Contributions of nanotechnology to the intraductal drug delivery for local treatment and prevention of breast cancer.

Breast cancer is a major public health problem, affecting millions of people. It is a very heterogeneous disease, with localized and invasive forms, and treatment generally consists of a combination of surgery and radiotherapy followed by administration of estrogen receptor modulators or aromatase inhibitors. Given its heterogeneity, management strategies that take into consideration the type of disease and biological markers and can provide more personalized and local treatment are required. More recently, the intraductal administration (i.e., into the breast ducts) of drugs has attracted significant attention due to its ability of providing drug distribution through the ductal tree in a minimally invasive manner. Although promising, intraductal administration is not trivial, and difficulties in duct identification and cannulation are important challenges to the further development of this route. New drug delivery strategies such as nanostructured systems can help to achieve the full benefits of the route due to the possibility of prolonging tissue retention, improving targeting and selectivity, increasing cytotoxicity and reducing the frequency of administration. This review aims at discussing the potential benefits and challenges of intraductal administration, focusing on the design and use of nanocarriers as innovative and feasible strategies for local breast cancer therapy and prevention.