Sunday, October 9, 2011

PSA: To Screen or Not to Screen

There has been much confusion/concern/media attention since the recent announcement (see the NY Times article US Panel Says No to Prostate Screening for Healthy Men) that PSA tesing was no longer recommended by the US Preventative Services Task Force. (Here's the full version of their draft recommendation.) There are many responses out there (Tara Parker Pope's Answering Questions about the PSA test is a good one), but I believe there is still more to say on the issue.

Before answering the question regarding whether we should follow the USPSTF's new recommendation, please consider...

1. The USPSTF is the same group that says
-Women shouldn't get mammograms before 50
- Recommends against teaching self-breast examination
-States that screening for testicular cancer is harmful
-Only recommends screening for diabetes in patients with high blood pressure
-Recommends against screening for depression for most primary care doctors

(I am not stating that I necessarily disagree with these recommendations.  However, it is important to understand where USPSTF is coming from when considering their PSA recommendation). 

2. Prostate cancer is still a leading cancer killer for men in the US. 
From NY Times:

One in six men in the United States will eventually be found to have prostate cancer, making it the second most common form of cancer in men after skin cancer. An estimated 32,050 men died of prostate cancer last year and 217,730 men received the diagnosis. 

The new recommendations come from findings of two large studies.  One in the US that showed no benefit in saving lives, and one in Europe that showed only some benefit.  The US study have some major limitations, including that many of the men in the placebo/no-screening group actually got screened, so I will focus on the European study.

The European Randomized Study of Screening for Prostate Cancer looked at close to 200,000 men between 50-74 for about 9 years. Not surprisingly they found almost double the rate of prostate cancer in the screened group compared to the non-screened group (8.2% vs. 4.8%).  More importantly, they reduced the rate of death by about 20%. Unfortunately, most of the men treated for prostate cancer did not benefit.  They found that for every 1410 screened, there were 48 additional cases of prostate cancer found, that if treated would only prevent one death from prostate cancer. In other words, if you are treated for prostate cancer, there's only about 1/50 chance it will save your life. Now, if the treatment were without side effects, then besides costs, there would be no reason not to screen.  (My friend Dr. Stewart Segal in his post PSA Confusion suggests covert rationing is one motivation behind the USPSTF's recommendation).  The problem is that there are side effects with treatment, and not inconsequential ones. There is about a 20-30% chance of impotence, incontinence or both. 

However, there seems to be two things not discussed in any of the reports:
1. Though the writers of the guideline seem to give value/risk of the harms of treatment, they do not address the potential benefits of the piece of mind from a negative screen.  In the European study, over 90% of men had a negative screening over the course of almost a decade.  In other words, the vast majority of men screened had the piece of mind knowing that probably didn't have to worry about prostate cancer. (There is also additional evidence that men 65 and older with a very low PSA  will likely never get prostate cancer, and screening should be stopped). 
2. Just because you are diagnosed with prostate cancer, doesn't mean you need to treat it.  Given the complications as a result of prostate cancer treatment, and the fact that prostate cancer tends to progress slowly, especially after the first year, watchful waiting is a reasonable approach. If in fact, if the cancer remains stable, treatment can be deferred potentially indefinitely.  However, without the diagnosis, watchful waiting can not occur. 

Bottom Line:  There is no right answer for everyone.  Patients, in consultation with their doctor, need to make a decision that's right for them.  If you are a healthy person, with no cancer risks, worry about side effects and complications of medical treatment,  and realize that there's a 98% chance that screening for prostate cancer will not save your life, you should not get a PSA test or prostate exam.  However, if you are someone that is very fearful of cancer, would have substantial piece of mind if you were one of the 90% of men that tested negative, and if you did get diagnosed with prostate cancer are willing risk treatment knowing there is only a 1/50 chance it will save your life, but about a 20-30% chance you will get side effects from treatment, then you should get tested. 

No comments: