Nov. 22, 2010 -- One of the first things that a man wants to know after he has been diagnosed with prostate cancer is the cancer’s stage, which is supposed to indicate the extent of the disease and help predict the likelihood of recurrence after treatment.
The findings are published online in the journal Cancer.
More than 186,000 American men are diagnosed with prostate cancer each year, according to the National Cancer Institute.
Localized prostate cancer is staged as T1-T2, but there are several problems with the system. The stage is based on your doctor's estimate of the extent of the prostate cancer. This assessment is based on the results of a physical exam, lab tests, biopsy, and imaging tests.
In the new study, researchers analyzed data on 3,875 men who were diagnosed with localized prostate cancer at 40 urology practices between 1995 and 2008. They found that doctors improperly staged the cancer 35.4% of the time.
Even after researchers corrected for these inaccuracies, the stage still did not correlate with risk of recurrence after removal of the gland, a procedure called radical prostatectomy.
Predicting Prostate Cancer Recurrence
“There appear to be several problems with our current clinical staging criteria for prostate cancer,” explains study researcher Adam Reese, MD, chief urology resident at the University of California, San Francisco.
But “there are several other variables available to the practitioner at the time of diagnosis which are strongly associated with prostate cancer recurrence after radical prostatectomy,” he says.
Other important variables include the tumor’s Gleason score or grade and the percent of positive biopsy cores or the number of cancerous cells taken during the prostate biopsy.
“These variables seem to be more powerful predictors of recurrence than clinical stage,” Reese says. “These data should be emphasized in preoperative counseling and less weight should be placed on clinical stage data,” he says.
“We don’t have a good way of staging localized prostate cancer,” says Reza Ghavamian, MD, director of the prostate cancer program at the Montefiore-Einstein Center for Cancer Care and director of urologic oncology and robotic urology at Montefiore Medical Center in New York.
“There are more important predictors of prostate cancer outcome including PSA level, Gleason score, and positive biopsy samples,” he says.
Clinical stage is still important for prostate cancers that have spread outside of the prostate gland, he tells WebMD.
“Some patients say, ‘What stage am I?’ and we usually tell them that they have local disease or that their chances of a spreading cancer are such and such,” he says.
Imaging of Prostate
One of the issues with staging is the lack of a good way to capture images of the prostate, he says.
“Ultrasounds are not a very accurate way of visualizing the prostate,” he says. “You can’t do an ultrasound and say ‘you have prostate cancer,’” he says. Most urologists use transrectal ultrasound to direct the needle during biopsy, he says.
Digital rectal exams (DRE) are also very subjective, he says. During a DRE, your doctor uses a finger to feel for lumps or enlarged areas that could suggest prostate cancer. “Some doctors may feel something subtle and some may not,” he says. “These tests are subject to tremendous intraobserver variability and the assignment of clinical stage is fraught with difficulty.”
American Cancer Society Chief Medical Officer Otis W. Brawley, MD, says it can be hard to determine which localized prostate cancers will recur. “There are some small localized prostate cancers where some of the disease has already broken off and moved outside the body to the bones, and there are some large localized prostate cancers where some of the disease has not moved off to bone and will never move off to bone and cause harm,” he says.
The issue is that doctors don’t know how to predict which way the tumors will go, he says.
What is really needed is a genetic screening test that can tell whether or not this tumor is likely to spread or stay put, he says.