Women who carry one mutated copy of the ATM gene have twice the risk of developing breast cancer during their lifetime and almost five times the risk of developing breast cancer before age 50 compared with the general population, according to a new study.

Mutations in both of the ATM gene are responsible for ataxia telangiectasia (A-T), a rare autosomal recessive neurologic disorder. A-T patients have a higher risk of developing childhood lymphoid leukemias and lymphomas in addition to epithelial tumors later in life. Studies have also indicated that individuals who carry one mutated copy of the ATM gene (i.e., heterozygous mutation carriers) may have a higher risk of breast cancer and perhaps other cancers, but the precise risk is uncertain.

To determine the risk of cancer among heterozygous ATM mutation carriers, Douglas F. Easton, Ph.D., of Cambridge University in England, and colleagues obtained cancer incidence and mortality information for 1,160 relatives of 169 British A-T patients.

Female ATM mutation carriers had twice the risk of breast cancer overall compared with the general population. This is equivalent of a lifetime risk of breast cancer of one in six among mutation carriers compared with one in 11 in the general population of England and Wales. Among women younger than age 50, mutation carriers had five times the risk of breast cancer as the general population.

The estimated risk of cancer before age 80 was only slightly greater among male ATM mutation carriers than in the general male population (39% versus 36%), but this risk was much greater among female ATM mutation carriers than in the general female population (35% versus 21%). There was also some evidence of an increased risk of colorectal cancer and stomach cancer among ATM mutation carriers. Contact: Nick Stewart, Cancer Research UK, (44) 20 7061 8317,

Contact: Sarah L. Zielinski
jncimedia@oupjournals.org
301-841-1287
Journal of the National Cancer Institute
31-May-2005