She has genetic markers and a family history that predisposes her to certain types of cancer. In the case of breast cancer, she had an 87% chance of developing that type of cancer per Dr. Samadi on Fox. In the case of ovarian cancer her chance was 51%. With that information, her decisions seem reasonable.
Genetic markers are one thing. Environmental triggers are quite another in the expression of a gene, as cancer.
She could just as well optioned for anti-oxidant, immunogenic dietary and lifestyle changes and reduced those odds. Exception being the breast cancer potential.
The percentages would be better understood with clearer outlining of triggers for the markers. Like maybe microwave exposure, sun overexposure, fatty acid/esters in diet, free radical sinks/dietary. There is much more to be quantified for rational choices.