Men who show no suspicious signs of prostate cancer on rectal examinations
and who also have a prostate specific antigen (PSA) level below 2.0 apparently
could safely wait two years before their next PSA test, according to an
article in a recent cancer theme issue of The Journal of the American
Medical Association (JAMA).
H. Ballentine Carter, MD, from The Johns Hopkins University School of
Medicine, Baltimore, and colleagues examined PSA measurements of 312 men
who took part in the Baltimore Longitudinal Study of Aging. Forty of those
men eventually developed prostate cancer; the other 272 men did not have
prostate cancer. Frozen sera from the men enrolled in the study were measured
at two- and four-year intervals.
The researchers compared these measurements with case studies of 389
men who were treated surgically for non-palpable prostate cancer.
In an interview, Dr. Carter said: "We were able to establish, number
one, what is the appropriate PSA level that would increase the detection
of both curable and significant cancers-and the answer to that part of
the study was a PSA between 4.0 and 5.0.
"It turned out that prostate cancers detected at PSA levels less
than 4.0 are almost always curable cancers-but over half of them are cancers
that are so small that treatment may not be necessary." The alternative,
he says, is "watchful waiting or expectant management."
Dr. Carter says when the pre-treatment PSA level was greater than 5.0,
the vast majority of tumors were significant (87%)-and 30% of them were
no longer curable.
"Large Health Care Cost Savings"
Dr. Carter says the study also found that when PSA levels are less than
2.0-"rarely will the PSA level exceed 4.0 or 5.0" after two years.
In other words, a two-year testing interval is apparently sufficient to
safely detect curable prostate cancer in men whose PSA levels measure less
Since 70% of a screened population of men aged 50 to 70 have PSA levels
below 2.0, Dr. Carter and his colleagues write: "Elimination of annual
PSA testing for these men would result in large health care cost savings."
Dr. Carter emphasizes that any recommendation for PSA testing every
other year would apply only to men with PSA levels under 2.0 and no suspicion
of prostate cancer found on rectal examinations. For men whose PSA levels
are above 2.0, "it would appear that yearly testing is probably necessary."