More than ninety percent of men who receive appropriate radiation doses with permanent radiation seed implants to treat prostate cancer are cured eight years after diagnosis, according to an article in the February 1 issue of the International Journal for Radiation Oncology*Biology*Physics.

Seed implants have become a widely accepted treatment option for early-stage prostate cancer because it is very effective, is minimally invasive, and often spares patients from side effects of other treatments, such as impotence and incontinence.

In the current study US researchers evaluated long-term results of permanent seed implants in men with early-stage prostate cancer. Nearly 2,700 men were studied at 11 institutions in the United States over eight years. The radioactive seeds were administered with the aid of ultrasound-guided techniques to accurately place the seeds in the prostate gland. The patients received seed implants as sole treatment for prostate cancer with no additional chemotherapy or radiation therapy.

Data analysis showed that 93 percent of men who received -130 Gy to 90 percent of the prostate (D90) were disease free at eight years.

The authors concluded that outcome for this patient population relates to tumor stage (study was limited to T1-T2), Gleason score, pretreatment prostate specific antigen year, year of seed insertion, and post-brachytherapy dosimetric quality.
A post-treatment low level for prostate specific antigen of 0.5 ng/mL or less was particularly associated with durable long-term disease-free survival. The only controllable factor to affect long-term outcome was the D90, a reflection of implant quality.

“This study is exciting because it shows that brachytherapy alone without additional surgery, radiation or drugs can be effective at curing early-stage prostate cancer,” said Michael J. Zelefsky, M.D., lead author of the study and Chief of Brachytherapy Services at Memorial Sloan-Kettering Cancer Center in New York. “These results also confirm other findings that the quality of the seed implant is a critical ingredient for achieving a better outcome.”

Medical centers participating in the study were Memorial Sloan-Kettering Cancer in New York, M.D. Anderson Cancer Center in Houston, New York Prostate Institute in Oceanside, N.Y., Arizona Oncology Services in Scottsdale, Ariz., Seattle Prostate Institute in Seattle, Chicago Prostate Institute in Chicago, Cleveland Clinic Foundation in Cleveland, Massachusetts General Hospital in Boston, Mayo Clinic in Rochester, Minn., University of Michigan Medical School in Ann Arbor, Mich., and Fox Chase Cancer Center in Philadelphia.