Headlines
As reported by The Hartford Courant, September 7, 2005.
Study Reviews Prostate Screening
Brighter Statistics May Be An Illusion
By Garret Condon
Reports of improved success in treating prostate cancer may be largely the result of "grade inflation" in the classification of tumors, according to a study published today by researchers from the University of Connecticut Health Center, St. Francis Hospital and Medical Center, UCLA and McGill University in Montreal.
When decade-old biopsy samples were interpreted anew in the study, most were classified as being more dangerous than when they were originally classified. Assuming that the practice is widespread, it would mean that contemporary prostate cancer patients with a certain category of tumor appear to be doing better than patients diagnosed 10 or more years ago. In one analysis in the study, the death rate appeared to drop 28 percent in a decade. But most of this could be due to the "upcoding" of the cancers.
"You get the impression that your treatments are making a difference," said Dr. Peter Albertsen, professor and chief of urology at UConn Health Center and lead author of the study, published in the Journal of the National Cancer Institute.
The study adds weight to the argument that, since 1985, when the prostate-specific antigen test began to be used as a prostate-cancer screening test, many men with benign tumors have been treated unnecessarily or too aggressively. Some researchers have argued that the PSA test is increasingly finding more serious tumors, but today's study suggests that while the tumor scores may be going up, the scores don't always reflect an actual increase in the seriousness of a tumor.
Researchers assembled records from 1,858 men who underwent biopsy for prostate cancer in Connecticut and in nearby Westerly, R.I., from 1990 to 1992. For each case, the original biopsy slides, showing prostate tissue, were made available, as well as the original Gleason score - a scale of between 2 and 10 used by pathologists to estimate the likelihood a cancer will spread.
Pathologists - who did not know the original Gleason scores - recently were asked to rescore the old slides.
The result showed prostate cancer grade inflation. The study found that 55 percent of the specimens received higher Gleason scores than they had originally received. Where the average score of the specimens had been 5.95 originally, the new scoring brought the average to 6.8.
Pathologists arrive at a Gleason score by looking for five increasingly aggressive patterns (scored 1 to 5) in biopsy tissue. They first assign a 1-to-5 score for what they see in the majority of the tissue. This is added to a second 1-to-5 score for what is seen in the remainder of tissue. Thus a 2 is the lowest combined score and a 10 the highest. Albertsen said that a pattern score of 1 is almost never used these days and pattern 2 is rare.
Today's biopsies often are done using a biopsy gun, which samples a much smaller piece of tissue than traditional biopsies, Albertsen said. Pathologists, therefore, are making the call on much smaller chunks of tissue. Also, pathologists have little incentive to low-ball the scores, said Albertsen, because scores are frequently revised upward after men undergo prostate removal and the entire gland is examined.
Albertsen said that the findings could mean that when patients have scores in the 6 range, doctors should consider "watchful waiting" for some of them, but not all. He acknowledged that conservative management of cancer is often the last thing patients want to hear after they've heard the word "cancer," and that the threat of lawsuits often pushes physicians to treat a patient's tumor even when it might make sense to hold off.
In an accompanying editorial in the same issue of the journal, Dr. Ian M. Thompson and two colleagues from the University of Texas Health Science Center at San Antonio wrote they are concerned that the "grade inflation" described by Albertsen's study is part of the "phenomenon of over detection and over treatment of prostate cancer" triggered by the widespread use of the PSA test.