Breast
Cancer Radiation Treatment Time Shortened
A sophisticated radiation therapy system safely
allows the delivery of a higher daily dose for breast cancer patients
and shortens the treatment time for women from six or seven weeks to
just four, researchers say.
The research team used intensity-modulated radiation
therapy, or IMRT, a system that is more accurate at targeting the radiation,
say researchers reporting in the International
Journal of Radiation Oncology Biology Physics.
The scientists wanted to see if treatment time could
be shortened and the daily dose increased without any more ill effects
than using the standard treatment.
"It's a bigger daily dose, but we feel it is more
accurately and evenly distributed with IMRT," explains lead researcher
Dr. Gary Freedman, a radiation oncologist at Fox Chase Cancer Center
in Philadelphia.
Dr. Freedman says physicians now have more options
than ever before in treating breast cancer.
"We have great evidence that lumpectomy and radiation
is equal, in terms of survival and cure rate, to mastectomy," at least
for women with smaller tumors, he says.
Even so, the length of treatment time can still
present problems.
"There are many women who balk at the six- or seven-week
treatment length because of perceived inconvenience, or they have to
travel a lot every day [to get to treatment]," notes Dr. Freedman.
The
length of treatment time for radiation therapy, prescribed in combination
with a lumpectomy when
a woman has breast
cancer, is "a very hot issue right now in radiation," explains Dr.
Freedman.
Some studies are looking at one-week treatment with
partial-breast radiation, he says, using both external beam radiation
and implanted radioactive seeds.
But this approach, says Dr. Freedman, is appropriate
only for a very select group of women with the smallest of breast cancers.
"My study is meant to be more inclusive," he
says.
His team, which also included physicians from the
University of Pennsylvania, treated 75 women, averaging 52 years of
age, with a higher than typical dose of daily radiation, and then followed
them to check for side effects.
"It's not a higher total dose," stresses Dr. Freedman.
In traditional six- or seven-week treatments, a total of 60 grays (a
unit for absorbed radiation) or Gys are given. In the study, the total
over the four weeks was 56 Gy.
The technique, not yet widespread, uses a computer-controlled
X-ray accelerator to deliver very precise doses of radiation to the
tumor or to specific areas within the tumor.
Dr. Freedman says this specificity minimizes radiation
exposure to tissues around the tumor.
"So far, we have found that the immediate side effects
of treatment were not increased over what we have seen with six or
seven weeks of treatment," he says.
Radiation can cause skin toxicity and inflammation,
for instance, but the four-week treatment results compared favorably
with the results seen for conventional six- or seven-week treatment.
While some women did encounter skin problems, the
skin toxicity resolved within six weeks of treatment. And the skin's
cosmetic appearance was back to its pre-treatment look six weeks after
treatment ended.
"We will follow [these patients] for five years," says
Dr. Freedman says, to be sure no long-term problems result.
While previous studies have found that women who
got radiation treatment in the 1980s appear to be at higher risk of
heart disease than women in the general population, Dr. Freedman says
he believes IMRT will better protect the heart.
"We definitely reduced the dose received by the
heart; we assume that means even less heart disease risk down the road," he
emphasizes.
There is one downside, though: IMRT is not yet widely
available, says Dr. Freedman.
Other experts said the study has both its strengths
and its limitations.
Dr. Frank Vicini, chief of oncology at the Beaumont
Cancer Institute, notes that the study had only 75 patients and needs
more validation through other studies. Like Dr. Freedman, he also points
out that the technology is not widely available.
More study will be done, he predicts. A radiation
study group is already discussing trials, says Dr. Vicini.
There are other critical questions yet to be answered
about any potential for long-term toxicity and recurrence, adds Dr.
Shawna Willey, at Lombardi Comprehensive Cancer Center at Georgetown
University.
"If long-term toxicity and recurrence are the same
as for longer treatments, most women will opt for four weeks," she
predicts.
Always consult your physician for more information.
|
