CHICAGO - When the world's top specialists in removing and treating brain tumors talk about surgery, they never utter the word cure.
more stories like thisThat's because a brain tumor is much like a wildfire, always seeking new territory to conquer. An operation can douse the hottest part of the inferno, but doctors know that dangerous embers remain behind.
As a result, patients such as Senator Edward M. Kennedy, whose malignant tumor was excised Monday by physicians at Duke University Medical Center in North Carolina, must endure radiation and chemotherapy in an attempt to neutralize stray cancer cells.
"These tumors are very aggressive," said Dr. Mark Gilbert, a neuro-oncologist at M.D. Anderson Cancer Center in Houston. "They cannot be treated by surgery alone."
A statement released yesterday by Kennedy's office said that the senior senator from Massachusetts had experienced no complications from his operation and "has been walking the hallways, spending time with family, and actively keeping up with the news of the day." The statement predicted he would leave Duke in about a week.
At the same time Kennedy was undergoing surgery Monday, brain tumor specialists here were revealing their latest research at an international scientific meeting of cancer doctors, showing modest progress in treating brain cancer and advances in understanding its underlying biology. Specialists debate how much surgery can extend patients' lives, but studies presented this week and previously have shown that a three-year-old form of chemotherapy, when combined with surgery and radiation, adds at least several months to the lives of patients.
Once the surgeon's work is finished, follow-up treatment proceeds on two fronts: in the region where the tumor once sat and in more distant corners of the brain.
Radiation, carefully calibrated and narrowly targeted, aims at the tumor bed and, usually, a 2-centimeter ring around it.
"So radiation provides some control of the tumor at and around where the original tumor was, but still there are individual tumor cells that might have migrated much further out" in the brain, said Dr. Deepa Subramaniam, director of the Brain Tumor Center at Georgetown University's Lombardi Comprehensive Cancer Center in Washington. "And it is those cells that are targeted by chemotherapy."
A few weeks after surgery is completed, patients begin receiving radiation and chemotherapy simultaneously. Typically, the course of radiation lasts six weeks, with five treatments each week.
Patients also start a daily dose of chemotherapy called temozolomide, which comes in a pill. Once radiation is finished, patients continue taking the pills for at least the next six months. The doses become less frequent, with pills taken on only five consecutive days in each month.
Unlike some other forms of chemotherapy, temozolomide usually does not cause patients' hair to fall out or severe bouts of nausea.Continued...
Even after surgery, radiation, and chemotherapy, few patients with malignant brain tumors survive five years after their initial diagnosis. That reflects both the limited tools doctors have to fight the disease, as well as the unusually insidious nature of brain tumors.
Gilbert said there is controversy in the field about whether surgery extends patients' lives. In part, Subramaniam said, that's because researchers have never conducted a gold-standard trial to confirm the benefits of brain surgery. Such a study, in which some patients would have their tumor removed while others would not, would be impractical now, she said.
"No patient would be willing to be in a trial like that," Subramaniam said. "I almost feel it would be unethical, based on the vast amount of evidence we have to support" the removal of brain tumors.
"If a tumor was in a location where it can be taken out safely," she said, "I would want it taken out."
Less rigorous studies have suggested that surgery helps patients live longer, by maybe four months. But the most widely cited of those studies were done in an era before patients received temozolomide, which could add to surgery's benefit.
At the American Society of Clinical Oncology conference that just concluded, researchers presented studies that affirmed the effectiveness and safety of temozolomide, while other scientists' work showed the potential of a drug now used to treat other tumors.
That medication, Avastin, aims to choke off the nutrients tumors need to thrive. Brain tumors, as much as any other malignancy, are adept at engineering their spread by sprouting blood vessels, a process called angiogenesis that was discovered by the legendary Children's Hospital Boston researcher Judah Folkman, who died earlier this year. Avastin interrupts angiogenesis, and the drug is now being used in brain tumor patients whose growth recurs.
For example, one study released Monday showed that when patients whose tumors had returned received Avastin in combination with a second drug, 22 percent were still alive two years later. That is considered an improvement over previous treatments, albeit a modest gain.
"Patients are living months longer or even a year, but it always comes back," said Dr. Patrick Wen, clinical director of the Center for Neuro-oncology at the Dana-Farber Cancer Institute in Boston, who also practices at Brigham and Women's Hospital.
No comments:
Post a Comment