study of the week

Study of the Week- Screening for Ovarian Cancer

It’s very rare that a month goes by without someone bringing me a copy of this email.  It’s been circulating on the internet since 1998.  It is a true story, with some caveats, about a woman named Carolyn Benivegna who was diagnosed with ovarian cancer.  In the email, she implores women to DEMAND a CA-125 test on an annual basis and to “not take no for an answer.”  According to her email, if only this simple, accurate test was done, her diagnosis would have been made earlier, thereby improving her odds of survival.

So, what is a CA-125 test?  It is simple to do.  It’s just a blood test.  It measures CA-125, a protein that is found in higher concentration in tumor cells.  In general, it is higher in ovarian cancer cells than other cells. However, many conditions can cause a CA-125 to be elevated, including endometriosis and fibroids.  This means the test is very non-specific, meaning that there will be a lot of false positives (people have a high CA-125 but don’t actually have ovarian cancer).  Many people might read this and say, so what?  Who cares if there is a false positive?  I’d rather know if I have cancer, and I don’t care if it involves some extra testing!

So, here’s why that is not the right way to look at this.  This is a recent study published in JAMA.  It discusses some of the results of the PLCO Trial.  The PLCO trial is a 10 year study slated to be completed in 2015.  It evaluates screening methods for prostate, lung, colorectal and ovarian cancer.  The results of the ovarian cancer screening arm are very interesting.

The study looked at 78,216 women.  Half of them were randomized to receive ovarian cancer screening in the form of an annual CA-125 test and transvaginal ultrasound (to look at the ovaries).  The other half had “usual care,” basically meaning no screening.  Here are the results:
     212 women in the screening group were diagnosed with ovarian cancer; 118 of them died
     176 women in the usual care group were diagnosed with ovarian cancer; 100 of them died
     5838 women in total died of other causes
     There was NO decrease in mortality in the screening group
     3285 women had false positive screenings
     Of those, 1080 had unnecessary surgery, 32.9% of the had their ovaries out
     15% of those having unnecessary surgery had a major complication
     There was no “stage shift” in diagnosis, meaning that the screening group cancers were not discovered at an earlier stage than the usual care group.


So, here’s the take home message.  CA-125 and transvaginal ultrasound are not good screening tests for ovarian cancer for the average women.  Period.  Not only do they not detect cancer earlier, they lead to unnecessary and harmful surgeries.  Period.  The other take home message?  Women were 20 times more likely to die of something other than ovarian cancer.  I can’t stress this enough.  It’s easy to get scared about the possibility of cancer, especially one that there is no good screening test for.  However, ovarian cancer is rare.  Women are much more likely to die of heart disease and stroke than all other cancers combined.  So eat right, exercise, watch your cholesterol, and take your blood pressure medication!

     

3 thoughts on “Study of the Week- Screening for Ovarian Cancer”

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