Radiation Cuts Risk of Breast Cancer Recurrence by Two-Thirds
May 18, 2000 -- Giving radiation therapy to women after they have surgery
for early-stage breast cancer significantly reduces the risk that their cancer
will return. But a new study of more than 20,000 women shows that radiotherapy
may increase the risks of dying from something other than breast cancer 10
years or more after the treatment.
Experts caution that women should interpret the findings carefully, since
the study involves data from trials done in the 1960s, '70s, and '80s, when
radiation techniques were different than they are today. Most of the deaths
from causes other than breast cancer are thought to be directly related to the
older radiation techniques, in which the heart and surrounding structures in
the chest and neck were exposed to the radiation beams.
Study co-author Rory Collins, MD, professor of medicine and epidemiology at
the University of Oxford in England, tells WebMD that the positive message of
the study is that it gives "absolutely clear" evidence that fewer women
are now dying from breast cancer, as well as showing that radiation cuts the
risk of the cancer's recurrence by two-thirds.
The study, published in the medical journal Lancet, found that in the
first 10 years after treatment, 9% of the women who received radiation after
surgery had a recurrence of cancer in the same area, compared with 27% of the
women who did not receive radiation.
In the first two years after treatment, radiation had no apparent effect on
deaths from causes other than breast cancer. But from that point on, the annual
death rate was an average of 21% higher for all women who received
Still, by keeping their cancer away, radiation made a positive difference
for these women. In terms of overall survival, the groups were nearly equal:
Women who got radiation had a 2% better survival rate 10 years after treatment
than women who did not; by 20 years, the difference in death rates between the
two groups was only 1.2%.
"In all of the women studied in these trials, there was no effect on
overall survival," Collins tells WebMD. "There was a decrease in breast
cancer death and an increase in non-breast-cancer death for all of the
Heart-related problems caused the deaths of most of the women who died from
something other than breast cancer. The risk of dying from a cause other than
breast cancer was lowest for women who were 50 and younger at the time of their
breast-cancer diagnosis, and highest for women who were 60-69 at that time.
"For the younger women, even with the older radiotherapy regimens, the
benefits outweigh the risks," Collins says. "For older women or for
women with very low risk of recurrence, it's not clear that the benefits
outweigh the risks seen in these studies."