“Gamma knife” treatment can extend cancer survival

By Will Boggs, MD

NEW YORK (Reuters Health) – Many patients can survive for
years after undergoing effective gamma knife radiosurgery for
cancers that have spread to the brain, according to a new
report.

As many as 40 percent of patients with systemic
malignancies have cancers that spread (metastasize) to the
brain, the authors explain, and radiosurgery of these
metastases can extend survival to 13 months or longer,
depending on the tumor type.

Dr. Douglas Kondziolka from the University of Pittsburgh
Medical Center, Pennsylvania and colleagues assessed 44
patients who survived more than four years after undergoing
radiosurgery to determine clinical and treatment patterns that
affect the outcome.

Gamma knife radiosurgery, which requires no surgical
incision, directs concentrated gamma radiation to a specific
target, reaching brain tumors once considered inoperable.

The study patients represented 6.5 percent of the patients
with brain metastases who underwent radiosurgery between 1988
and 2000 at their institution. The average survival time of
these patients was 68 months, and 16 patients remained alive at
the time of last follow-up, with a maximum survival of 156
months so far.

At the last follow-up, 99 of 133 (74.4 percent) brain
metastases had regressed, 22 remained unchanged in volume (16.5
percent), and 12 (9 percent) had enlarged, researchers report
in the medical journal Cancer.

Twenty-one of the patients required additional radiosurgery
procedures, the researchers note, with one patient (who lived
for more than 10 years) requiring seven radiosurgeries.

Compared with patients who died within the first three
months after radiosurgery, the survivors had no differences in
age; sex; percentage of lung cancer, melanoma, or kidney
cancer. There were also no differences in radiosurgery dose;
use of prior whole brain radiation therapy; volume of the
largest tumor; or total tumor volume.

Patients who lived more than four years had higher
pre-treatment scores on physical functioning; fewer metastases,
and less cancer in other parts of the body than did patients
who died soon after radiosurgery, the investigators observe.

“Despite our traditional methods to predict how patients
with cancer will fare (cancer type, extent of cancer), some
patients ‘beat the odds’ and do much better than anyone might
have predicted,” Kondziolka told Reuters Health.

To increase the number of these patients, “we should
continue to offer comprehensive cancer care, whenever
appropriate,” even for patients with poor prognostic factors,
such as brain metastases, Kondziolka added. “When I discuss
things with patients, I offer them hope that perhaps they will
do much better than the textbooks might predict.”

SOURCE: Cancer, December 15, 2005.