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Special MRI Offers Quick Assessment of Brain Cancer Therapy
MONDAY, March 28 (HealthDay News) -- A cutting-edge magnetic resonance imaging (MRI) scan can radically reduce the time brain cancer patients and their doctors must now wait before seeing whether treatments targeting tumor growth are working, a new study suggests. Researchers from the University of Michigan report that this special scanning method -- known as diffusion MRI -- measures water movement in the brain, and is designed to be used only three weeks into a seven-week treatment regimen of either chemotherapy or radiation. They note that since water movement is slowed or blocked by the presence of tumor cells, any change in water flow mid-treatment would indicate a change in the size of the tumor. Currently, traditional MRIs that measure brain tumor growth can only be successfully administered approximately six weeks after such treatments have ended, the researchers said. "The fact that we can discover success or failure so early will give us time to adjust the treatment, if necessary," said study co-author Dr. Theodore S. Lawrence. "If you make this discovery a week after treatment is done it would be much less useful. It''s really very exciting." The findings appear in the early online March 28 edition of the Proceedings of the National Academy of Sciences. Lawrence and his colleagues from the University of Michigan Comprehensive Cancer Center followed the treatment histories of 20 men and women who were diagnosed with malignant brain tumors. Treatment for all the patients included radiation, chemotherapy, or a combination of both therapies. Before treatment began, all the patients underwent both a diffusion MRI and a traditional MRI, followed by another diffusion MRI three weeks into treatment. Traditional MRIs were administered starting four weeks after treatment was completed. The researchers found that after treatment, six of the patients had experienced more than a 50 percent decrease in the size of their tumor. The tumors of another six patients had either shrunk to a lesser degree or actually grown slightly in size. The remaining eight patients had experienced more significant tumor growth and were determined to have progressive brain cancer. Most critically, the authors noted that the results of the diffusion MRIs administered at the three-week interval perfectly matched the results of the traditional MRIs administered post-treatment in all 20 cases. They concluded that the diffusion MRI method appears to be able to accurately predict the success and failure of a range of treatment regimens a full 10 weeks earlier than a traditional MRI. And they expressed hope that patient treatment could be greatly enhanced by speeding up the ability to identify ineffective treatment. "It''s a major step in the right direction of attempting to individualize treatment response and patient care of oncology patients," said study co-author Dr. Brian Ross. "If I''m the patient and I''m sick with the side effects of a treatment and I''m wondering if this is working because I''m feeling really bad, this would encourage me to suck it up and keep going. Because I know the treatment is working, or because I know I had better change treatment." The researchers noted, however, that a diagnosis of primary brain cancer -- namely cancer first appearing in the brain-- offers little hope for a favorable outcome. In 2004, more than 18,000 new cases of primary brain cancer were diagnosed in the United States, with almost 13,000 of these patients expected to ultimately die of this disease within a relatively short period of time. But Lawrence said diffusion MRI technology could markedly improve patient care. "This scanning method doesn''t just give a yes or a no", he said. "It also determines which parts of the tumor are responding and which parts are not responding. So this technology permits us to even individualize therapy to different parts of the tumors during the course of the treatment." Both authors pointed out that the traditional MRI equipment already in hospitals throughout the United States are capable of handling diffusion scans when enhanced with relatively inexpensive software and small work stations to process the data. And both doctors expressed optimism that further research into the use of diffusion scanning may ultimately broaden the benefit of the technology to assess treatment for breast, liver, head, and neck cancers. Ross acknowledged, however, that the introduction of such a significant change in medical treatment faces hurdles. "Currently, insurance companies will not reimburse for an MRI mid-treatment," he noted, citing one example. "It''s not clinically indicated today because there''s not been a reason to do it. So that''s the next issue we have to address -- to convince the regulatory agencies that this is something that is both cost-effective and extremely valuable for patient care." Dr. Ashwatha Narayana, the head of the brain tumor section in radiation oncology at Memorial Sloan-Kettering Cancer Center in New York City, also needs some convincing. "Early responses to treatment do not always predict the final outcome," he said, suggesting that taking the pulse of a therapy at three weeks might not account for the late-blooming benefits of treatment that doctors sometimes uncover much later down the line. "So we need to be a little cautious about this type of screening method." "But what [the researchers] have done is a very impressive job," Narayana added. "It''s very novel, and a step in the right direction." More information To learn more about brain cancer, visit the American Cancer Society.
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