International Journal of Physical Medicine & Rehabilitation
Open Access

Radionuclide Therapy

Targeted radionuclide therapy (also called molecular radiotherapy) involves a radioactive drug called a radiopharmaceutical that targets cancer cells. Radiopharmaceuticals typically consist of a radioactive atom (also known as a radionuclide) combined with a cell-targeting molecule that seeks and destroys cancer cells. Some radionuclides have the ability to target specific cells on their own. 

When injected into the patient’s bloodstream, the radiopharmaceutical travels to and delivers radiation directly to or near disease sites. This treatment is known as ‘targeted’ radionuclide therapy because it damages cancer cells while limiting radiation exposure to healthy tissue. This type of therapy offers promise as a vehicle for personalized treatment of cancer because it can be tailored to the molecular properties of a specific tumor.

Targeted radionuclide therapy is currently used to treat certain cancers, including metastatic prostate cancer. However, researchers are developing and testing new targeted radionuclide therapies to treat a variety of other cancers.

Prostate cancer is the most commonly diagnosed cancer among men in the United States, other than skin cancer.  According to the American Cancer Society, approximately 238,000 new cases of prostate cancer are diagnosed and more than 29,000 men die from the disease annually in the United States. 

Imaging plays an important role in diagnosing and staging prostate cancer—as well as monitoring patients for recurrent disease (for more information on imaging, see the Molecular Imaging and Prostate Cancer Fact Sheet). Radionuclide therapies have long been used to alleviate pain in patients with metastatic prostate cancer—or cancer that has spread to the bone—and new therapeutic agents are under development as well. 

The prostate gland, located just below the bladder and in front of the rectum, is part of the male reproductive system. It is about the size of a walnut and surrounds the urethra (the tube that empties urine from the bladder). The prostate gland makes fluid that is part of the semen. 

Prostate cancer occurs when certain cells within the prostate gland grow in an uncontrolled, abnormal manner. Some tumors grow slowly while others grow at a more rapid pace. When localized, or confined to the prostate gland, prostate cancer may be cured.

Prostate cancer that spreads outside the prostate gland may initially grow into nearby tissues or lymph nodes. When prostate cancer spreads to distant sites within the body (or metastasizes), it most commonly involves the bones of the pelvis and spine. When the cancer spreads into the bone, it can cause pain, fractures and other complications that significantly impair a man’s health. Preventing or slowing the spread of prostate cancer to the bones is a major goal of treatment.

There are many treatment options for men with prostate cancer, including surgery to remove the prostate gland, radiation therapy, chemotherapy, hormonal therapy, and immunotherapy. Male sex hormones (called androgens) that circulate in the bloodstream can cause prostate cancer to grow. A common form of prostate cancer treatment reduces the level of androgens or blocks them from working. Despite such treatments, some prostate cancer continues to grow. This state is referred to as castrationresistant prostate cancer (CRPC). CRPC is often associated with cancers that have spread to the bone, called bone metastases. Treatment for men with CRPC is often aimed at controlling or relieving bone pain.