Standard Biopsies Miss 1 Out Of 7 Prostate Cancers, Ohio Team Says
COLUMBUS, Ohio /PSA Rising/ July 6 2001- Traditional biopsy methods for prostate cancer are likely to overlook the disease in one out of seven cases, according to a new study done at Ohio State University.
Other studies in the Germany and Italy have found up to thirty percent of prostate cancer tumors are missed by the traditional method.
In a standard ultrasound-guided needle biopsy, called a sextant biopsy, the urologist takes six tissues samples from the prostate. Taking extra samples from the transition zone of the prostate is known to increase detection rates of the cancer of the prostate, especially in patients with negative digital rectal examination. Some urologists already take eight or ten samples in all, and others recommend more.
To see how effective a larger number of samples might be and how much extra discomfort it is likely to cause the patient, Dr. Robert Bahnson and colleagues in Ohio State's Division of Urology increased the number of tissue snips to twelve.
The result was, 10 men out of a total of 74 in the study group were diagnosed with prostate cancer which would not have been found using the traditional six-sample method. Another thirty men out of the 74 were diagnosed on the basis of the older method.
The men ranged in age from 46-98 years (median age of 62.3 years). They underwent biopsies because preliminary tests showed either an elevated level of prostate specific antigen (PSA) and/or a digital rectal exam found a possible abnormality. This year alone, physicians expect to detect an estimated 198,000 new cases of prostate cancer.
"Somewhere between 10 and 20 percent of the cancers in these men," Bahnson said, "might otherwise be missed by using the traditional biopsy approach." The technique Bahnson used is called the extended sector biopsy. Ordinarily, a physician takes six tissue samples from the outer rim of the prostate. Bahnson took an additional six tissue samples from inside the gland - two samples in
each peripheral zone and two in the transition zone.
"The prostate is like a sphere," Bahnson said. "The area where cancer is most often found is kind of like a horseshoe around the outside." The six additional areas are just inside this horseshoe area.
Forty subjects in the study tested positive for adenocarcinoma - cancer of the lining or inner surface of an organ. In 10 of these men (13.5 percent of the study group), cancer was found only in one or more of the six additional areas. In 8 of
the 10 patients with "sector only" cancer, tumor was detected in the peripheral zone;
in 1 in the transition zone and in 1 in both zones.
All 10 patients had a Gleason pattern score
3+3=6 or 4+3=7. There were no atypical or PIN cores found in the sector zones only.
PSA ranged from 1.2-142 (median 6.0 ng/ml). The median PSA was 6.2 ng/ml in all
patients found to have cancer, and 6.0 ng/ml in the cancers detected only in the
additional zones. There was 1 (1.4%) complication of urinary retention and fever.
Bahnson and his colleagues now use the extended sector biopsy test as a matter of routine, and have reduced the biopsy number to 10 tissue samples. "Cancer is rarely detected in the inner portion of the prostate," he said.
Detecting prostate cancer in its early stages has gotten easier for doctors and patients alike. The advent of the PSA measurement has led to a "tremendous increase in the number of routine biopsies performed each year," Bahnson said.
As a result, the age at which cancer is diagnosed has fallen from a median of 71 years in the pre-PSA era to a median of 67 years after the development of the PSA test. This median age at detection must not be confused with possible age at which the disease develops. Some men develop significant or aggressive prostate cancer by the start of their forties. African American men and men with a family history of the disease are especially recommended to take the PSA test by age 40.
Prostate cancer that has spread outside the gland is not, at present, curable. It is crucial to detect the disease while it is still organ-confined. The number of prostate cancer found at this organ-confined stage has risen from 13 to 30 percent since the introduction of the PSA test in the late 1980s, Bahnson said. Although this more extensive biopsy technique won't result in the same kind of jump in early detection rates, he says the extended sector biopsy is expected to reduce the time it takes to detect prostate cancer and reduce cost of treatment.
"One of the reasons for doing a more extensive biopsy is that there is a certain percentage of patients who we bring back for a second biopsy and do find cancer," Bahnson said. "If we can eliminate the need for a second biopsy, all the better for the patient."
The study, Extended sector biopsy for detection of carcinoma of the
prostate, appeared in a recent issue of the journal Urologic Oncology. Co- authors Robert Bahnson, Paul Arnold and Theodore Niemann all belong to the Division of Urology at Ohio State University, Columbus, OH. Support for their research came from The Charles S. & Mary Coen Family Foundation.
Links to Related Material
Urol Int 2001;66(4):197-200
Morbidity and discomfort of ten-core biopsy of the prostate
evaluated by questionnaire.
Manseck A, et al.
Department of Urology, Technical University of Dresden, Germany.
Arch Ital Urol Androl 2000 Dec;72(4):258-63
[Ultrasound-guided biopsy: screening of prostate cancer with
a single set of 14 systematic biopsies].
[Article in Italian, anstract in English]
Perdona S, et al. Dipartimento di Urologia e Nefrologia, Azienda Universitaria Policlinico, Universita
degli Studi Federico II, Napoli. "This strategy enhance prostate cancer
detection [by] 30% compared to conventional sextant biopsies alone. In conclusion,
the 6 systematic biopsy of the peripheral zone [is] inadequate and a minimum of 12
with extensive core in peripheral and transitional zone should routinely be
performed to detect a more significant number of men with prostate cancer at
stage T1c."
