Radiation Helps Prostate Cancer Patients Live Longer, Study Shows

Doctors have suspected that radiation therapy helps prevent patients from dying of prostate cancer, but they had little scientific evidence to support that theory. Now, Richard Valicenti, MD, assistant professor of radiation oncology at Jefferson Medical College of Thomas Jefferson University in Philadelphia and his colleagues have confirmed that radiation therapy helps patients with localized prostate cancer live longer. Dr. Valicenti presented these findings at the 1999 meeting of the American Society of Clinical Oncology (ASCO).

The researchers retrospectively examined the results of radiation therapy in 1,560 prostate cancer patients. The patients were among those treated in four separate trials conducted by the Radiation Therapy Oncology Group between 1975 and 1995. The average follow-up was 8 years, with some patients monitored for as long as 12 years.

Patients With Worst Prognosis Benefit Most From Higher Radiation Doses

After dividing the men into four categories according to their likelihood of having more serious disease, Dr. Valicenti and colleagues found that those with the worst prognosis benefited the most from higher doses of radiation. After the investigators statistically adjusted their data for disease severity and patient age, they found that patients who received higher-than-usual radiation doses were 32% less likely to die of prostate cancer.

“I think these results will change how we evaluate the use of higher radiation doses and new radiation treatment systems for prostate cancer,” said Dr. Valicenti.

Dr. Valicenti and his coworkers at Jefferson, Wayne State University in Detroit, the University of Southern California, McAuley Health Center in Ann Arbor, Michigan, and Einstein Medical Center in Philadelphia evaluated the Gleason scores and radiation doses of patients in four separate studies. They found that overall, patients with the highest Gleason scores (between 8 and 10, on a scale of 2 to 10), who should have had the worst prognoses but who received higher radiation doses, had better local control of their cancer and were more likely to be disease-free and alive longer.

“Radiation therapy provides an overall survival benefit for clinically localized prostate cancer for those with a Gleason score between 8 and 10,” said Dr. Valicenti. “Those less than 8 didn’t experience an observable advantage with follow-up to 12 years.”

“We were happy to see improvement of local control with higher radiation doses,” he said. “This would suggest in part that the disease-free survival advantage is attributed to improved tumor control.”

The work was funded, in part, by the National Cancer Institute.