It is already known that relatives of very early onset breast cancer patients – without mutations in the BRCA1 and BRCA2 genes – carry a four-fold increased risk of the disease than those with no family link. However, a recent study [Dite, GS et al., Increased cancer risks for relatives of very early-onset breast cancer cases with and without BRCA1 and BRCA2 mutations, British Journal of Cancer (2010)] has found that both male and female relatives of women diagnosed with breast cancer before the age of 35 are at an increased risk of other cancers even if they do not carry faulty BRCA1 and BRCA2 genes.
The authors studied the 2200 parents and siblings of 500 women with breast cancer diagnosed before the age of 35 who had been tested for BRCA1 and BRCA2 gene mutations. After excluding families with mutations in BRCA1 and BRCA2, scientists found that the relatives not only faced an increased risk of breast cancer, but also of prostate, lung, brain and urinary cancers. This could potentially reflect the presence and effects of other undiscovered gene disorders causing disease in these young women and perhaps other cancers in their families.
In the 1990s, British research scientists were the first to map breast cancer gene, BRCA1 and BRCA2. Since then, many other genetic mutations have been discovered in a variety of cancers and cancer syndromes . Previous studies have suggested increased risks of other cancers for relatives of women diagnosed with breast cancer but the links have been weak and inconsistent. This study is one of the few to look at the cancer risks for relatives of very early onset breast cancer cases.