Due to decades of progress in childhood cancer diagnosis and treatment, most children not only survive the disease, but grow up to lead productive lives. However, research on the long-term effects of radiation therapy, chemotherapy, and other cancer treatments indicates that, over time, childhood cancer survivors are more likely than those in the general population to develop chronic health problems or second cancers.
Now a study led by Memorial Sloan Kettering biostatistician Chaya Moskowitz confirms that female childhood cancer survivors who were treated with radiation to the chest have a high risk of developing breast cancer at a young age – a risk that is comparable to that of women who have mutations in BRCA1 or BRCA2 genes. Mutations in these genes have been associated with a greatly increased risk for developing breast cancer before age 50.
“Previous studies have shown that women treated with radiation to the chest for childhood cancer have an increased risk for breast cancer, but ours is the first to demonstrate that their risk is comparable to women with BRCA mutations,” says Dr. Moskowitz, who presented the research at the 2012 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago in early June.
“While most women are aware that hereditary mutations can increase their risk for breast cancer, few are aware that radiation to the chest can also increase this risk, including the women who themselves were treated,” she adds.
Dr. Moskowitz and colleagues analyzed data from more than 1,200 female childhood cancer survivors participating in the Childhood Cancer Survivor Study, which involves survivors diagnosed with a childhood cancer between 1970 and 1986 at multiple institutions in the United States and Canada. Information was also drawn from 4,570 female first-degree relatives (mothers, sisters, and daughters) of women participating in the international Women's Environmental Cancer and Radiation Epidemiology (WECARE) Study.
The researchers found that 24 percent of women treated with chest radiation as children had developed breast cancer by the age of 50. By comparison, the disease occurred in 31 percent of women of the same age who carried a BRCA1 mutation.
Value of Long-Term Follow-Up Care
Memorial Sloan Kettering is a member of the Children’s Oncology Group (COG), a clinical trials consortium supported by the National Cancer Institute. The COG has developed guidelines for the screening and management of side effects appearing sometimes years after the treatment of childhood cancer survivors.
For females treated with doses of chest radiation amounting to 20 gray units (Gy) or more, the recommendation has been to initiate breast cancer surveillance with annual mammography and breast MRI, either beginning at age 25 or eight years after radiation therapy, whichever occurs later.
According to the recent findings, females treated with lower doses of chest radiation (10 to 19 Gy) are also more likely to develop breast cancer at a young age, and thus may also benefit from a breast cancer screening.
“Our findings underscore the importance of creating and adhering to a long-term follow-up plan for childhood cancer survivors,” adds Dr. Moskowitz. “Here at Memorial Sloan Kettering we are very fortunate to have a program in place to help transition our pediatric patients into adult survivors. There are very few institutions that offer this kind of continued care.”
Memorial Sloan Kettering established a Long-Term Follow-Up Program in 1990 to help survivors of pediatric cancers navigate and manage chronic medical conditions. In 2005, the Adult Long-Term Follow-Up Program was established to support childhood cancer survivors into their adult years. Both programs fall under the umbrella of the cancer survivorship program, a Memorial Sloan Kettering initiative to address the long-term consequences of cancer and its treatment.
In a June 4 USA TODAY story, ASCO President and pediatric oncologist Michael Link notes that the research findings reflect a growing sensitivity that for children with cancer, “cure is not enough.”