The pros and cons of the PSA test for prostate cancer.
Should you or someone you care about have a PSA screening test? The U.S. Preventive Services Task Force recently issued a draft recommendation against routine screening for men who have no symptoms of prostate cancer, regardless of age, race, or family history.
The draft recommendation was based on a review of five screening trials, where the two largest studies reported conflicting results. The U.S. study found that the death rate from prostate cancer was very low overall and did not differ significantly between the annual screening group and the usual care group, who sometimes received screening. The European study, found a 20% reduced risk of death for the group that received screening, compared to the group that did not, but also found a high risk of overdiagnosis. Those researchers calculated that 1,410 men would need to be screened and 48 additional cases of prostate cancer would need to be treated to prevent one death.
“I think the Task Force made a huge inference about all the steps that occur from PSA screening to subsequent diagnosis, to choosing to get treated, to actually receiving treatment,” says Dr. Andrew K. Lee, M.D., M.P.H., a radiation oncologist at the University of Texas MD Anderson Cancer Center and Director for MD Anderson’s Proton Therapy Center.** He says, “When you examine the literature, keep in mind that they were tracking treatments and outcomes from twenty years ago and trying to apply that to modern therapy. Treatments have changed and so has our understanding of who is at risk.”
The American Urological Association (AUA) and the American Cancer Society both disagree with abandoning PSA testing altogether. The AUA recommends a baseline reading among men who wish to be screened at age 40, depending on personal risk factors such as ethnicity and a family history of prostate cancer. The American Cancer Society recommends that men who are at average risk should begin to discuss the benefits and risks of PSA screening with their doctor at age 50, or at age 45 if they are in higher risk categories which include African-American men or those with a family history of early prostate cancer.
So, should men have a PSA screening test or not?
The pros of PSA testing:
* A PSA score is obtained from a simple blood test, which detects the level of prostate-specific antigen, a protein that can be elevated in the presence of prostate disorders.
* Early detection of prostate cancer can save lives. About 240,890 new cases will be diagnosed in the U.S. in 2011, and about 33,720 men will die of prostate cancer, but more than 2 million U.S. men who have been diagnosed at some point are still alive today. Dr. Lee says, “If patients are not diagnosed until later, it may be too late for more minimally invasive treatment procedures that have fewer side effects than later stage therapies.”
* A change in a PSA score over time can indicate a need for further investigation, or can detect recurrence in those who have already received cancer treatment.
The cons of PSA testing:
* A PSA test cannot determine if a cancer is fast or slow growing. The majority of prostate cancer is thought to be slow growing, but Dr. Lee advises, “there are a lot of tumors that fall in between fast and slow, and a slow-growing cancer can change and start to grow at a faster rate.”
* Other factors can cause elevated PSA levels, such as a urinary tract infection, ejaculation within the last 2 days, inflammation from riding a bicycle, or an enlargement of the prostate that is common as men age. False positive readings can lead to unneeded biopsies and treatments like surgery and radiation therapies that carry increased risks of incontinence and impotence.
* Certain medicines used to treat urinary symptoms, herbal mixtures, steroids or aspirin may lower the PSA level, even when cancer is present. Obese men also tend to have lower PSA levels.
Ultimately, each man should make a personal decision and discuss their screening and treatment alternatives with their doctor, based on personal risk factors such as age, ethnicity and family history of cancer.
Breakthrough new detection methods are on the horizon. For example, investigators at the University of Michigan have developed a two-gene DNA urine test that can detect two biomarkers that are found in 95% of prostate cancers.
Dr. Lee points out that treatment therapies have advanced a long way in the last 10-20 years. Today, doctors may be able to perform nerve-sparing surgery, which spares one or both nerve bundles next to the prostate gland that are responsible for erections. Advances in radiation therapy options now include refined brachytherapy techniques (placing a small radioactive pellet or seed near the cancerous tumor), more effective radiation doses, and image-guided therapy. MD Anderson’s Proton Therapy Center is one of a few facilities in the world to offer pencil-beam scanning, which can precisely target a tumor and deliver a higher dose of radiation, while avoiding healthy tissue.
CONNECT THE DOTS
Is My Cancer Different? is a key question a newly diagnosed patient can ask their doctor. Clarient, a GE Healthcare company now offers clinicians molecular testing for a variety of cancers, including prostate cancer, that analyzes a tumor at the genetic level and can help oncologists identify targeted therapies and individual treatment plans. Know Your Stats About Prostate Cancer offers information about risk factors, the benefits of baseline screening, and questions to ask your doctor. Check out Movember, the global fundraising event in November to raise funds to support research for prostate cancer and other cancers that affect men.
Originally published on GE Healthy Outlook, December 21, 2011.
** February 9, 2015 update: “Dr. Andrew K. Lee, a renowned leader in oncology and innovator in proton beam therapy cancer treatment, has been named medical director of the Texas Center for Proton Therapy following a global search. Dr. Lee launched proton therapy treatment at The University of Texas MD Anderson Cancer Center almost nine years ago, treating the facility’s first proton therapy patient in 2006. In his new role, Dr. Lee will lead North Texas’ first facility offering the most innovative, next-generation proton therapy treatment technology.” PR Newswire