Alpha radiation for bone metastasis
Cancer is a heterogeneous class of diseases characterized by cells displaying uncontrolled growth. Since the 1990s, cancer survival has been increasing in the United States. While this is certainly promising, the improvement in survival rates mainly stems from improved early detection and the subsequent treatment of the disease earlier in its progression. Our ability to treat metastatic cancer, however, remains poor. In 90 percent of patients with late-stage prostate cancer, the cancer will spread to the bone. Currently, there are no drug treatments that affect survival after prostate cancer spreads to the bone, but studies led by Dr. Chris Parker at London’s Royal Marsden Hospital appear promising.
Dr. Parker tested Alpharadin on patients with prostate cancer that metastasized to the bone. The results of this study showed an increase in survival from 11 months with chemotherapy plus placebo to 14 months for patients receiving chemotherapy plus Alpharadin. The results were so promising that the Independent Data Monitoring Committee stopped the trial and offered all patients enrolled in the study Alpharadin. Alpharadin is currently being developed by Bayer and has been given a US Food and Drug Administration fast track designation.
The current model in cancer progression is the Halstedian model. This model postulates that tumors grow locally, spread to the lymph nodes and then spread to the rest of the body. If this theory holds true, detecting cancer early and removing it will cure the cancer. Currently, cancer treatment primarily takes a “slash and burn” (surgery, radiation, chemotherapy) approach. The theory behind surgery is that you cut out the tumor before it metastasizes. After cancer has spread, however, complete removal via surgery becomes practically impossible. Radiation therapy works by ionizing radiation that damages genetic material of cells so they cannot function properly. Radiation kills all cells in the target area, including normal cells. Chemotherapy works by killing fast-dividing cells but cannot distinguish between abnormal fast-dividing cells (i.e., cancer cells) and normal fast-dividing cells (such as bone marrow, hair follicles and digestive tract cells). Furthermore, cancer stem cells are slow dividing. This means that chemotherapy does not target these cells, which can lead to relapse.
Since cancer is made up of one’s own cells, finding treatments that target only cancer cells has been difficult. Alpharadin’s active ingredient is radium-223. Radium-223 is an alpha particle. Alpha particles are much more damaging to cells then beta or gamma radiation, but they have a very small radiation range. Since radium sticks to bones, the radiation particle is optimally located to exert radiation on the cancer in the bones. Since alpha particles' radiation range is very small, this creates a very targeted treatment to the bones with minimal damage to surrounding tissues, including bone marrow.
Despite intense study of cancer, we are still limited in our ability to target cancer cells specifically over normal cells. New ideas for cancer treatments that specifically target cancer cells are continually emerging. Some treatments include things we normally consider quite harmful: viruses (http://www.patexia.com/blog/99). Others, such as Alpharadin, make use of radiation with small radiation range and an affinity for sticking to where the cancer is located.