus can do the job, it could track down cancer cells too small or well hidden to be seen in scans. It might also help shrink tumors, too.

The virus in question is a herpes virus, modified genetically to act only on cancer cells.

Using mice, researchers injected the altered virus, which then "deliver[s] genetic information that induces a known blood biomarker for cancer to be secreted by cancer cells," Timothy Cripe, a physician in the Division of Oncology at Cincinnati Children's Hospital Medical Center and co-author of a new paper outlining the technique, said in a prepared statement.

The biomarker, Gaussia luciferase, is easy for researchers to spot via urine or blood tests. The virus might also help to diminish any existing tumors, the study authors reported, making it a so-called theragnostic compound. Altered versions of smallpox and herpes viruses are already in clinical trials to help battle back cancer. 

The virus made cancer cells produce detectable levels of the biomarker in 90 percent of subject mice with bone cancer, muscle cancer, Ewing's sarcoma and other forms of malignant tumors. It even raised glowing flags in mice that had microscopic amounts of cancer cells hiding in their kidneys, suggesting that in humans it might work to root out tumors that are just millimeters across.

The researchers do raise concerns about possible immune responses to the virus, and even cancer-free mice showed low levels of the biomarker. Cripe noted that "there is certainly room for further refinement." But, he added, "If ultimately validated in human trials, it could have implications for people with known cancer risk or who have had a history of cancer." It could also be used to help track the progress of treatment.

Except for the few types of cancer for which there are already known biomarkers, such as prostate and some liver cancers, broader cancer screening has been hampered by high costs and limited access to sophisticated equipment. But given the viral injection method's simplicity, it could help make cancer screening more universal.

It could also prove especially helpful in improving cancer diagnosis in areas that lack advanced imaging equipment, such as remote or developing regions. And that could help stem the costs of cancer care, which are expected to rise to exceed $157 billion—and be as high as $207 billion—in the U.S. alone by 2020, by reducing the rates of expensive established cancers that escape early-stage diagnosis.

"Early cancer detection is vital to improve cure rates," Cripe said. "Cancer stage predicts prognosis."

The study was published online May 11 in PLoS ONE.

Image courtesy of iStockphoto/Henrik5000