Cancers are primarily an environmental disease due to various factors like lifestyle, environment and genetics. Cancer therapies are currently limited to surgery, radiation, and chemotherapy. When tumors are treated with radiation alone, they shrink, but a large percentage of the cells left behind, which are cancer stem cells, could regrow the tumor.

Gold nanoparticles and quantum dots are used to diagnose cancer. Like other nanoparticles, quantum dots can be conjugated to antibodies, ligands or other targeting moieties to mediate specific interactions with cancer cells. Gold nanoparticles when irradiated with near-infrared light are capable of destroying tumors and particularly gold nanoshells are used to deliver little amount of heat to breast tumor cells already treated with radiation, boosting the destroying capacity of both therapies. The action is that, nanoshells increase perfusion of tumors with oxygen and also focally disrupts the blood supply to tumors, both of which enhance the effectiveness of radiation. Nanoshells reduce the population of stem cells dramatically which were left without destroying by radiation alone.

Nanoparticle constructs facilitate the delivery of various forms of energy for noninvasive thermal destruction of surgically inaccessible malignant tumors. Polymeric nanoparticles loaded with drug respond to the acidic pH inside tumor cells by expanding, releasing the anti cancer agent paclitaxel slowly over a long period of a day. They not only decreased tumor growth, but prevent new tumors from implanting themselves in the affected area.