The Rap on Pap Tests
And a cervical screening approach that actually does make sense
Not too long ago I received a letter from my Canadian provincial cervical screening registry informing me that it had been three years since my last Pap test, and since Pap tests save lives, I should book an appointment for one.
I am 48 years old. I am a gynecologist. I should know better. But that’s the problem; I DO know better, and what I know has eroded my confidence in this cancer preventive tool.
Pap tests do save lives. In the past, it has worked well as a screening tool. However, recent changes in screening guidelines stand to make it less reliable. Here’s why.
If you have at least a CIN 2—a moderate to severe dysplasia that can progress to cancer in 20% of women—the probability that a single Pap test will pick up the lesion is only 53%. In other words, 47% of these lesions will be missed.
In the old days of annual Pap tests, a CIN 2 might have been picked up the next year, or maybe the year after. But with our new screening guidelines, you have to wait three years for your next Pap, and at that visit there is the same 50/50 chance it will be missed. Fast forward three years and you can see how some women might get caught up in a vicious cycle, with dangerous consequences.
I know that if I have a CIN 2 or greater lesion, 50% of the time my Pap test will be normal. So what does a normal Pap test mean to me? Nothing. Hope for the best and come back in three years!
But there is something women can do to improve the health odds. Many countries now do high risk HPV (hr-HPV) testing at the same time as Pap testing (called co-testing). A negative co-test (negative Pap and negative hr-HPV) actually means something. It allows you to confidently wait for five years for your next screening. A negative Pap with a positive hr-HPV test allows you to be screened again in one year—increasing the detection of pre-cancerous lesions. The science is sound, and it is easy!
In April, the US Food and Drug Administration approved the first HPV for primary cervical cancer screening. The so-called cobas HPV Test is used to identify HPV DNA from 14 high-risk genital HPV types that are commonly associated with cervical cancer. It specifically identifies types HPV 16 and HPV 18 while at the same time detecting the rest of the high risk types. If the test results are positive, the patient is likely infected with HPV. By recognizing the validity of the screening tool, the FDA opened the door to insurers covering the cost of the test.
Two months later, Health Canada, which sets regulations on the use of drugs and devices, did the same and approved the cobas test as a first-line primary screening test for cervical cancer.
But not all countries are making it easy for women to access the tool. In the end, it comes down to money. In spite of models showing that the strategy of co-testing is actually more cost-effective than current screening, there is a “change-over” or start up cost to this approach. And this cost is not currently a health care priority for most governments!
Hr-HPV testing can be offered as a non-insured service, payable by the patient. This would allow those with expendable income (the test costs about $100) to choose to spend it on a superior class of health care. We are already doing this with some vaccines and medications, so why not with this? If this test is available, shouldn’t women be offered the option to pay for it?
By the way I finally made that appointment for a Pap test. And I got an hr-HPV test done at the same time. The cost to me was US$90.