STANFORD, CalifAttempts to reduce prostate cancer mortality by ordering biopsies at ever-lower prostate-specific antigen (PSA) levels are driving up health care costs and subjecting thousands of men to early prostatectomies they could safely defer for years, according to researchers at Stanford University Medical Center.
Now, a large study has correlated serum PSA levels with subsequent quantitative histology of the cancer in radical prostatectomies at 1 ng/mL intervals of preoperative PSA. Thomas A. Stamey, MD, and his colleagues found that PSA levels between 2 and 9 ng/mL provide no reliable predictive information about prostate cancer and are principally the result of benign prostatic hypertrophy (BPH). This study was published in the Journal of Urology (167:103-111, 2002).
The purpose of the study was to determine whether preoperative PSA levels correlated with any of a number of morphological variables known to affect cure rates from radical prostatectomy.
"We are overdiagnosing prostate cancer at a huge rate," said Dr. Stamey, professor of urology, Stanford University. He suggests that physicians may wish to avoid biopsy at PSA levels lower than 4 ng/mL. He thinks that biopsy can be delayed safely for a few years to confirm a PSA rise from 4 ng/mL into the 7 ng/mL range, and that prostatectomy can be delayed for years in men whose PSA is in the 2 to 4 ng/mL range and whose prostate is larger than 30 g.
Prostate cancer is a ubiquitous cancer of aging that starts in the 20s and increases in prevalence in every decade, from 8% in men age 20 to 30 to 80% in those age 70 to 80, Dr. Stamey said. "If you look for cancer with enough biopsies in men over age 50, you will often find it. However, few men die of the disease," he said. The SEER data show that the annual prostate cancer death rate in men over age 65 is 0.23% (226/100,000).
"We all thought there was a relationship between a PSA of 2 to 9 ng/mL and prostate cancer, but there is not. The cancers detected in biopsies of men at those levels is due to serendipity," he said.
Since 1983, Dr. Stamey and pathologist John E. McNeal, MD, have sectioned every prostate removed at Stanford into 3 mm step sections and quantified the percent of Gleason grade 4 or 5 tumors, volume of grade 4 or 5 tumors, volume of the largest tumor, percent of tumors smaller than 0.5 mL, percent with capsular penetration, percent with positive surgical margins, percent with positive lymph nodes, percent with positive seminal vesicles, percent with cancer confined to the organ, percent with transitional zone involvement, prostate weight, patient age, and percent of tumors that were stage T1c-T2c.