As an example, in a combined series of women aged 55 years or older with breast cancer derived from the San Antonio Breast Cancer Database (n = 35,154) and the Surveillance, Epidemiology, and End Results (SEER) registry (n = 171,424), breast cancer diagnosed in elderly women had lower proliferative indices, normal p53 expression, and diploid DNA, compared with breast cancer diagnosed in younger women [17]. This evidence concerns the gene TP53 and breast cancer.