Final answer:
The treatment directed toward the secondary site is usually aimed at metastatic cancer and can include focused radiation therapy such as brachytherapy or proton beam therapy, specifically targeting the secondary tumors.
Step-by-step explanation:
The treatment that is directed toward the secondary site only refers to therapeutic approaches that target metastatic cancer, which is cancer that has spread to a location distant from the primary site. When surgery or other treatments have been used on the primary tumor but cancer cells have spread and formed new tumors elsewhere, treatments such as focused radiation therapy or systemic therapies may be used to address these secondary sites. For instance, brachytherapy, which involves placing radioactive sources near the cancerous tissue, and external radiation therapy, such as proton beam therapy, can be employed to target secondary tumors with precision to minimize damage to surrounding healthy tissue.