HIGHER DOSE RADIATION BETTER FOR PROSTATE CANCER

NEW YORK (Reuters Health) Feb 17 - For early-stage prostate adenocarcinoma, high-dose conformal radiation appears to achieve better results than conventional doses, researchers report in a February 1st on-line paper in the Journal of Clinical Oncology.

"The long-term data from this study confirm that higher doses of radiation are more likely to durably eradicate localized prostate cancer than more conventional doses," lead author Dr. Anthony L. Zietman told Reuters Health by email. "As proton beam was used in this study, it also confirms that proton beam is one excellent way to deliver these more effective, higher doses."

Dr. Zietman of the Massachusetts General Hospital, Boston, and colleagues came to this conclusion after randomizing 393 men to receive a total dose of either 70.2 or 79.2 Gray equivalents.

After a mean follow-up of 7.9 years, men in the high-dose group were significantly less likely to experience local failure (hazard ratio, 0.57).

In the 227 patients with low-risk disease, the 10-year American Society for Therapeutic Radiology and Oncology biochemical failure rates were 7.1% in the high-dose group and 28.2% in the conventional dose group. There was also a strong trend in the 144 intermediate risk patients (30.4% versus 42.1%).

Initially, none of the patients had androgen suppression therapy. Later, however, 6% of high-dose patients and 11% in the conventional-dose group required androgen deprivation for local recurrence.

Despite the apparent success of the approach, Dr. Zietman pointed out that the study does not "answer the question of whether or not proton beam is a superior technique when compared with the alternatives such as intensity modulated radiation therapy or brachytherapy."

Also, the paper points out, there was no difference between the groups in overall survival (78.4% with high-dose therapy and 83.4% in the conventional dose group).

In an accompanying editorial, Dr. W. Robert Lee of Duke University Medical Center, Durham, North Carolina, highlights the lack of improvement in overall survival and points out that given the alternative of active surveillance, radiation therapy may not always be the best approach.

"In fact," he concludes, "for the 73-year-old man with low-risk prostate cancer, the best dose may be 0 Gy."

J Clin Oncol 2010.