No difference in the rates of biochemical failure was found between patients with stage T1 or T2 prostate cancer and a prostate-specific antigen (PSA) level of up to 10 ng/mL treated with radical prostatectomy and those treated with radiation therapy, stated Dr. Douglas Keyser of the Department of Radiation Oncology at the Cleveland Clinic Foundation in Ohio.
This finding is based on a large, single-institution experience with a relatively homogeneous population of 607 patients, with a median follow-up of 24 months. A total of 253 patients, with a median age of 70, underwent radiation therapy, and 354 patients, only 10% of whom were 70 years or older, underwent prostatectomy. All patients studied had to have pretreatment PSA levels of up to 10 ng/mL and clinical stage T1 or T2 disease. In addition, no patients received any type of adjuvant or neoadjuvant therapy.
The outcome based on pretreatment factors such as the stage of disease, Gleason score, and initial PSA level was analyzed. The clinical stage of disease had little impact on outcome regardless of the treatment. Patients with Gleason scores up to 6 fared about the same regardless of treatment; however, patients with Gleason scores higher than 7 seemed to fare better with radiation therapy than with surgery.
The pretreatment PSA level is still considered the most potent predictor of biochemical failure, according to Dr. Keyser. Based on the proceedings at the San Antonio Consensus Conference in the fall of 1996, a new definition of biochemical failure has been proposed: three consecutive rising PSA levels above the nadir value. Patients with PSA levels of up to 4 ng/mL did quite well regardless of the type of treatment; however, 30% to 40% of patients with PSA levels of 4 to 10 ng/mL experienced a biochemical failure. For the entire cohort of patients studied, the biochemical relapse-free survival was similar for both patients who underwent radiotherapy (75%) and patients who underwent prostatectomy (76%) at 5 years.