mutations and SNPs as prognostic and predictive factors in patients with breast cancer.

Tumor protein 53 () is a tumor suppressor gene that encodes tumor protein p53. Tumor protein p53 regulates the expression of target genes in response to cellular stress. Additionally, p53 participates in the regulation of cell cycle checkpoints, DNA repair and apoptosis. Mutations in the gene are associated with numerous types of human cancer, including breast cancer, sarcomas, brain tumors and adrenal cortical carcinomas. In breast cancer, mutations are a negative prognostic factor. Tumors with mutations are more likely to be aggressive (triple-negative or human epidermal growth factor receptor 2-positive breast cancer), and resistant to chemotherapy and radiotherapy. In addition to a well-known mutation, a number of single nucleotide polymorphisms have been systematically identified and evaluated in human populations. In the present article, the role of mutations and polymorphisms in clinical practice and breast cancer treatment has been described. Additionally, the existing data on polymorphisms in breast cancer as prognostic and predictive factors have been summarized. A literature search of these topics was performed through PubMed and abstracts of the main cancer congresses in recent years.