People who have been treated for cancer have a higher risk of developing a second cancer or another serious medical condition because of the treatment, compared to people who haven't been treated for cancer. A study found that women who had received hematopoietic cell transplantation (HCT) to treat different types of cancer (mainly cancers of the blood and bone marrow) had a higher risk of developing breast cancer years after that treatment, compared to women who did not get HCT. Women who were young when they received HCT or received radiation to the whole body before getting HCT were more likely to have increased risk of breast cancer.
HCT treatment injects stem cells into the bloodstream. These stem cells can help the bone marrow begin to produce cells that it normally produces when it's healthy (such as red blood cells and white blood cells). HCT is usually done when bone marrow stops working properly because of certain cancers or because of cancer treatment. Certain other medical conditions that aren't cancer also can cause bone marrow failure and are treated with HCT. The stem cells used in HCT treatment can come from the person being treated (stem cells are removed before the treatment that shuts down the bone marrow) or from a matched donor. A bone marrow transplant is an example of HCT.
Among the more than 3,000 women in this study, 11% who were living 25 years after receiving HCT had been diagnosed with breast cancer. Whether or not the women received total body irradiation before HCT made a big difference in the risk of being diagnosed with breast cancer. Among the women living 25 years after HCT, 17% of women who received total body irradiation before HCT had been diagnosed with breast cancer, but only 3% of women who received HCT but DIDN'T get total body irradiation were diagnosed with breast cancer.
The researchers concluded that a woman who receives total body irradiation before HCT is 4 times more likely to be diagnosed with breast cancer than a woman who receives HCT but not total body irradiation. A woman's age when she received HCT also affected breast cancer risk. Women who got HCT when they were 18 or younger were about 10 times more likely to be diagnosed with breast cancer later in life than women who were older when they got HCT.
If you've been treated for cancer, it's very important that you regularly see a doctor who is familiar with your past medical history, understands your special situation, and can give you the counseling, monitoring, and screening for possible complications of your earlier treatment. This suggestion is even more important if you were treated for childhood cancer or received total body irradiation and HCT as part of your earlier treatment. Based on your specific medical history, you and your doctor might want to consider more aggressive breast cancer screening. This might include more frequent mammograms starting earlier than age 40 or using different imaging techniques, such as breast MRI.