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Your Health This WeekPromising new treatments for cancer and osteoporosis.

By Sydney Spiesel
Posted Tuesday, May 22, 2007, at 12:28 PM ET
Bexxar. Click image to expand.

This week, Dr. Sydney Spiesel discusses two promising new treatments: one for cancer and another for osteoporosis.

The benefits of radioimmunotherapy

Concept: Radioimmunotherapy is an exciting but elusive new treatment for cancer. The idea is clever: Make tightly targeted antibodies that can bind to specific sites on the surface of tumor cells. Then bind intensely radioactive material to these antibodies. Injected into a patient, the radioactive antibody molecules home in and attach to the targeted sites, and destroy the malignant cells by spraying them (and other nearby tumor cells) with lethal radiation.

Treatments: Two such radioactive-antibody cancer medications exist: Bexxar and Zevalin. As the drug Rituxan, which consists of the antibody without the radioactivity, they are already widely used for non-Hodgkin's lymphoma and other cancers. With the radioactivity, Bexxar and Zevalin can be used to treat patients with lymphoma even if they have developed resistance to Rituxan. Similar products (made with different monoclonal antibodies) have shown promise for the treatment of brain cancer, breast cancer, and lung cancer.

Effects: Bexxar and Zevalin cost approximately the same—a staggering $25,000 to $30,000 for the roughly weeklong treatment. Both have worked for some patients, apparently leading to long-term remissions. Both also can cause dangerous, even lethal, reactions and side effects, though that is rare.

Comparison: The two treatments have not been tested head-to-head, so we have no idea of their comparative effectiveness, but we know of some differences between the two products. The body clears the radioactivity of Bexxar more quickly than that of Zevalin. On the other hand, Bexxar's radioactivity has the potential for harming the thyroid gland and may even pose risks to people in close contact with the patient shortly after the drug is administered. Also, patients are more likely to develop an allergic reaction to it. Zevalin, however, must be made up by a specially trained radio-pharmacist, working near the location where the medicine will be administered, because the half-life of its radioactive isotope is short.

Problem: This promising line of treatment is underutilized. One reason is simple unfamiliarity. Another is patients' general fear of radioactive materials. And a third reason is lack of training among oncologists, the doctors who work daily with patients with tumors, in the use of radioactive materials. In general, this kind of work is done by specialists in nuclear medicine. We need to train more oncologists in this method.

Strengthening weak bones

Condition: Osteoporosis is a medical condition in which the bones lose some of their calcium and weaken as a result. An estimated 24 million people in the United States (and well over 250 million worldwide) suffer from this condition. The great majority are women over the age of 45. The bone weakness caused by osteoporosis increases the risk of fractures. The cost of these broken bones is high: more than $18 billion a year just for medical costs in the United States.

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Sydney Spiesel is a pediatrician in Woodbridge, Conn., and clinical professor of pediatrics at Yale University's School of Medicine.
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