Oct 5 2004
Increasing the radiation dose delivered by highly conformal external beam radiation to men suffering from early stage prostate cancer shows an advantage in terms of increased disease-free survival rates, according to a study presented October 5, 2004 at the American Society for Therapeutic Radiology and Oncology’s 46th Annual Meeting in Atlanta.
For two decades, external beam radiation therapy has been one of the standard methods for treating prostate cancer. In the past, radiation oncologists have been limited in terms of the dose they could deliver to the affected area for fear of inducing serious bladder or rectal side effects. In recent years, however, external radiation has become much more accurate and the delivery of higher doses of radiation have become a real possibility.
Investigators from Massachusetts General Hospital, Harvard Medical School and the Loma Linda University School of Medicine completed a study designed to determine whether or not a highly conformal technique employing the proton beam would allow the safe delivery of high radiation doses and whether or not the higher radiation doses would make a difference in the treatment of early stage prostate cancer.
Three hundred and ninety three men with early stage prostate cancer were randomized to receive either conventional dose or high-dose radiation therapy. Regardless of the dosage, all of the patients were treated with the more accurate conformal radiation that included the use of a proton beam. The five-year disease-free survival rate for those who received high-dose radiation therapy was promising – with only 17 percent showing evidence of recurrence of their cancer. Thirty-five percent of the patients who received the conventional dose experienced recurrence of cancer.
The level of rectal and bladder side effects was equally low – less than 2 percent experienced serious problems – whether the patients were treated with conventional dose or high-dose radiation.
“Though the results from conventional dose external beam radiation therapy have been satisfactory, there has always been hope that the cancer could be more reliably eradicated by the use of higher and more aggressive doses of radiation,” said Anthony L. Zietman, M.D., a radiation oncologist at Massachusetts General Hospital in Boston and lead author of the study. “This study suggests that radiation oncologists can and should be more aggressive in their treatment of prostate cancer provided they have sophisticated dose delivery techniques such as proton beam at their disposal.”