Outcomes Measured In Relation To Radical Prostectomy, External Beam Radiation, And Seen Implant Therapy
Philadelphia, PA--Implanting radioactive-filled seeds into a cancerous prostate gland has been a largely sucessful method of treating the second-leading cancer killer among men for more than two decades. However, a new study says that, after an estimated 41-month follow-up, patients classified as high-risk had a poorer outcome after being treated with the seed implant therapy compared to those who underwent either radical prostectomy or external beam radiation. These findings are published in the September 16, 1998 issue of the Journal of the American Medical Association (JAMA). The study also concluded that no significant difference in outcome was noted in low risk patients across all treatment modalities for this short and limited follow-up period.
"These results suggest that a particular population of patients -- those we can pre-therapeutically determine to be "high risk" -- don't do as well with the seed therapy as judged by prostate specific antigen (PSA) levels, as with alternative forms of therapy," says Alan Wein, MD, senior investigator on the study and chief of urology at the University of Pennsylvania Cancer Center.
Penn researchers used collected data from 1,872 men who were treated for their localized prostate cancer between 1989 and 1997. The men underwent one of three treatment options: radical prostectomy, external beam radiation, or seed implant therapy offered at two clinical sites.
The researchers set out to measure the rate of disease-free survival for these patients. In doing so, they used three tests: PSA, biopsy Gleason score, and the American Joint Commission on Cancer staging (AJCC) T-stage.
As background, PSA blood tests measure the level of prstate-specific antigens in the blood: the results are reported as nanograms per milliliter, or ng/ml. The higher the PSA level, the more likely that cancer is present. The Gleason score rates the aggressiveness of a tumor; from a low score of 2 to a high score of 10. Finally, a T-stage test determines a tumor's actual growth and potential for further growth.
Retrospectively, the men in the study were categorized into one of three risk groups -- low, intermediate, and high -- according to the combined results of their PSA levels, Gleason scores, and AJCC T-stages.
The study showed a clear realtionship between a recurrence of cancer in "high-risk" patients who had opted for seed implant therapy five years earlier. "Although this is only a short follow-up in the natural history of prostate cancer, it clearly indicates that patients who are classified as high-risk should talk to their physicians about an alternative form of treatment," Dr. Wein says.
"Penn has been one of the nation's pioneering institutions offering men various types of therapies for their prostate cancer, including seed implants. We regard this therapy as a succesful treatment option for some patients, but this new information suggests that physicians use caution when selecting patients for seed therapy," concludes Dr. Wein.
Editor's Note: This study was conducted in conjunction with principal investigator, Anthony D'Amico, MD, at Brigham & Women's Hospital in Boston. Dr. Wein can be reached for comment at (215) 662-6755.
Journal
JAMA