Breast Cancer Risk Found High After Chest Radiation for Hodgkin’s
Young women treated with high-dose chest radiation for Hodgkin’s lymphoma have 10 times or greater the risk of developing Breast cancer later in life than do women in the general population.
That cumulative absolute risk assessment emerged from an analysis of data from a population-based cohort of 3,817 women diagnosed and treated for Hodgkin’s lymphoma between 1965 and 1994.
It contrasts with previous estimates of the cumulative incidence of Breast cancer after treatment of young women for Hodgkin’s disease, ranging from 4.2% to 34% at 20 to 25 years of follow-up, reported Lois B. Travis, M.D., of the National Cancer Institute here and colleagues.
They characterized the previous risk estimates as smaller and not likely to be as accurate.
For women treated at age 25 with a chest radiation dose of 40 Gy or more without alkylating agents, Dr. Travis and colleagues reported in the Oct. 5 issue of the Journal of the National Cancer Institute, the cumulative absolute risk of developing Breast cancer at key ages, versus risk in the general population, was:
- Age 35: 0.4% (95% confidence interval=0.3%-0.6%) versus 0.04% for the general population.
- Age 45: 4.9% (95% CI=3.2%-7.4%) versus 0.5% for the general population.
- Age 55: 29.1% (95% CI=13%-27.4%) versus 2% for the general population.
They found that cumulative absolute risks were lower in women treated with alkylating agents, a 40% reduction in Breast cancer risk.
Breast cancer is a malignant growth that begins in the tissues of the breast. Over the course of a lifetime, one in eight women will be diagnosed with breast cancer.
Causes, incidence, and risk factors
There are several different types of breast cancer. Ductal carcinoma begins in the cells lining the ducts that bring milk to the nipple and accounts for more than 75% of breast cancers.
Lobular carcinoma begins in the milk-secreting glands of the breast but is otherwise fairly similar in its behavior to ductal carcinoma. Other varieties of breast cancer can arise from the skin, fat, connective tissues, and other cells present in the breast.
“It is sobering to realize that, by age 50 years, many of the women treated with high-dose chest radiotherapy had already exceeded the lifetime risk of developing Breast cancer in the general population (in which one in eight women will develop Breast cancer, or 13.4%),” they wrote.
Nevertheless, the investigators noted that “the gains in long-term survival provided by successful radiotherapy and chemotherapy outweigh the associated risks of Breast cancer and other late sequelae.”
They also pointed out there have been improvements in radiation therapy that “will likely result in lower risks of Breast cancer in the future.”
Definition
Hodgkin’s lymphoma is a malignancy (cancer) of lymph tissue found in the lymph nodes, spleen, liver, and bone marrow.
Causes, incidence, and risk factors
The first sign of this cancer is often an enlarged lymph node which appears without a known cause. The disease can spread to adjacent lymph nodes and later may spread outside the lymph nodes to the lungs, liver, or bone marrow.
The cause is not known. The incidence is 2 in 10,000 people. Hodgkin’s lymphoma is most common among people 15 to 35 and 50 to 70 years old.
At the same time, they added, there have been improvements in chemotherapy for Hodgkin’s disease that might obviate radiation therapy. “Newer combination chemotherapy protocols (such as doxorubicin, bleomycin, vincristine, and dacarbazine) confer minimal ovarian toxicity, in contrast to the established ovarian suppression that is associated with MOPP chemotherapy,” they wrote.
In an editorial accompanying the study, Dan L. Longo, M.D., of the National Institute on Aging, called the results “shocking.”
Radiation therapy should not be used for treating Hodgkin’s disease when alternative approaches, such as combination chemotherapy alone, have similar success in curing the disease without the magnitude of late fatal complications, Dr. Longo argued.
“We need to stop exposing women to the risk of subsequent Breast cancer (and other malignancies and heart disease) by needlessly using radiation therapy as a component of their Hodgkin’s disease treatment,” he wrote.
Revision date: July 3, 2011
Last revised: by Dave R. Roger, M.D.