BOSTON -- Massachusetts General Hospital announced Wednesday what could be the beginnings of a breakthrough in diagnosing cancer.

NewsCenter 5's Liz Brunner reported that surgical biopsies, which can be painful and difficult, could one day be replaced by a simple blood test.

VIDEO: Blood Test May Replace Surgical Biopsies

Every year millions of Americans undergo sometimes painful and difficult biopsies to find out if they have cancer.

A machine could change that. Instead of surgically removing tissue, the CTC Scanner needs only a few drops of blood.

"This really works on about a teaspoon of blood," said Dr. Daniel Haber, of the Massachusetts General Hospital Cancer Center.

In small clinical trials on people with lung cancer, the CTC Scanner was more than 90 percent effective.

"We can pick up very, very rare cancer cells that normally would originate in the lung or in the breast or in other types of tissues, and we can measure them in the blood," Haber said.

Doctors can keep testing during treatment to be sure it's working.

"What we are learning now is that cancers are not always static. They can evolve. Their genetic composition can change. Their response to particular therapies can change, so it's very important to know what you are doing and what you are treating at the time that you are treating it," Haber said.

Haber and his colleagues hope to have an updated machine that can process blood samples faster within a year. FDA approval is likely years off.

"The best case scenario is that we can push the detection so that we pick up cancers earlier and earlier," Haber said.