 Diagnosis and staging for cancer patients can be dramatically improved by supplementing standard techniques with positron emission tomography (PET) scanning, according to a study in the Jan. 1 issue of the Journal of Clinical Oncology.
In the study of 105 lung cancer patients, two-thirds had their scheduled treatment altered following PET scans. "The 67% is an amazing number," says co-author Rodney Hicks, MD, of the Peter MacCallum Cancer Institute in Melbourne. "In about a third of the patients we changed either the treatment modalities from surgery to radiotherapy or the treatment technique from, say, curative to palliative." Hicks, director of diagnostic imaging at the institute, says the other third of the patients had the size or location of their radiation therapy field altered to obtain more effective treatment.
PET is a highly specialized imaging technique using short-lived radioactive substances. The technique produces three-dimensional colored images to provide information about the body's chemistry unavailable through other procedures. Unlike computerized tomography (CT) or magnetic resonance imaging (MRI), which look at anatomy or body form, PET looks at metabolic activity or body function.
"Use of this technique is growing by the day," says Hicks, adding that the imaging technique is appropriate for many types of cancer. "We?re looking at malignant potential, or how the tumor is growing." As a result, he says, several patients in the study underwent surgery that at first was ruled out as useless. Others scheduled for radiation were spared that procedure. "In that way we are able to spare the patient the morbidity ? the sickness ? associated with a very toxic treatment using high-dose radiotherapy and give them the appropriate systemic treatment that they need for spread outside the chest," Hicks says.
CT Scans Standard Robert Smith, director of cancer screening for the American Cancer Society (ACS), says that typically a lung cancer patient in the United States would get a CT scan, although PET scans are used in certain cases. "It?s becoming more and more common," he says.
Keying in on the appropriate treatment is critical, says Smith. "The scans can help avoid treatment that may not be at all beneficial. That?s important when you?re not likely to survive the disease, and lung cancer in particular is a disease where there is usually a poor prognosis."
Smith notes that the study needs to be repeated but that any technique that improves care and provides for a more accurate diagnosis of cancer is welcome.
Useful For Various Cancers
Just as with lung cancer, PET scans could save patients with esophageal cancer from difficult surgery by revealing whether the cancer had extended into lymph nodes. PET scans would also be useful in evaluating the spread of the disease in melanoma and cancers of the mouth and throat, where lymph node removal could improve the outcome.
According to Anthony Ciarolla, MD, of Oncology Hematology Medical Group in Long Beach, California, PET scans are also useful for staging lymphomas "and are taking the place of gallium scans, another radioactive scan. Another area that these scans have proved valuable is in patients who have had colorectal cancer recur in their liver. The PET scan can tell if that is the only site of recurrence and whether these patients would benefit from surgery."
Scans Are Cost-Effective: Even Medicare Agrees Hicks agrees that more studies on the efficacy of PET scans need to be conducted. But he says there is already evidence they pay for themselves, even though some health care providers still balk at paying for them."The cost-effectiveness of PET has been looked at in a number of groups and it?s been suggested that sparing unnecessary, aggressive treatments will offset the cost of PET scanning," says Hicks, "I think people will become more aware of PET scanning in the very near future." Doctors have also begun to use the PET scan for diagnosis in patients with heart disease and Alzheimer?s disease. The cost for the test is estimated at around $2,000.
A spokesperson for Medicare announced in mid-December that the program will begin paying for PET scans to help in the diagnosis of melanoma, lymphoma, and cancers of the lung, esophagus, colon, rectum, mouth and throat. The decision will take effect some time before July of 2001.
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