The incidence of breast cancer before 70 years in Icelandic women who carry a specific mutation in the BRCA2 gene increased fourfold between 1920 and 2002, according to a new study published in the Journal of the National Cancer Institute.

About 7% of Icelandic women diagnosed with breast cancer carry the specific BRCA2 mutation, including 24% of women diagnosed with breast cancer before the age of 40.

Laufey Tryggvadóttir, managing director of the Icelandic Cancer Registry in Reykjavik, and colleagues analyzed tissue samples from 847 patients diagnosed with breast cancer between 1921 and 1985 in Iceland. Eighty-eight patients carried the BRCA2 mutation. The authors found that the incidence of breast cancer in the mutation carriers increased from 19% to 72% between 1920 and 2002. A similar magnitude of increase was seen in relatives of the breast cancer patients who did not carry the mutation and in the general Icelandic population. In the same time period, the risk of death for BRCA2 mutation carriers increased from 13% to 27%.

The authors suggest that the main cause of the large increase in breast cancer incidence, both in carriers of the BRCA2 mutation and in women without the mutation, is likely related to changing lifestyle during the last several decades.

SOURCE:
Journal of the National Cancer Institute, January 18, 2006