PALM BEACH, Fla--A urologist believes his unique viewpoint can be helpful to radiation oncologists doing brachy-therapy and to his fellow urologists. "By 2005," said Nelson Stone, MD, of Mt. Sinai Medical Center, NY, "projections indicate that two thirds of prostate cancer cases will be treated with brachyther-apy or external beam irradiation. If urologists don't get on board, they'll be treating half of the cases they are now."
By looking at radical prostatectomy data and comparing the pathological results with pretreatment PSA levels, urologists can help improve patient selection for brachytherapy, Dr. Stone said.
"Prognostic variables help determine whether patients should have radical prostatectomy alone; seed implant plus external beam radiation; hormonal treatment plus seed implant; or some other combination of the various therapies," Dr. Stone said at the 19th annual meeting of the American Brachytherapy Society (ABS).
By evaluating prognostic data, Dr. Stone and his colleagues at Mt. Sinai have come up with treatment guidelines for use of brachytherapy and/or combined modalities in prostate cancer (see table ).
Dr. Stone feels that seminal vesicle biopsy and even lymph node dissection may be important in determining whether a patient needs monotherapy or a combined therapy.
A number of years ago, Dr. Stone said, he began investigating whether seminal vesicle involvement could be detected by doing a simple prostate needle biopsy of the seminal vesicles in addition to the prostate biopsy.
Being able to determine seminal vesicle involvement allows the physician to change therapies up front if needed. The physician can tell the patient who has positive seminal vesicles that with radical prostatectomy alone, he will have a 75% chance of biochemical failure down the road. "This allows the patient to participate in deciding the best treatment," Dr. Stone said.
His selection criteria for performing seminal vesicle biopsy are PSA above 10 ng/mL, Gleason grade of 4 or 5, and stage T2b disease or higher. "This gives a one in five chance of diagnosing cancer in the seminal vesicles," he said.
Dr. Stone emphasized that urologists and radiation oncologists must work together on this. If a patient with the above scores is referred to the oncologist without having had a seminal vesicle biopsy, the patient should be referred back to have one done, since this information is needed to help determine the applicability of brachytherapy.
Lymph Node Dissection
Using the Partin-Walsh nomogram, a patient with a Gleason score of 7, PSA of 11, and stage T2b prostate cancer would have a 33% likelihood of positive seminal vesicles and a 24% likelihood of positive lymph node involvement. If the seminal vesicle biopsy shows positivity, the chance that the lymph nodes are involved increases to 38%.
"If we do a multiple regression analysis using these four factors, we find that seminal vesicle biopsy is the most important predictor of lymph node disease. Gleason scores, PSA, and staging almost dropped out as being important predictors," he said.
Laparoscopic lymph node dissection has little or no associated morbidity, Dr. Stone said, and it should not be ruled out "just because we're not operating on the patient."