February 1, 1994
Media Contact: Joann Rodgers
Phone: (410) 955-8659
Researchers at The Johns Hopkins Medical Institutions have developed new
guidelines for identifying those men with non-palpable prostate cancers who can be managed
through "watchful waiting" (semi-annual checkups) rather than by surgery or radiation treatment.
Non-palpable cancers cannot be detected by the doctor during rectal
The guidelines should help to reduce a current controversy among surgeons over which men can be followed safely without initial treatment rather than subjected to radical prostatectomy (surgical removal of the prostate) or radiation, according to Jonathan Epstein, M.D., associate professor of pathology and urology.
"We found that the best way to determine which men should undergo surgery is by using the results of a biopsy and a PSA density measurement," says Epstein, the senior author of a paper describing the guidelines, published in the February 2 issue of the Journal of the American Medical Association.
Because prostate cancer cannot always be identified through rectal examination during a physical in the doctor's office, physicians measure the blood levels of prostate specific antigen (PSA), a protein made by the prostate. However, results of PSA tests can be misleading, according to Patrick C. Walsh, M.D., director of the Brady Urological Institute at Hopkins and the paper's second author. Both normal and cancerous prostates make PSA.
Physicians use a special measurement of PSA called PSA density for determining whether a man has prostate cancer, PSA density is a number that represents the concentration of PSA divided by the size of the prostate. The result is a measure of PSA per gram of prostate tissue. The prostate size is measured by means of ultrasound.
"With the advent of PSA screening, there has been concern that many patients with small, incidental cancers would be diagnosed and subjected to treatment unnecessarily," Walsh says. "This is not the case in most patients. However, in this study we found that 16 percent of men fell into this category," Walsh says. "This small group of men who have very small cancers diagnosed through PSA screening might be followed through watchful waiting, rather than through treatment." Watchful waiting includes PSA tests every six months, and a biopsy once a year.
In the Hopkins study, the prostates of 157 men who underwent surgery for prostate cancer were analyzed to determine how often small, insignificant cancers occurred. The research compared these findings with the results of preoperative tests to determine how accurate the tests were in identifying men whose cancers were not large enough to have required surgery.
The guidelines require specific findings for both PSA tests, prostate size estimate by ultrasound, and cancer biopsies. The total PSA level in the blood must be less than 15 percent of the total weight of the prostate gland, which can be estimated by means of ultrasound.
In addition, no more than three biopsy samples can show evidence of cancer, and no single biopsy can be made up of more than 50 percent of cancer tissue.
"But a patient must have both good biopsy results and low PSA density for us to categorize him as not having significant prostate cancer," Epstein points out. "In the future, we will look at the rate of change in PSA in the blood over time. If this PSA level increases rapidly during watchful waiting, we will be more aggressive in treating the patient."
Another factor in the controversy over watchful waiting is the age of the man when he is diagnosed with cancer. Men in their late 70s or 80s usually die from causes other than their prostate cancer, Epstein points out. "However, men in their 50s and early 60s with prostate cancer are more likely to live long enough to die from that disease. So according to the guidelines, most of these men would be recommended for treatment."
"Men in their upper 60s who have insignificant prostate cancer are good candidates for watchful waiting," adds Walsh, the paper's second author.
Other authors of the paper include Mame Carmichael and Charles B. Brendler, M.D.