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WEDNESDAY, July 2, 2003 (HealthDayNews) -- Doctors have long known that radiation therapy increases the risk that people with Hodgkin's disease might develop other forms of cancer, including blood malignancies and solid tumors.
In young women with Hodgkin's disease, the threat of breast cancer is a particular concern following radiation.
But new research suggests this hazard can largely be avoided with careful attention to the hormones of women undergoing treatment for Hodgkin's disease. In particular, drugs that interfere with the sex hormone estrogen -- such as the cancer drug tamoxifen -- may help.
"Tamoxifen has not been used in this population, but it might be something that we should consider," says research leader Flora van Leeuwen, an epidemiologist at the Netherlands Cancer Institute in Amsterdam.
A report on the findings appears in the July 2 issue of the Journal of the National Cancer Institute.
Hodgkin's disease, also known as Hodgkin's lymphoma, is a blood-related cancer that affects some 7,000 people a year in the United States, according to the Leukemia and Lymphoma Society. Treatment advances since World War II, including radiation and a variety of drug combinations, have greatly improved the odds for patients with the disease, and five-year survival rates hover around 90 percent.
Still, the threat of "secondary" cancers brought on by treatment clouds the successes of Hodgkin's therapy. Although many of these secondary malignancies aren't especially serious, some can be life-threatening.
The new study made two important findings, says van Leeuwen.
First, it showed that a woman's risk of breast cancer after radiation treatments for Hodgkin's disease climbed based on the dose she received. Women who got the most radiation -- at least 38.5 grays to their breast -- had 4.5 times the risk of developing breast cancer as those who got less than 4 grays.
"In Hodgkin's disease treatment, the mediastinal lymph nodes are irradiated and various portions of the breast receive different doses" in the process, van Leeuwen says. "Calculating this dose was a labor-intensive part of the study, but crucial."
The chances that radiation for Hodgkin's disease would promote breast cancer dropped sharply, though not back to normal, in women whose treatment also called for chemotherapy, van Leeuwen says. Compared with women who received radiation alone, those who also underwent chemotherapy had about a 60 percent smaller risk of breast cancer, the study found.
The likely reason: Chemotherapy can hasten the onset of menopause, van Leeuwen says. Since menopause is a hormone-suppressed state, and many cases of breast cancer are sparked by the female sex hormone estrogen. Inducing menopause may blunt the ability of radiation to trigger breast tumors, she says.
"We already knew that radiation produces breast cancer," van Leeuwen says. "We now know with this study that with higher [doses], the risk is higher, but we now see that there is a way to substantially reduce the risk of these cancers."