*3.7. Bone Cancer Therapy*

Cancer is the uncontrolled growth of tissues that could lead to invasion into other organs without proper regulation or differentiation [580]. Conventional cancer therapy is associated with multiple adverse side effects [581]. Bone metastases or "bone mets" occur when cancer cells from the primary tumor relocate to the bone and also spread in the prostate, breast, and lung, which leads to painful (75% of patients) and devastating skeletal-related events (SREs) [582,583]. Depending on the stage of the disease, history, and the overall health of the patient, disease management includes a combination of therapies as shown in Figure 29 [584].

**Figure 29.** Bone metastasis management through combination of therapies.

The different types of nanoparticles (NPs) used as carriers for small-molecule drugs, proteins, and nucleic acids [585] can be localized to specific disease locations for the treatment of bone metastasis [586]. Nanoparticles also improve the efficiency of other methods used for treating bone metastasis [587]. The effectiveness of NPs depends on their accumulation in vascularized solid tumors via the enhanced permeability and retention (EPR) effect [588]. A wide variety of nanomaterials have been developed in the 1 to 100 nm range and include various anti-tumor drugs (Figure 30) by fine-tuning the chemical structure, scale, and shape (morphology) that can regulate the nanomaterials' functionality [589].

**Figure 30.** Schematic representation of different types of nanomaterials and their drug-loaded conjugates employed in cancer therapy. (Adapted with permission from ©2019 Springer [589]).
