Scanning electron micrograph of prostate cancer cells. Image courtesy of Anne Weston, Wellcome Images.
It’s Prostate Cancer Awareness Month: A Q&A with Drs. Kane and Parsons
After skin cancer, prostate cancer is the second most common cancer among males. More than 217,000 new cases are diagnosed annually. One in six American men will be told they have the disease at some point in their lives. By age 85, it is estimated three-quarters of all men have prostate cancer.
Yet prostate cancer remains an especially confounding disease. It grows so slowly that symptoms may not appear until late in life, if ever. Yet it’s also indisputably deadly. At least 32,000 American men die from it each year.
We asked two leading physician-scientists to talk about the study and treatment of prostate cancer: Christopher Kane, MD, chair of the Department of Urology and professor of surgery at the UC San Diego School of Medicine and J. Kellogg Parsons, MD, MHS, associate professor of surgery at UC San Diego Moores Cancer Center and vice chair of the National Comprehensive Cancer Network Expert Panel on Clinical Guidelines for the Early Detection of Prostate Cancer.
Question: The risk of prostate cancer increases with age. Most doctors recommend healthy men over the age of 50 be screened for the disease annually. The American Urological Association suggests starting at age 40.
Kane: The best argument in favor of screening is that more than 30,000 men die from prostate cancer each year in the United States. If you get screened, you can get treatment, if needed. Screening is gaining information about whether or not a person has prostate cancer and, if they do, the stage, grade and severity of the disease. Fortunately, most men who are diagnosed young are diagnosed at a stage where they can be cured, experience fewer side effects, and are more likely to benefit from treatment.
Parsons: Most urologists agree that beginning at age 45 to 55 years, men should get a PSA blood test and prostate exam every 1 to 2 years. Regular screening is particularly important for men who either have a family history of prostate cancer (even just one first-degree relative) or men who come from an African-American family. In African-American men, prostate cancer tends to be more aggressive at a younger age.
Q: What is the PSA test?
Kane: PSA stands for prostate specific antigen — a fluid which is normally present in semen. Elevated levels of PSA in blood serum are associated with benign prostatic hyperplasia (prostate enlargement) and prostate cancer. A test for PSA may be used to screen for prostate cancer and to monitor treatment of the disease.
Q: Last year, the United States Preventive Services Task Force said healthy men should no longer receive the PSA blood test for prostate cancer because the screening does not save lives overall and often leads to unnecessary, debilitating tests and treatments. What’s your opinion of the panel’s reasoning and decision?
Kane: I disagree with the task force’s conclusion, as do major health organizations. It’s true that PSA is an imperfect test. Although it is sensitive, meaning that most men with prostate cancer do have an elevated PSA, it is not specific for prostate cancer, meaning many men with an elevated PSA don’t have cancer. So the concern of the task force is that men with elevated PSAs go through additional diagnostic tests that can be uncomfortable and often don’t show cancer.
The other concern is that many men with slow-growing prostate cancer don’t necessarily need to be treated and “overtreatment” can lead to adverse sexual and urinary side effects. What the task force seems to minimize is that prostate cancer is the second leading cause of death in American men and many men with prostate cancer detected by PSA do have life threatening cancers and can be cured with current treatments.
Q: The lower the PSA test score, the better. What is a worrisome PSA number?
Kane: One of the popular misconceptions is that a normal PSA is anything under four. This is not true for everyone. PSA must be used in the context of age and ethnicity. An average PSA for a man in his 40s is about 0.8 nanograms per milliliter. An average PSA for a man in his 50s is about 0.9-1.0 ng/ml and really should be under 2.5. PSA velocity – the rate of change of PSA – is a very strong predictor of prostate cancer. PSA velocity is also correlated with grade and severity of cancer. A PSA history that suddenly changes is a more valuable indicator of disease than a single elevated PSA.
Q: For healthy men over age 50, is there a viable alternative to a PSA screening?
Kane: No, for prostate cancer screening, both a PSA and a digital rectal examination are the best tests for men to catch prostate cancer in its most treatable stage. I continue to recommend screening and risk stratification of whether a man has aggressive or more slow-growing prostate cancer. We should then institute safe, effective, curative therapy, usually with surgery or radiation therapy for men with aggressive prostate cancers, and carefully follow, without treatment, men with more indolent, non-aggressive cancers.
Q: What about prevention? Does diet play a role?
Parsons: We have followed large groups of patients in epidemiological studies, and, over time, based on what they tell us they eat, we have been able to make conclusions about what would be some of the most advantageous dietary changes.