WEDNESDAY, Oct. 15, 2008 (HealthDay News) -- Young women receiving radiation after having surgery for breast cancer are at increased risk of developing a new tumor in the opposite -- or contralateral -- breast, a new Dutch study suggests.
And the risk jumps even higher if the woman also has a significant family history of breast cancer.
The study, appearing online in the current issue of the Journal of Clinical Oncology, looked at fairly recent radiation techniques (1970 to 1986), but experts pointed out that these techniques are continually being refined and improved.
"It's a very interesting study, [but] radiation techniques have changed dramatically over the last 25 years and a lot of these patients were treated with much older techniques," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La.
The risk of contralateral breast cancer was also greatest when three or more family members had a history of breast cancer, indicating that some of the women in the study might have the risk-raising BRCA1 or 2 genetic mutations. These mutations weren't tested for in the study.
"Today, we're able to better identify women who may not be breast-conservation candidates," Brooks said.
Study author Maartje J. Hooning, of the department of medical oncology at Erasmus Medical Center Daniel den Hoed Cancer Center in Rotterdam, said that even though "radiation techniques of today will lead to a lower dose to the contralateral breast than the techniques presented in our study, treating clinicians should be aware of the existing dose-response relationship for risk of contralateral breast cancer. Especially in young women, the radiation dose to the contralateral breast should be kept as low as possible."
According to the American Cancer Society, radiation therapy is usually employed to destroy lingering cancer cells after a lumpectomy (also known as breast-conserving surgery), after a mastectomy involving a tumor larger than 5 centimeters in size, or when cancer is found in the lymph nodes.
In general, according to the study, women diagnosed with breast cancer in one breast have three to four times the risk of developing a new cancer in the other breast.
Much of this increased risk has been attributed to genetic predisposition, hormonal risk factors and other common causes. But there remains the possibility that treatment regimens for the first breast cancer, including chemotherapy and radiation, might also play a part.
For this study, the researchers looked at more than 7,000 one-year survivors of breast cancer who had been under the age of 71 when they were diagnosed. All were treated from 1970 to 1986 in the Netherlands.
Overall, radiation therapy did not significantly increase the risk of a new cancer in the opposite breast.
However, women treated with radiation before they turned 45 had a slightly increased risk of a new tumor in the other breast, while women receiving radiation before they were 35 had a 78 percent increased risk.
Women receiving post-lumpectomy radiation before the age of 45 had a 1.5-fold increased risk of contralateral breast cancer when compared with women who had undergone post-mastectomy radiation, according to the study.
Younger women with a strong family history of breast cancer who had also undergone post-lumpectomy radiation had a 3.5-fold increased risk of contralateral breast cancer, the study found.
"Now that we know that young patients with affected relatives are at increased risk of contralateral breast cancer following radiation therapy, we should define in more detail the subgroup that is genetically susceptible to radiation-induced breast cancer," Hooning said.
The American Cancer Society has more on radiation therapy for breast cancer.