Survival is bleak for prostate cancer patients with advanced tumors that have spread to the bone, but a radioisotope procedure being evaluated in a clinical trial is extending lives by several months, according to a study presented at the Society of Nuclear Medicine (SNM) annual meeting, being held in Miami Beach, FL, this week.
Castration-resistant prostate cancer is a late-stage form of cancer typically characterized by extensive treatment-resistant skeletal metastases. Men with castration-resistant prostate cancer generally live three to five years after diagnosis. In the U.S. alone, more than 28,000 men are expected to die from this disease in 2012, according to estimates from the U.S. National Cancer Institute (NCI). The NCI also estimates that 241,740 new cases of prostate cancer of various levels of severity will be diagnosed in 2012.
The phase III study is evaluating radioisotope therapy with radium-233 (Ra-233) chloride. Ra-233 has very potent alpha particles that seek out bone metastases, but the short range of penetration spares nearby healthy tissues and bone marrow.
The double-blind, placebo-controlled, randomized study included 921 men. The therapy was administered in six injections at four-week intervals. Patients who received Ra-233 lived a median of 90 days longer than those who received the placebo, reported Dr. Val Lewington, a professor of clinical therapeutic nuclear medicine at King's College and Guy's and St. Thomas' Hospital in London.
In addition to prolonged survival, patients treated with Ra-233 experienced statistically significant delays in the onset of complications caused by bone metastases. Disease progress was followed using scintigraphy and PET imaging.
An expanded access program is already under way in the U.S., and a similar program is expected to open in Europe in 2012. Further clinical trials also are being considered. Formal regulatory approval for Ra-233 will be sought in mid-2012 in both the U.S. and Europe.
