Some experts and the FDA say that a test that finds ovarian cancer early is "premature and it has not been proved to work."
Here's the problem: some experts and the Food and Drug Administration (FDA) say that a test that finds ovarian cancer early is "premature and it has not been proved to work." With the possibility of a high false positive rate, they say "it might do more harm than good, leading women to unnecessary surgeries."
A test called OvaSure has been marketed since late June, 2008 by LabCorp. They tout it can find ovarian cancer at its earliest stages, that is, when the cancer is still confined to the ovaries. According to the American Cancer Society, more than 90% of women will live at least five years if the cancer is detected and managed at that point, but to date, only about 20% of cases are detected that early. Moreover, when it is detected in its later stages and it has spread, only about 30% of patients then will survive five years.
"In a study published in the journal, Clinical Cancer Research in February, the test correctly classified 221 of 224 blood samples taken from women with ovarian cancer or from controls. It identified 95 percent of the cancers, and its false positive rate -- detecting a cancer that was not there -- was 0.6 percent." However, there were "very few blood samples from women with early stages of the most deadly type of ovarian cancer."
Dr. Berchuck of Duke said only 1 of 3,000 women has ovarian cancer. So even if a screening test had a 1 percent rate of false positives, it would mean that 30 out of 3,000 women tested might be subject to unnecessary surgery for every one real case of cancer.
Dr. Gil Mor, the lead developer of the test at Yale, said the use of OvaSure might reduce ovarian surgeries, not increase them. That is because women with BRCA mutations often have their ovaries removed to prevent cancer. A negative result on the OvaSure test might allow such women to put off the surgery.
Whereas mammograms and P.S.A. (prostate) testing were fairly unreliable, they can lead to a needle biopsy. In the case of ovarian cancer, because a needle Bx is more difficult, unless imaging is telling, an oophorectomy is more likely.
Pollack A. "Cancer Test for Women Raises Hope, and Concern." NY Times Published: August 25, 2008
Below, some reader responses:
On Tue, Aug 26, 2008 at 5:14 PM, Fredrick H (MD [oncology], PhD, JD wrote:
Since the test may have a few percent of false-positives, the nay-sayers bleat about the "danger" of unnecessary surgery. The current 5Y survival rate for women diagnosed with ovarian cancer is about 45%. Cases diagnosed early have a 5YS of about 90%. This test is alleged to have specificity of over 90%, so there should be fewer than 10% of women who get "unnecessary surgery," especially if use of the test is limited to high-risk women. (The only people who hate "unnecessary surgery" are those who have to pay.) But the death rate from an exploratory laparotomy is nil, compared with the over 50% death rate from late diagnosed ovarian CA. Just WHAT are these guys thinking, in trying to suppress the use of this test? Whose interests are they serving?
From: Mench M
To: MDNG (Dr. Kaplan)
Subject: Re: [Dialog] Ovarian Cancer Test pooh-poohed by FDA and surgeons
What percentage of false-positives would make it not worth doing the surgery? Is the death rate of this surgery and anesthesia really nil with no one or almost no one dying?
Sent: Aug 26, 2008 8:14 PM
If the gynecologist does a diagnostic laparoscopy (notice I'm not talking about laparotomy - it would really be unnecessary just to make a diagnosis), and pulls out when he finds no disease, the death rate is as close to zero as you care to go. Essentially all of the less than 1 in 1000 complications and approx. 1 in 100,000 deaths from laparoscopy have occurred when actual surgery was performed, like a hysterectomy. That's getting down to the "hit by a car on the way to the hospital" range.
What percentage of false-positives would make it not worth doing the surgery?
From: the "Mench" "
Date: August 28, 2008 1:35:41 PM EDT
On Wed, Aug 27, 2008 at 4:46 PM, Fredrick wrote:
I would LOVE to see the artificial link between health insurance and employment broken, but even the casual observer knows it has to be accompanied by measures that take care of the high cost and cherry-picking of current private insurers. (Ideally by putting them out of the health insurance business altogether.)
To which Fredrick responded:
We can have an insurance type pool to share these high risk patients--it's called "community," as opposed to "experience" rating.
Moreover, if everyone were covered, then pre-existing conditions would not be as big a problem.
The weights to be applied to possible death versus certain inconvenience are very subjective, and I think should be the sole province of the patient - not the doctor, not the insurer, and not the government.
My own bias is that being able to avoid certain cancers is worth modest risk and discomfort. Some BRCA-positive women with high risks of breast cancer have even had prophylactic bilateral mastectomies. I don't find that irrational.
Having seen too many young post-menopausal women die from ovarian cancer discovered too late, and given that ovaries serve no significant function after menopause that can't be replaced with exogenous hormones (they're nothing but a pre-malignant mass of tissue), I've long advocated routine hysterectomy and bilateral oophorectomy and hormone replacement after menopause even in women with NO disease. (No, it wouldn't make me money - I don't do the surgery. It would have COST me money, since there would have been fewer cases for me to treat with radiation.)
Of course, no one does it, and no one besides me has even recommended it, in spite of the undeniable decrease in deaths from gyn cancers that would result. Some women scream at me for suggesting castrating them, but others would be delighted to be almost totally rid of the threat of ovarian, uterine, and cervical cancer.