About one in eight women will develop invasive breast cancer over the course of her lifetime. Causes can be the use of synthetic sex hormones and other environmental factors, but also gene mutations like in the BRCA1 gene (BReast CAncer). US actress Angelina Jolie who underwent a preventive double mastectomy is the most famous carrier of a „faulty“ BRCA1 gene. On average, women with this mutation have an up to 87% lifetime risk of developing breast cancer. Tumors usually develop early in life. Until now, prophylactic surgery is the only procedure which significantly reduces the breast cancer risk, but which is also often associated with postoperative complications. (Mehr in: Cancer News — ScienceDaily)
Tomasetti and Vogelstein show that the lifetime risk of cancers of many different types is strongly correlated with the total number of divisions of the normal self-renewing cells maintaining that tissue’s homeostasis. These results suggest that only a third of the variation in cancer risk among tissues is attributable to environmental factors or inherited predispositions. The majority is due to bad luck, that is, random mutations arising during DNA replication in normal, noncancerous stem cells.
Tomasetti C, Vogelstein B (2015): Variation in cancer risk among tissues can be explained by the number of stem cell divisions. Science 2 January 2015: Vol. 347 no. 6217 pp. 78-81 DOI: 10.1126/science.1260825