A study of 10,873 MBC cases from the National Cancer Data Base in the US showed that older age, black race, higher Charlson comorbidity index, higher tumor grade and stage, and receipt of total mastectomy were associated with poorer OS, while residing in a high income area, positive PR expression and administration of chemotherapy, radiation or endocrine therapy were associated with better OS (22). This evidence concerns the gene PGR and neoplasm.