Last week the US. Preventative Task Force recommended against the routine use of PSA tests to look for prostate cancer in otherwise healthy men with no symptoms. Patient advocacy groups are organizing to fight the latest task force recommendation by showcasing men who were supposedly saved by this test (by having their prostate cancer diagnosed early and treated). Undoubtedly, there were some that were. The problem is, we don’t know exactly who.
There are 3 important and relatively new concepts to understand about cancer I feel everyone should understand before going to their doctor for screening:
1. Each type of cancer (prostate, breast, lung, lymph etc.) is a Baskin-Robbins disease: that is to say they come in about 31 different flavors. Slow-growing, fast growing, likely to spread, unlikely to spread, primitive cell type, specific cell type, possessed of treatable gene mutations, not in possession of treatable gene mutations…and on and on and on. For example, while Rocky Road may be a killer, Strawberry is likely to stay with you until the day you die. Yet, both are just called “ice cream” by us today. Take away: NOT ALL PROSTATE CANCERS ARE THE SAME THING AT ALL!
2. Every adult has a cancer growing in them somewhere. Did you know that studies have shown that cancer was found in over 40% of males (who died in accidents) between the ages of 40 and 49? That’s almost half of men in that age range! The percentage increases to almost 70% in the 60-69 age group. SO, it appears that prostate cancer is almost a normal condition in most adult males. The lifetime chance of being diagnosed with prostate cancer is 16% but the lifetime risk of dying from prostate cancer is 3%. Important to know that most men who die of prostate cancer are elderly: the median age of a guy who dies from prostate cancer is 80. SO CLEARLY, MANY OF THE CANCERS GROWING IN MEN’S PROSTATES are either: slow-growing, only there for a while, or very non-aggressive and unlikely to spread. And yet….
3. there are some cancers that are fast growing, aggressive and strike in the prime of life….however, we’re still not sure that catching them early makes any difference! That is the concept that is the hardest to grasp by doctors and patients alike. Still, most doctors are confident that there are some flavors of cancer, say mint chip, who are aggressive and likely to cause a premature death in their hosts AND who respond to available treatments (surgery, radiation, chemotherapy and/or hormone therapy) For this group, PSA screening makes all the difference. Unfortunately, since the death rate from prostate cancer has not changed much since PSA tests became common, the mint-chips are pretty rare.
What to do? Cancer screening is one of the hardest things doctors have to explain to their patients. Even worse, with prostate cancer, the treatment may very well be worse than the disease (impotence, fatigue, incontinence). Knowing if a patient falls into a high risk group for prostate cancer: black men and those with a first degree relative who died of prostate cancer can help patients and physicians decide how aggressive to be about an abnormal PSA test. It all comes down to weighing risks and benefits and understanding trade-offs. Not an easy equation.
The long and the short of cancer screening is: we’re not just looking for ice cream, we’re looking for mint-chip, and we don’t have the best screening tools to find it yet.
-Jennifer Brokaw, MD
US Preventative Task Force PSA Screening Recommendations: Oct 2011.
Overdiagnosed: Making People Sick in the Pursuit of Health by Welch, Schwartz and Woloshin. 2011