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Common inherited variant influences breast cancer risk after chest radiotherapy for survivors of childhood cancer

Posted on June 26, 2017

A selection of DNA samples for amplification at the Cancer Genomics Research Laboratory, part of the National Cancer Institute's Division of Cancer Epidemiology and Genetics (DCEG).

A selection of DNA samples for amplification at the DCEG Cancer Genomics Research Laboratory.

A common genetic variant is associated with higher risk of breast cancer among survivors of childhood cancer who received chest radiotherapy, according to a new study led by DCEG researchers. Childhood cancer survivors, particularly those who received radiation to the chest as part of their treatment, are known to be at elevated risk of developing breast cancer later in life. The researchers, led by Lindsay Morton, Ph.D., senior investigator in the Radiation Epidemiology Branch, conducted a genome-wide association study of nearly 3,000 female survivors of childhood cancer to identify whether inherited genetic susceptibility may influence which survivors go on to develop breast cancer. Using data from the Childhood Cancer Survivor Study and the St. Jude Lifetime Cohort, researchers pinpointed a single-nucleotide polymorphism (SNP) on chromosome 1q41 that increased breast cancer risk about two-fold per copy of the risk allele among patients treated with radiation to the chest. The variant did not appear to affect risk among survivors who did not receive chest radiotherapy.

The researchers also identified several additional regions with non-significant but promising associations with breast cancer in childhood cancer survivors. These findings, along with the significant variant at 1q41, should be investigated further in future studies. If confirmed, the authors hope that the results could be used to more precisely identify the risks and benefits of specific treatments for patients at the time of childhood cancer diagnosis. In addition, for patients who have already been treated, the results could be used to identify those with highest risk of developing breast cancer who might benefit most from increased screening.

Reference: Morton et al. Genome-wide association study to identify susceptibility loci that modify radiation-related risk for breast cancer after childhood cancer. JNCI. May 26, 2017