PET scans superior in revealing response to treatment for gastrointestinal stromal tumors

In fighting cancer, the sooner doctors can determine how a patient will respond to a particular therapy, the more effective overall treatment will be. Researchers have now shown that 18F-FDG PET scans are better than CT scans at predicting response to imatinib mesylate, a drug that has recently been found effective in treating gastrointestinal stromal tumors (GISTs).

The result is significant, as the PET scan allows doctors to determine if the therapy regimen is working very early in the treatment process, providing information that will allow physicians and patients to decide as soon as possible whether to continue treatment with imatinib mesylate or try a different therapy.

The study, which was conducted by researchers at the University of Texas M.D. Anderson Cancer Center in Houston, Texas, was published in the January 2004 edition of The Journal of Nuclear Medicine. They conducted the retrospective analysis by examining the sensitivity and predictive values of PET and CT scans taken prior to therapy and then again two months after imatinib mesylate treatment had begun. While there was no significant statistical difference between the pretreatment accuracy of the two different types of scans, PET was more effective in early assessment of the patients’ responses to the drug.

“In our judgment,” the researchers stated, “18F-FDG PET is an excellent prognostic tool for early assessment of response to imatinib mesylate therapy.” The researchers further concluded that there is not significant value in the use of CT to monitor early response to this treatment.

“The Role of 18F-FDG PET in Staging and Early Prediction of Response to Therapy of Recurrent Gastrointestinal Stromal Tumors” was written by Isis Gayed, MD, Homer Macapinlac, MD, Nancy Swanston and Donald Podoloff, MD from the Department of Nuclear Medicine; Thuan Vu, MD and Revathy Iyer, MD from the Department of Diagnostic Radiology; and Marcella Johnson, MS from the Department of Biostatistics; all from the M.D. Anderson Cancer Center, University of Texas in Houston, Texas.

Copies of the article and an image related to the study are available to media upon request to Kimberly A. Bennett. Current and past issues of The Journal of Nuclear Medicine can be found online at jnm.snmjournals.org. Print copies can be obtained at $20 per copy by contacting the SNM Service Center, Society of Nuclear Medicine, 1850 Samuel Morse Drive, Reston, VA 20190-5315; phone: (703) 326-1186; fax: 703-708-9015; email: servicecenter@snm.org. A yearly subscription to the journal is $210 for individuals and $318 for institutions. A subscription is a Society of Nuclear Medicine member benefit.

The Society of Nuclear Medicine is an international scientific and professional organization of more than 14,000 members dedicated to promoting the science, technology, and practical applications of nuclear medicine. The SNM is based in Reston, VA.