Scans Might Better Cancer Diagnosis


Thursday, July 27th 2000, 12:00 am
By: News On 6


Doctors can much more accurately judge whether patients with lung cancer should undergo surgery if they combine two scanning techniques to find how far the malignancy has spread, a new study found.

Dutch researchers found that adding PET scans to the standard CT scans changed their decisions about the need for surgery in nearly two-thirds of patients studied. Using both kinds of scans could eliminate needless surgeries and save money.

``The main thing is patients would get the right treatment, so they would have less side effects and complications,'' said Dr. Daniel Sullivan, associate director of the National Cancer Institute's biomedical imaging program.

PET — positron emission tomography — uses a radioactive tracer to detect ``hot spots'' of increased metabolic activity typical of even tiny tumors. CT — computed tomography or ``CAT scans'' — use computerized analysis of X-rays to spot possible tumors of at least 1 centimeter.

Primarily caused by smoking, lung cancer is the most common, most deadly cancer, with a five-year survival rate of only 18 percent if it has spread to nearby parts of the chest and only 2 percent if it has spread farther.

Surgery is the best treatment if the cancer hasn't spread far. Patients who won't benefit from surgery get radiation and/or chemotherapy.

That means doctors trying to pick the best treatment must ``stage'' the cancer, determining whether surgery is likely to remove all tumors, as in the earlier stages, or whether an operation is unlikely to help, as in the later stages.

``We haven't had noninvasive techniques to accurately determine who should go to surgery and who shouldn't,'' said Dr. Edward Patz, professor of radiology at Duke University Medical School, who was not involved in the new research. ``This gives us more accurate information.''

The research appears in Thursday's edition of the New England Journal of Medicine.

The researchers studied 102 patients with ``non-small-cell lung cancer,'' which account for three-fourths of lung cancer cases. Small-cell lung cancer usually is inoperable.

Researchers at the Netherlands' Groningen University Hospital found PET scans correctly spotted 91 percent of the tumors that had spread from the lungs to the center of the chest, compared with 75 percent for the CT scans.

PET scans correctly determined cancer hadn't spread to the central chest in 86 percent, compared with 66 percent for CT scans. In 11 patients, PET spotted distant tumors that CT scans missed.

PET scans of 62 patients indicated their cancer was at a different stage than conventional scans showed. For 20 patients, finding a lower stage meant they were offered surgery instead of just drugs or radiation; for 42, the higher stage meant surgeons spared them a risky operation that wouldn't help.

While several studies in the 1990s similarly found PET scans superior to CT scans, many only looked at chest tumors. This study also scanned for tumors elsewhere, finding PET scans detected 95 percent of all tumors.

In addition, unlike most previous research, this study confirmed scan findings either by dissecting tissue removed during cancer surgery or doing a biopsy of suspected tumors in patients with inoperable cancer.

PET scan technology was developed in the 1970s, but its complexity limited its use to large research universities until recently, when insurers began covering the scans and major hospitals started buying the machines.

A 1996 UCLA study estimated using both PET and CT would save $1,154 to $2,267 per patient.

``Insurance companies pay for this stuff now because they realize if we can do a PET scan for $2,000 and save a surgery that costs $35,000, they're money ahead,'' said Dr. John Hoffman, chief of the NCI imaging program's molecular imaging branch.

Medicare started covering the scans last year, and medical device makers are creating combination CT/PET scanners, he added.

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On the Net:

New England Journal of Medicine: http://www.nejm.org

National Cancer Institute site on lung cancer: http://cancernet.nci.nih.gov/cancer—types/lung—cancer.shtmltesting