Childhood cancer survivors show inadequate screening for breast cancer

Even though women treated for childhood cancers with chest radiation suffer a high risk of breast cancer, they are far less likely to begin recommended early mammogram screening than they should, researchers at St. Jude have found.

The findings of the first-ever survey of such at-risk women emphasise the importance of educating them and their physicians about the need for early screening, said Les Robison, PhD, Epidemiology and Cancer Control chair. The researchers published their findings in the Journal of the American Medical Association.

“Over the last decade, the Childhood Cancer Survivor Study (CCSS), a consortium of 26 centres in the United States and Canada, led by the research team at St. Jude, has developed strong evidence that female childhood cancer survivors with radiation exposure to the chest constitute one of the highest risk populations for breast cancer,” said Robison, the paper’s senior author. “Their risk is even higher than that of women with mutations in the cancer genes BRCA1 and BRCA2. Thus, it is currently recommended that these women begin screening for breast cancer at age 25, with the objective to catch the disease at an early stage, making successful treatment far more likely.”

To discover whether such at-risk women were having early screening, the researchers surveyed a sample of 551 female participants in the CCSS. The women, who had been treated for childhood cancers with chest radiation, were between 25 and 50 years old.

The survey revealed that only 55 percent of the women reported having a screening mammogram in the previous two years. Although low, this percentage was higher than comparison groups of women with childhood cancers who had not received chest radiation (40 percent) and siblings with no cancer (37 percent), the researchers found.

The screening level was particularly low among women ages 25 to 39, with only 36.5 percent reporting having mammograms in the previous two years. By contrast, 76.5 percent of the women ages 40 to 50 reported having mammograms. Nearly half of the women younger than 40 had never had a mammogram, Robison said.

“These statistics document a serious problem – that a large proportion of women who should be screened at a very young age are not being tested,” he said.

The survey documented that physician recommendations were most likely to influence the women to have mammograms. Women who had a positive view of screening mammography were also more likely to have mammograms.

One important component of this positive view is the understanding of the low risk due to radiation from mammograms. For women treated with radiation for their childhood cancers, the additional risk of the relatively tiny dose of radiation received in a mammogram is trivial, Robison said.

“These insights into the factors underlying the decision to have mammograms tell us that we have to educate these survivors as well as the health care community about the risks,” he said.

A major problem the researchers noted is that such at-risk women are rare in the general clinical population – even though there are between 20,000 and 25,000 women 25 years and older in the US who were treated for childhood cancers with chest radiation.

“Any single practice is unlikely to see more than a couple of these survivors,” Robison said. “Unless the patient tells the physician that she had chest radiation for childhood cancer and is at a high breast cancer risk, that fact might never come out.”

Thus, Robison said, besides continuing to monitor the mammogram frequency among the at-risk women, the CCSS consortium will begin to develop educational programs for these women and health care providers.

“We would hope that these programs could achieve the ultimate goal of bringing the screening rate of this at-risk population to 100 percent,” Robison said.

(Source: St. Jude Children’s Research Hospital: Journal of the American Medical Association: March 2009)