Aug 18, 2010
Girls who undergo chest radiation as a cancer treatment are significantly more likely to develop breast cancer as little as eight years later, according to a study conducted by researchers from Memorial Sloan-Kettering Cancer Center in New York and published in the Annals of Internal Medicine.
“Risk in women treated before puberty is not lower than that in those treated during adolescence, as suggested by some early studies,” they wrote.
The researchers reviewed the results of 12 prior studies  that had looked at breast cancer  risk in female survivors of childhood cancers. They found that patients who have undergone chest radiation as children suffer from an increased risk of breast cancer  as little as eight years later.
“This incidence is similar to that in women  with a BRCA gene mutation,” the researchers wrote.
The risk  does not plateau over time but only continues to increase, so that by age 40 or 45 as many as one in five childhood cancer  survivors has contracted breast cancer. The more radiation a woman was exposed to as a child, the higher her cancer risk .
- A d v e r t i s e m e n t
The Children’s Oncology Group, of which the researchers are a part, recommends that because of this risk, female survivors of childhood cancers get annual mammograms  starting at age 25, or eight years after the end of their radiation therapy — whichever comes later.
Yet the researchers cautioned that more research  is needed before this can be emphatically recommended, since mammograms also expose women to radiation and can increase their cancer risk. A woman who begins getting yearly mammograms at age 25 would end up getting 15 more mammograms in her lifetime than a woman who began at age 40.
In addition, it is unknown if cancer survivors  react differently to radiation than other women do.
Due to concern over false positives and radiation risk, the U.S. Preventive Services Task Force no longer recommends annual mammograms. It recommends biannual tests for women over the age of 49.