In fact, due to the increasingly systematic performance of genetic testing to detect mutations in genes that most commonly predispose to breast cancer (e.g., BRCA1, BRCA2, PTEN, P53, etc.), only 60 patients treated from 2001 to 2015 underwent such testing, simply because it was not widely applied during that period of time, mainly for cost–benefit reasons. This evidence concerns the gene PTEN and breast cancer.