Risks of Radiation May Outweigh Benefits in Some Breast Cancer Patients

[Susan Gawarecki <loc@icx.net>]

Risks of Radiation May Outweigh Benefits in Some Breast Cancer Patients 

By Merritt McKinney 

WESTPORT, May 19 (Reuters Health) - A meta-analysis of randomized trials
of radiotherapy in breast cancer patients shows that the treatment is
associated with reduced local recurrence and breast cancer mortality,
but also with increased mortality due to other causes. 

For older women as well as women of any age who have a low risk of
recurrence, the risks of radiation may outweigh the benefits,
researchers report in the May 20th issue of The Lancet. 

Dr. Rory Collins, of the Clinical Trial Service Unit at Radcliffe
Infirmary, in Oxford, England, and other members of the Early Breast
Cancer Trialists' Collaborative Group reviewed the 10-year and 20-year
results of 40 unconfounded, randomized radiotherapy trials that included
19,582 women. All of the trials began before 1990. 

Overall, radiation prevented about two thirds of local recurrence,
regardless of patient characteristics or radiation type, Dr. Collins
told Reuters Health. According to Dr. Collins, radiation therapy appears
to translate into "moderate improvement in avoidance of breast cancer
deaths." He noted that the benefits of radiation tended to be greater in
node-positive women. 

When the results of all studies were combined, women who received
radiation did not have lower breast cancer mortality in the first 2
years, but after that, the annual breast cancer mortality was about 13%
lower than that of women who did not undergo radiation, according to the
report. 

Despite the reduced breast cancer mortality associated with
radiotherapy, however, overall mortality was actually higher in
radiation-treated women. Beginning 2 years after randomization, the
annual non-breast cancer mortality rate was 21.2% higher in women
treated with radiation. 

This increased mortality "appeared chiefly to involve an excess of
vascular deaths, perhaps due to inadvertent irradiation of the coronary,
carotid or other major arteries," the authors write. 

Overall, the 20-year survival rate was 37.1% in women treated with
radiation and 35.9% in controls. 

Based on 20-year survival, "There's a modest benefit [of radiation] for
younger women with node-positive disease under age 50," Dr. Collins
said. "For women who are at low risk of local recurrence...any benefit
is small, less than 1%." 

According to Dr. Collins, for older women with node-positive cancer,
deciding whether the benefits of radiation outweigh the hazards is
difficult. 

But in the report, the researchers state that if radiation techniques,
including ones that reduce carotid and intrathoracic exposure "can be
shown to yield most of the benefit while avoiding most of the hazard,
20-year survival could be moderately improved in a wider range of
patients." 

In an accompanying editorial, Dr. John M. Kurtz, of University Hospital
in Geneva, Switzerland, notes that the radiation techniques used today
differ greatly from those in the studies included in the review. 

Despite the differences and the lower overall mortality associated with
radiation in the review, Dr. Kurtz concludes that "the results of the
overview should be considered good news for radiotherapy, since they
firmly establish the reductions attainable in the risks of total
recurrence...and breast cancer mortality." 

He notes that the risk of vascular morbidity can probably be reduced by
refinements in radiation technique. 

However, Dr. Kurtz believes that the results of this meta-analysis
"should not dissuade clinicians from continuing to favor conservation
surgery and to provide patients with the advantages of breast
irradiation with tangential photon beams, which have not been clearly
implicated as a cause of vascular mortality." 

Lancet 2000;355:1739-1740,1757-1770. 
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Susan L. Gawarecki, Ph.D., Executive Director
Oak Ridge Reservation Local Oversight Committee, Inc.
136 S Illinois Ave, Ste 208, Oak Ridge, TN 37830
Phone (865) 483-1333; Fax (865) 482-6572; E-mail loc@icx.net 
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