To say that some women are predisposed to breast cancer is not a totally accurate statement. Although a woman with a BRCA1 or BRCA2 is statistically more likely to develop breast cancer than a woman without this genetic alteration, not every woman with an altered BRCA1 or BRCA2 will get breast cancer.
Remember, genetics is just one of many known risk factors. An altered gene such as BRCA1 or BRCA2 does not guarantee breast cancer.
In fact, most cases of breast cancer do not involve an altered BRCA1 or BRCA2 gene. Statistics show that at most, 1 in 10 breast cancers cases involve an inherited altered gene. Furthermore, not all cases of breast cancer in patients with a family history of breast cancer involve genetic alterations in BRCA1 or BRCA2.