Pharmacogenetics may play a significant role in several aspects of breast cancer including prognosis at the time of diagnosis, response to specific treatments, and likelihood of adverse events to specific treatments. While a large amount of research has examined details of genetic predisposition to breast cancer, a relative paucity of work has been done to identify genetic variants that might predict a women's prognosis and response to treatment.

Once breast cancer is diagnosed, the most important is the response to treatment in order to achieve the better outcomes. Physicians do not have useful biomarkers that can help to identify women with a good benefit from a treatment, strong adverse effects, or suffer a recurrence, for instance.

So, it is very important to know genetic information from the tumor in order to decide the most successful treatment for each woman.

This special issue has the aim to contribute to the knowledge of biomarkers associated with the efficacy to a treatment, prognosis and survival of women with breast cancer disease.