WEDNESDAY, Oct. 8, 2003 (HealthDayNews) -- The effectiveness of radiation therapy for men with prostate cancer may be predicted as early as three months after they complete the treatment.
That's a huge improvement on the current one- to two-year wait, says a study by researchers at the University of Texas Health Science Center at San Antonio.
The study also found men whose blood PSA levels remained above important threshold levels three months after radiotherapy were 30 percent more likely to have a cancer recurrence than men who PSA levels sank to a lower level.
"Patients generally have their PSA tested soon after therapy, but unless there is a dramatic increase, many physicians wait a year or two and analyze the trend before interpreting the information. My colleagues and I disagree with that approach," lead author Dr. Sean X. Cavanaugh, a fourth-year radiation oncology resident, says in a prepared statement.
"We found that PSA levels at three or six months after radiotherapy were significantly prognostic for long-term outcome. Analysis of early PSA response enables us to accurately identify those patients who have an 80 percent or better chance of being cured of prostate cancer. Once confirmed by follow-up studies, this method may help us to identify men who will most benefit from the addition of hormone therapy, which has some serious side effects and should not be started in all men," Cavanaugh says.
He and his colleagues studied blood samples of 855 men treated with external beam radiotherapy. They compared the early PSA response of the men to their clinical outcome.
"At the three-month mark in this study, we established that if a patient's PSA level was lower than 3.0 ng/ml (nanograms per milliliter), his chance of long-term, relapse-free survival was 87.8 percent, compared to patients whose levels were above 3.0 at three months and who had only a 57.2 percent chance of relapse-free survival," Cavanaugh says.
The findings will presented Oct. 20 at the annual meeting of the American Society for Therapeutic Radiology and Oncology in Salt Lake City.
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