A study found that people treated for cancer in childhood have a 10% risk of developing a different cancer -- including breast cancer -- later in life. The study was published in the Journal of Clinical Oncology.
In recent decades, some of the most important discoveries in cancer care have been in treating childhood cancer. Still, some childhood cancer patients develop a second cancer or another serious medical condition later in life that's believed to be related to the childhood cancer treatment. Doctors aren't exactly sure why childhood cancer survivors are more likely to be diagnosed with a different cancer later in life. For some, it could be their genetics that make them more likely to develop cancer at any time in life. But for many, the higher cancer risk is likely to be more directly related to the childhood cancer treatment. For example, radiation used to treat a childhood cancer also can affect normal cells exposed to the radiation, causing a new, different cancer that develops many years later.
The Childhood Cancer Survivor Study is a large, long-term study (longitudinal study) that's been following the health of 14,358 people from the time they were first diagnosed with cancer. All the people in the study were diagnosed with childhood cancer between 1970 and 1986, at an average age of about 8. They've been followed for about 18 years so far and are now in their 20s to 40s.
The most common childhood cancers diagnosed in the people in the study were:
- acute lymphoblastic leukemia (ALL), a cancer of certain white blood cells
- Hodgkin's disease (a cancer of the lymphatic system)
- kidney cancer
These types of cancer are more common in children than adults. More than 66% of the people in the study received radiation therapy as part of their childhood cancer treatment.
Overall, 9.6% of the childhood cancer survivors had been diagnosed with another cancer later in adulthood. Once a childhood cancer survivor was diagnosed with a cancer for the first time as an adult, they had a much greater risk of being diagnosed with a second or even a third cancer in adulthood:
- Nearly 3 of 10 childhood cancer survivors diagnosed with one cancer in adulthood and survived were later diagnosed with another different cancer.
- Nearly 4 of 10 childhood cancer survivors diagnosed twice with cancer in adulthood and survived were later diagnosed with a third different cancer.
Being diagnosed with two or more cancers in adulthood was most likely among survivors diagnosed with Hodgkin's lymphoma or a brain tumor in childhood.
The researchers found that childhood cancer survivors who got radiation therapy in childhood were much more likely to be diagnosed with a new cancer -- including breast cancer -- later in life compared to childhood cancer survivors who didn't get radiation therapy. There were 42 women in the study who got radiation therapy in childhood and were later diagnosed with multiple breast cancers.
The results of this study agree with the results of other studies showing that childhood cancer survivors are at much higher risk for a number of health problems in adulthood, including cancer. Because of these risks, people who have been treated for childhood cancer should be very aggressive about taking steps to minimize their risk of another cancer. These people also should have regular screenings for any complications of earlier treatment, including cancer. Still, a 2007 study found that childhood cancer survivors weren't getting the kind of medical care, counseling, and screening (including mammograms) that they should based on their medical history.
If you've been treated in the past for cancer, it's important to regularly see a doctor who:
- is familiar with your past medical history
- understands your special risks
- can give you the counseling, monitoring, and screening for possible complications of your earlier treatment
If your treatment history increases your risk of breast cancer, you and your doctor might want to consider a more aggressive breast cancer screening plan. This plan might include more frequent mammograms starting at an earlier age than the recommended 40, and perhaps using different imaging techniques, such as breast MRI.