The version of SRS that Rosseau uses is called Gamma Knife, but the knife is not a knife at all. A helmetlike device is placed on the patient’s head. Then 201 separate beams of high-energy cobalt radiation are emitted from different points through the helmet. Guided by computer, they all meet at the site of the tumor. They pass through healthy tissue on the way there, but because each beam represents less than a half percent of the total dose, they damage no tissue until they converge. There is no pain and no need for general anesthesia.
Rosseau’s trial was announced last fall; once under way — the protocol is in the peer-review phase — it’s expected to take a year to complete. She will examine and, if necessary, treat, 50 women who have recently been diagnosed with breast cancer and who had four positive lymph nodes and/or known nonbrain metastases.
"We want to establish how often these women will be discovered to have asymptomatic brain cancer, so that we can infer from this group what a screening protocol should look like," Rosseau says. "Exciting" is what she calls it. It’s also exciting to know that a patient admitted for screening in the morning can be home for dinner, her cancer treated before a full day has passed.
Quality of Life
Andrew D. Seidman, MD, a breast cancer specialist at Memorial Sloan-Kettering Cancer Center in New York City, is recognized worldwide for his clinical investigations of new treatments. He is doing research for the U.S. Department of Defense Breast Cancer Research Program on the problem of brain metastases and believes that Herceptin may be doing such a good job of controlling the growth of any cancer that may have metastasized in the rest of the body that it allows women to live long enough to develop brain tumors. (Herceptin doesn’t cross the blood-brain barrier and therefore won’t work there.)
"There is no prospective study [one that follows patients into the future] that shows a survival advantage for radiologic screening of breast cancer patients before they have headaches or neurological symptoms," Seidman says. "However, saying there’s no survival advantage doesn’t mean that there’s no advantage … I have gotten into the habit of doing brain MRI scans on women who are HER-2/neu positive [meaning they are at a higher risk for brain metastases], even in completely asymptomatic women, every six to 12 months or so."
And Seidman does find tumors — sometimes one, sometimes two; they are rarely widespread. He finds them in women who feel well and who have no headaches or other symptoms. He finds them when they would not be found during the usual "how am I doing?" visits.
"With Gamma Knife and SRS, we can reduce neurological morbidity rather than watching and waiting," Seidman says. "We may be able to prevent very disabling symptoms."
The potential trouble with not screening, Seidman says, is that by the time the brain metastases have begun causing symptoms and are discovered, there may be eight rather than the one or two he’s finding. "By then, Gamma Knife is not an option. Use of whole-brain radiation is standard at that point," he says. The patients may be left with neurological symptoms from the tumors themselves — ranging from seizures and headaches to loss of balance or paralysis, depending on where the tumors are located — as well as cognitive dysfunction from the radiation. "It’s not that dissimilar to patients who have strokes." In other words, it can be crippling. Survival times at that point are in the range of six to 12 months. "We see a very, very different picture when we detect one or two asymptomatic brain metastases and they are treated with localized therapies," Seidman says. "Many of these women will go on to live five and six and seven years with their metastatic disease."
With the movement to know and act preemptively gaining momentum, the number of institutions that are incorporating brain and other organ scans as part of follow-up treatment for people with known metastases is increasing. There is a spread of technology and a lot of advertising going on: "Get yourself screened; I did, and I’m lucky I found this problem." Screening in general — for everything — is a booming business.