(RxWiki News) Men have gotten a lot of conflicting information relating to prostate cancer screening over the past few years. How often to get screened and when to treat a prostate tumor has been extensively debated. New research may clear up some of the confusion.
Most prostate cancers, according to a recent study, apparently don’t get more aggressive over time.
What this means is that if a man is diagnosed with an early tumor, taking a wait and watch approach may be safe because the cancer is not likely to become more deadly over time.
"Discuss prostate cancer screening with your doctor."
Kathryn Penney, ScD, an instructor in medicine at the Harvard Medical School and associate epidemiologist at the Channing Division of Network Medicine at Brigham and Women's Hospital in Boston, Massachusetts, directed this study.
She and colleagues looked at historical data regarding the stage (extent and spread of the disease) of prostate cancers diagnosed before and during the time that PSA (prostate-specific antigen) testing was widely used.
These researchers examined data from 420 participants in the Physician’s Health Study and 787 men recruited for the ongoing Health Professionals Follow-up Study. All of the men had been diagnosed with prostate cancer between 1982 and 2004.
Both studies used mailed surveys to assess and track lifestyle and medical history.
The researchers learned that PSA screening increased from 42 percent in 1994, when the test was first approved by the US Food and Drug Administration (FDA) as a diagnostic aid for prostate cancer, to 81 percent in 2000.
The proportion of men diagnosed with advanced cancers fell by more than six-fold during 1982-2004, that included the years prior to widespread use of PSA testing and the years during which the screening was widely used.
They found that the number of late-stage (advanced cancers that have spread) decreased from 19.9 percent in the 1982-1993 period to 3 percent in the 2000-2004 period.
However, the aggressiveness of the cancers as reflected by Gleason scores did not change markedly. High Gleason scores (more aggressive cancer) represented 25.3 percent of prostate cancers diagnosed between 1982 and 1993 and 17.6 percent of cancers detected in the 2000-2004 period.
After analyzing the reason for the drop in high Gleason grade cancers, the researchers discovered that the decrease didn’t occur because screening prevented the cancer from progressing to more aggressive disease.
Instead, the investigators learned, there was an increase in the diagnosis of low-grade disease that would not have been found without PSA screening.
“If Gleason grade progresses as stage does, one would expect a similar reduction in high-grade tumors,” the authors wrote.
“Although we cannot rule out the possibility that Gleason grade progresses within an individual, we conclude that it is not a major feature of prostate cancer,” the authors concluded.
Common treatment for any stage of prostate cancer includes the removal of the prostate, radiation and/or chemotherapy. The side effects of this treatment include sexual problems and difficulty controlling the urinary and bowel functions.
As a result of these findings, Dr. Penney said in a prepared statement, "Men with low-grade disease at diagnosis should seriously consider talking with their doctors about active surveillance."
Active surveillance includes regular testing and biopsies as needed to monitor the disease over time.
This study was published in the August issue of Cancer Research, a journal of the American Association for Cancer Research.
This work was supported by the Dana-Farber/Harvard Cancer Center Prostate SPORE and the National Cancer Institute. No potential conflicts of interest were reported.