Women
with Hodgkin's Treated with Radiation at Increased Risk of
Developing Breast Cancer
According to a recent article published in The Journal of
the National Cancer Institute, treatment utilizing higher
doses of radiation therapy to the chest in women with Hodgkin's
increases the risk of a patient developing breast cancer.
However, treatment involving chemotherapy in addition to radiation
therapy reduces the risk of developing breast cancer, compared
to radiation therapy alone. Women who have received radiation
to the chest are recommended to receive life-long screening
for the early detection of breast cancer.
Hodgkin's disease is a cancer of the lymph system, which
is part of the immune (infection fighting) system that includes
blood vessels, bone marrow, lymph nodes and lymph vessels
that are present throughout the body. It also includes organs
such as the spleen, thymus and tonsils. This cancer is characterized
by the presence of the uncontrollable growth and division
of atypical white blood cells (immune cells) that crowd lymph
tissue, suppressing the formation and function of other cells
normally found in this tissue. Patients with Hodgkin's disease
are treated with chemotherapy and often radiation therapy
to sites where cancer remains bulky. The chest is one area
where radiation may be used, as lymph nodes in that region
can be involved with the disease. Previous studies have indicated
that survivors of Hodgkin's disease have a higher rate of
developing breast cancer than those in the general population;
however, the cause of the increased breast cancer rate has
not been well defined.
Researchers from the Netherlands and the United States recently
conducted a clinical study in an attempt to define an association
between treatment for Hodgkin's disease and the development
of breast cancer. The study involved over 200 female patients
who had been diagnosed with Hodgkin's disease prior to the
age of 41; 48 of whom developed breast cancer 5 or more years
after diagnosis and 175 of whom did not develop breast cancer.
Researchers evaluated and compared treatment between the two
groups of patients, including dose of radiation, chemotherapy
and reproductive factors. Overall, the incidence of developing
breast cancer was approximately halved in patients treated
with both chemotherapy and radiation therapy, compared to
those treated with radiation therapy alone. Patients treated
with radiation therapy only were 12.7 times more likely to
develop breast cancer if the radiation dose was higher than
38.5 Gy, compared to 4 Gy or lower. Patients treated with
both chemotherapy and radiation therapy did not experience
an increased rate of breast cancer with increased doses of
radiation therapy. This reduction in the incidence of breast
cancer correlated with treatment-induced menopause, as 69%
of women treated with chemotherapy plus radiation therapy
entered menopause, compared to only 9% of women treated with
radiation therapy only. The researchers speculate that the
chemotherapy induces menopause and reduces the amount of available
female hormones in the body that stimulate the growth of a
common type of breast cancer.
The researchers concluded that treatment for Hodgkin's disease
involving radiation therapy alone, particularly in higher
doses, greatly increases the risk of developing breast cancer
in women. However, with the addition of chemotherapy, this
risk can be greatly reduced. Patients with Hodgkin's disease
should discuss the risks and benefits of radiation with or
without chemotherapy in their treatment regimen with their
physician. Women who have received radiation therapy to the
chest should receive life-long screening for breast cancer.
Reference: van Leeuwen F, Klokman W, Stovall M, et al. Roles
of radiation dose, chemotherapy, and hormonal factors in breast
cancer following Hodgkin's disease. The Journal of the National
Cancer Institute. 2003;95:971-980.
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