09/04/2001 - Updated 02:19 PM ET

By Robert Davis, USA TODAY

Doctors who see PET scan images of their breast cancer patients often change the course of treatment after getting the clearer picture, says a survey out today.

The survey, which appears in today's Journal of Nuclear Medicine, found that when breast cancer patients underwent a PET scan, they learned more about how their cancer was growing inside them. The finding is significant because not all cancer patients get PET scans. Positron emission tomograpy — which a decade ago was limited primarily to teaching hospitals — is just now emerging as the standard of care. Medicare is considering covering PET scans for recurrent breast cancer patients.

"Once you've worked with PET, you don't want to get into an environment where you don't have it," says Johannes Czernin, a UCLA doctor and study author. PET scans measure the way cells burn sugar. Cancer cells gobble up lots of sugar. The scan spots this higher metabolic activity by using radioactive tracers that are injected into the bloodstream. The tracers concentrate in the parts of the body that are using more sugar, and that makes a dark spot appear on the PET scan.

The survey found that a PET scan led to a change in the course of treatment for 60% of women.

Often, 36% of the time, this change resulted because of a dramatic finding that the cancer was either as bad or much worse than previous tests had indicated.

For example, one 73-year-old woman who had previously had her right breast removed to rid her body of cancer was found with a PET scan to have cancer in her liver. Instead of chemotherapy alone, she had more surgery to remove the cancer from her liver.

Carole Edelstein, 58, a psychiatrist who teaches at UCLA, where the survey was conducted, says her doctors were able to pinpoint a tumor in her breast on the eve of her mastectomy.

"It gave me my left breast, which was scheduled for the garbage can," she says.

More traditional scans — mammography, ultrasound and MRI — had not found the cancer growing in her breast. But a lump under her arm told doctors that cancer was there.

But just before they were scheduled to remove the breast, the PET scan found the tumor; surgeons were able to extract it during a less invasive lumpectomy.

"It was that simple," Edelstein says. "It totally changed in two days what I had to have done and what I had to live with."