Tuesday, October 6, 2015

Should I get a PSA?

The decision to screen for prostate cancer seem so obvious.  For men, it is the most common cancer, and the second leading cause of cancer death.  For year, it was assumed that every man after the age of 50 would get a Prostate Specific Antigen blood test (aka PSA) every 1-2 years.  Ideally this would lead to a decrease in cancer deaths.  Unfortunately this has not turned out to be the case.

The US Preventive Services Task Force is a body that is funded by us (taxpayers) to look into health issues with objectivity (they're not physicians/drug companies who will profit off of treatment or even advocacy groups that are wired to make their issue the most important in public discourse or health insurance companies who are looking to save money).  You can see their most recent statement here.

In the past, if a man wanted to get screened, I would caution them that even if the PSA is normal (<4 abnormal="" and="" cancer="" could="" f="" get="" ignore="" nbsp="" not="" psa="" should="" still="" symptoms.="" the="" they="" were="">4), they should not panic because most of the time, a PSA>4 does not represent cancer anyway.  Great test right?  If they could live with the fuzziness of the PSA test, willing to not panic with every test >4 then maybe it would be useful for them.  If it was high (>4), I would recheck it in a matter of months.  If it were high again, I would refer for biopsy and then we could stop and make a decision about how aggressive to treat AFTER the biopsy.  I have a cousin (not a physician) who advocated on a blog post that patients should decide if they want to pursue screening and how aggressive to treat but physicians should not decide ahead of time paternalistically.  I agree with this on face value but when looking at the data, it becomes much messier.  

So looking at the data
For every

1000 men who under go screening for 10 years,
5 will die from prostate cancer if not screened
At most 1 will have their death prevented by being screened

Harms are significant
100-120 men will get biopsies (1 will get hospitalized from complications)
110 men will get a diagnosis of prostate cancer (and the accompanying worry)
29 will develop erectile dysfunction due to treatment
18 will become incontinent (lose control of bladder function)

So the ration is for every 1 person helped by screening
100-120 men get a procedure they don't need
110 will get a diagnosis and worry
29 will get ED, 18 will get incontinence.

The problem with this is that for the 110 men diagnosed with prostate cancer, it is very difficult to hit the brakes and not pursue further treatment.  In some ways, the guys who know they won't do anything about it should not get screened in the first place.

So this is the dilemma of prostate cancer screening-it is an emotional dilemma with physical outcomes.  Most men, clearly would be better off without being screened.