Radiation Effective in Treating Early Prostate Cancer, Large Study Confirms

Radiation therapy not only destroys prostate cancer in patients with early disease but keeps it from returning, a very large study of patients from six medical centers has found.

“The study confirms and elaborates on what has been reported before by individual medical centers: radiation therapy is an effective means to treat localized (stage T1B, T1C, or T2) tumors,” said lead author William U. Shipley, MD, of Massachusetts General Hospital, Harvard Medical School, in Boston, Massachusetts.

“The multicenter nature of this study shows that previous studies using smaller numbers of patients at individual medical centers can be widely generalized,” said Anthony Zietman, MD, also of Massachusetts General Hospital and Harvard Medical School.

Five-Year Follow-up Finds Patients Disease Free

All patients in the study received external-beam radiation therapy only and were followed after treatment with regular prostate-specific antigen (PSA) blood tests. The study found that 81% of patients who had a low pretreatment PSA level (less than 10 ng/mL) had no evidence of disease (ie, no consecutive rises in PSA levels) 5 years following radiation treatments. In addition, 68% of patients with a pretreatment PSA level higher than 10 ng/mL but lower than 20 ng/mL were disease free at 5-year follow-up.

“The follow-up of almost 450 patients for 5 years or more demonstrates the durability of success with radiation therapy,” said Dr. Shipley. Dr. Zietman added that the majority of patients were treated in the early 1990s, and that radiation therapy has improved substantially since that time. The results for patients treated in 1999 may be expected to be even better, he said.

Multicenter Trial

The study was conducted in patients from the University of Michigan Medical Center, Ann Arbor; Fox Chase Cancer Center, Philadelphia; Massachusetts General Hospital, Boston; Washington University, Mallinckrodt Institute of Radiology, St. Louis; Eastern Virginia Medical School, Norfolk, Virginia; and Stanford University Medical Center, Palo Alto, California.

The study was published in the Journal of the American Medical Association’s recent cancer outcomes issue. Data analysis was conducted by an independent biostatistical unit at M. D. Anderson Cancer Center in Houston, Texas. The study was supported by the American Society for Therapeutic Radiology and Oncology.