Women with Hodgkin's Treated with Radiation at Increased Risk of Developing Breast Cancer

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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