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,
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.
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
Associations 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.