Tuesday, August 26, 20083
Screening for ovarian cancer
A fairly good article in the NY Times talking about a new blood test screening for ovarian cancer.
Ovarian cancer is normally not detected until the late stage of the disease, so patients have been eager to find an early screening test.
The downside is the unacceptable "false positive" rate (0.6 percent in this case), where the test is positive in the absence of disease. This often leads to removing the ovaries unnecessarily.
At $240 per test, companies profit from the public's fear of cancer and capitalize on the myth that "more testing must equal better medicine."
However, they leave out the thousands of unnecessary surgeries and procedures that arise from false positive readings. Equal weight to this complication should be included in their advertisements.
Ovarian cancer is normally not detected until the late stage of the disease, so patients have been eager to find an early screening test.
The downside is the unacceptable "false positive" rate (0.6 percent in this case), where the test is positive in the absence of disease. This often leads to removing the ovaries unnecessarily.
At $240 per test, companies profit from the public's fear of cancer and capitalize on the myth that "more testing must equal better medicine."
However, they leave out the thousands of unnecessary surgeries and procedures that arise from false positive readings. Equal weight to this complication should be included in their advertisements.
Comments
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PharmacistMike
It would be wonderful to see a screening test for ovarian cancer but this is starting to smell like the female version of the PSA test. With no real ability for biopsies there may be a lot of ovaries removed unnecessarily.
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Jon Lepley, D.O.
This summarizes preliminary results from the ovarian cancer screening arm of the PLCO trial:
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MuchaDO
The article states that 1 in 3000 women will have ovarian cancer in their lifetimes. With a false positive rate of ~ 1%, 30 of 3000 women will be shown to be "positive" for a higher risk of malignant cancer.
Post a Comment12:40 PM
http://www.nih.gov/news/pr/nov2005/nci-07a.htm
In this study of 28,816 women screened with a CA-125 and transvaginal US, 29 tumors were detected out of 570 women who ultimately ended up having a surgical procedure. 541 women underwent surgery who didn't have cancer. If my math is correct, a woman was almost 20X more likely to have unnecessary surgery than have cancer detected as a result of screening, and it's not known if these 29 women increased their life expectancy with earlier detection.
In short, i would be extremely skeptical of any screening test for ovarian cancer without randomized controlled trials.
6:15 PM
At 95% sensitivity, the one woman in 3000 will be found, but so will thirty others. What are the odds that YOU are that one? About 1/31 or 3 percent.
I wouldn't be particularly anxious to have my ovaries removed if my risk was only increased by 3 %. Would you?
10:46 PM