Download New Study Shows Higher CVD Mortality in Breast Cancer Patients

New Study Shows Higher CVD Mortality in Breast Cancer Patien
Published on Cancer Network (http://www.cancernetwork.com)
New Study Shows Higher CVD Mortality in Breast Cancer
Patients Receiving RT
May 01, 2004 | Breast Cancer [1]
HAMBURG, Germany—Radiotherapy for breast cancer increases the risk of death from
cardiovascular disease (CVD), compared with patients who did not receive such treatment, according
to data from a large retrospective cohort study. Maartje Hooning, MD, a clinical epidemiologist from
the Netherlands Cancer Institute, Amsterdam, and lead investigator of this study, presented the
findings at the 4th European Breast Cancer Conference (abstract 291).
HAMBURG, Germany—Radiotherapy for breast cancer increases the risk of death from cardiovascular
disease (CVD), compared with patients who did not receive such treatment, according to data from a
large retrospective cohort study. Maartje Hooning, MD, a clinical epidemiologist from the
Netherlands Cancer Institute, Amsterdam, and lead investigator of this study, presented the findings
at the 4th European Breast Cancer Conference (abstract 291).
Dr. Hooning’s research team studied data from 7,247 patients with early breast cancer, who ranged
from 17 to 71 years of age. These patients had been treated for stage I-III breast cancer and had
been admitted to the Netherlands Cancer Institute or the Daniel den Hoed Cancer Center in
Rotterdam between 1970 and 1987. Patients have been followed for a median of 14 years, and 34%
have been followed for more than 20 years. For 92% of the patients, a complete medical status was
available up to January 1998.
The investigators compared mortality from cardiovascular disease in patients receiving radiotherapy
and nonirradiated patients. The study population’s cardiovascular mortality rates were than
compared with those of the general female population. The team also clearly documented the sites
of the radiation fields.
Compared with the general female population, the number of cardiovascular deaths in the study
population was within the normal range of expectancy. Further analysis showed a 2.2-fold increase
in cardiovascular deaths among patients who had received radiotherapy, compared with those who
had not (range of risk, 1.4 to 3.6). "In terms of absolute excess risk, this means 12 extra
cardiovascular deaths per 10,000 irradiated patients per year," Dr. Hooning said.
The nonirradiated group actually had a significantly lower cardiovascular mortality at 0.6-fold (range,
0.3 to 0.8) than the general female population, suggesting that the risk profile for breast cancer is
protective against cardiovascular disease. Dr. Hooning explained this apparent anomaly by saying
that a healthier life style after breast cancer may play a role.
"When you analyze the data, it is not such an unexpected development after all," Dr. Hooning said.
"Breast cancer is linked with a higher socioeconomic status, which is associated with better nutrition,
a lower risk of hypertension, and less obesity. So, as a result, breast cancer patients might indeed
have a lower risk profile for cardiovascular disease." The diagnosis of cancer may also have led
patients to improve their lifestyle. "Stopping smoking and losing weight through exercise and a
healthy diet may contribute to the lower cardiovascular mortality rate," Dr. Hooning said.
The radiation-related risk increased dramatically among patients who had more than 10 years of
follow-up. Patients treated before the age of 45 had an even greater radiation-related increased CVD
risk [Standardized Mortality Ratio (SMR) = 2.6]. This increased risk is thought to be caused by the
lower background risk of CVD in younger woman, compared with older woman.
The relative risk of CVD in woman who had received radiotherapy to their left chest wall was 1.6
times higher than the risk in patients receiving radiotherapy to the right side. Although not
significant, this increase was probably a direct side effect of the radiotherapy, since radiotherapy on
the left side affects a large part of the heart. This difference was especially noticed in woman who
received radiation following mastectomy, compared with those irradiated after breast-conserving
surgery.
"The good news is that the figures show that the risks of CVD with radiotherapy have decreased over
time," Dr. Hooning said. The cardiovascular disease mortality rate for patients treated before 1980,
for whom mastectomy was standard, was 1.9 times that of nonirradiated patients. For woman
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New Study Shows Higher CVD Mortality in Breast Cancer Patien
Published on Cancer Network (http://www.cancernetwork.com)
treated after 1980, this risk was down to 1.5 times that of nonirradiated patients.
This decrease in CVD deaths can be attributed partly to improvements in radiation therapy
techniques and changes in the way radiotherapy is given. "Today, for example, radiotherapy to the
parasternal field—the rectangular field along the breastbone—is given less frequently. But the findings
also provide strong support for all the research being done on minimizing the radiation dose to the
heart," Dr. Hooning said.
The research team is currently analyzing the incidence of CVD in the study population. Said Dr.
Hooning, "It is expected that this will give us a more accurate view of CVD risk than does mortality.
Even if we do not immediately notice any increased mortality risk in some patients, there may be an
increased incidence because it may take years before cardiovascular events are ‘translated’ into
actual deaths."
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s-receiving-rt
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[1] http://www.cancernetwork.com/breast-cancer
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