Breast cancer (BC) is the second leading cause of mortality in females after lung malignant neoplasms. Dedicated, noninvasive diagnostic screening methods for early detection and surveillance (e.g., mammography/echography) have indeed increased the five-year relative survival rate of women with BC from 75% in the 1970s to 91% in the middle 2010s. Sadly, however, the same life expectation for BC patients diagnosed at late stages is still as low as 26%, the leading cause of related mortality being metastasis to lymph nodes, lung, liver, bone, and brain. Therefore, more efficacious BC treatments beyond the current standards of chemotherapy, radiation, and surgery - all of which may damage not only disease cells but also healthy tissuesdare heavily needed. Nanomedicine (NM) is a multidisciplinary arena aiming at the design, synthesis, characterization and application of materials and devices with nanoscale dimensions (1-100 nm). As a rapidly developing field, NM offers concrete opportunities in hu- man cancer theranostics since, contrarily to conventional drugs, nanobased platforms may be designed and tailored for, e.g., overcoming biological barriers, allowing for prolonged blood circulation time, simultaneously exploiting both active tumor targeting and enhanced permeability and retention (EPR) effects, efficient drug delivery, and reduced or eliminated side effects. Approximately 50 cancer NMs approved by the Food and Drug Administration (FDA) are available in the clinics [6,7] and, according to the National Institute of Health (NIH), 243 clinical trials involving NMs in cancer theranostics are currently ongoing. Of these NMs, this chapter will review those targeting BC, briefly discussing the advantages they offer and underlying the challenges this emerging trend in the medical field still must face in paving the road to fulfill the European Union “Beating cancer by 2030” promise.
