Scans During Radiation Treatment Help Lung Cancer Patients

FRIDAY July 20, 2007 -- Ordering a PET scan for patients undergoing radiation lung cancer treatment may help doctors determine optimal therapy, a new study suggests.

PET, or positron emission tomography, scans have been traditionally used after radiation treatment for lung cancer to find out whether the tumor responded to treatment and to assess the patient's prognosis.

The new study, which is in the July 20 issue of the Journal of Clinical Oncology, was a pilot study of 15 people with early-stage non-small-cell lung cancer.

Before beginning radiation therapy, 3 to 4 weeks into treatment, and then three months after completing treatment, researchers used FDG-PET scans to determine how the participants' tumors were responding to treatment. An FDG-PET scan uses radioactive labeled glucose, which is drawn to cells that are being metabolized quickly. If a tumor is responding to treatment, it would show decreased FDG activity.

The researchers found a strong correlation between tumor responses during treatment and responses three months after completion of treatment.

"This demonstrates that PET scans can be performed earlier during the course of radiation treatment, which will allow us to modify the treatment regimen before the treatment is completed. Our sample size was small, but the results are very promising," lead study author Feng-Ming Kong, assistant professor of radiation oncology at the University of Michigan Medical School, Ann Arbor, said in a prepared statement.

In the past, there had been concern that the reaction of normal tissue to the radiation would get in the way of determining whether the tumor was shrinking. But Kong's study found that that testing during treatment may be beneficial in that respect.

"The confounding effect on normal tissue is not as significant during treatment as it is after treatment, which is a big surprise," Kong said.

"The PET scan is better to perform during the course of treatment instead of months after treatment. It avoids the normal tissue confounding effect and allows the radiation therapist to modify the doses if necessary," she said.

The Michigan team is continuing to study PET scans in a larger number of patients. Future research will be needed to determine if changing the dose of radiation in response to PET scans taken during treatment will lead to better outcomes.

More information

The U.S. National Cancer Institute has more about lung cancer.

Posted: July 2007


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