Modern radiation treatment makes extensive use of methods that deliver radiation to cancer cells not from a distance but by being inserted directly into or around the tumor . Radioactive sources can be injected, housed in special applicators or implanted in the form of needles or seeds.
Internal (Systemic) Radiation Therapy With this type of treatment, radioactive isotopes are given intravenously or placed in an organ such as the bladder or abdomen.
• One of the most common forms of systemic treatment involves the use of radioactive iodine (I-131), which is
sometimes used for carcinoma of the thyroid. Its use in thyroid cancer is limited because many thyroid cancers
fail to take up iodine. But if a thyroid cancer does show iodine uptake in preliminary tests, then by giving I-131
the isotope will be concentrated in the gland, thereby administering a high dosage of radiation to the organ while
sparing other tissues.
• At one time, radioactive phosphorus isotopes were placed within an abdominal cavity to treat malignant fluid
(ascites) or to prevent reaccumulation of that fluid. But its use today is quite limited.
• An agent called strontium 89 is currently used for treatment of bone metastases from prostate and breast cancer.
Given intravenously, this isotope shows promising preliminary results.
