In Favor of Co-Testing

Recently, Lablogatory interviewed R. Marshall Austin, MD, PhD, in regards to the benefits of using both liquid-based cytology and HPV testing to screen for cervical cancer. The interview below has been lightly edited for brevity and clarity.


 

Hi, Dr. Austin. Thanks for joining us today. Can you tells us a bit about your background?

I consider myself a gynecological pathologist, which includes surgical pathology and cytology. I’ve been involved with cervical screening issues for quite some time. Going back to the 90s, and even before that with CLIA ’88. My PhD is in virology, which is relevant now with the all the HPV issues. I did my subspecialty training in GYN and breast pathology and cytology at the armed forces institute of pathology.

Over your career you’ve authored or co-authored over 80 papers relating to cervical cancer screening. What made you so interested in this field of study?

It was an area that became a hot topic with CLIA ’88. CLIA ’88 was precipitated by a Wall Street Journal expose on Pap smear screening in the United States, which was ironic because the Pap smear has been the most effective cancer screening test in the history of medicine. This drew me in, since it was my subspecialty area of interest. There had been technological advances in the field even though the Pap smear itself hadn’t changed that much since it was introduced during World War II. Computer-assisted screening, liquid-based cytology, HPV testing all really have dramatically changed the field.

What was your initial reaction when the US preventative services task force released their draft document on cervical cancer screening recommendation in September of 2017?

I thought it was a mistake. I wrote a letter why I thought so, and apparently a lot of other people did, too.

How integral was the pathology and medical community’s reaction to this draft document in changing the USPSTF’s recommendations to include co-testing?

I’m sure that the feedback had a cumulative impact. I’ve heard different views on what components were most instrumental.

What made you decide to perform the recent study that appears in AJCP?

I had read online at the end of last year a pre-publication paper published by the Journal of the National Cancer Institute. I had seen their figures presented by Walter Kinney as early as October at a meeting in Amsterdam. I asked him where these figures available, and he said they were going to be published. I thought their results were probably different than what we would have seen in our own lab. So I thought we really need to look at our own data in the exact same format as the data presented in the JNCI. We were able to do that by about March.

Wow! That seems really fast, considering how large your data set is.

We have kind of an unusual set up here because I work with two information scientists here at the University of Pittsburg. We automatically have all of our data being taken from our LIS into a cervical screening model which we call the Pittsburgh Cervical Cancer Screening Model and we have over 13 years of data. So we’re in kind of a unique position to very quickly put our data into different types of formats. Agnieszka Onisko, the information scientist on the publication, was able to quickly look at our data and get it into the same format as the paper from Kaiser. Once I saw how different our results actually were, my goal was to get the paper out before the USPSTF report came out. We had our tables and figures by March and I submitted the manuscript to AJCP in early May.

Let’s talk a little bit about the benefits of cotesting, and some of the downsides.

Well, the reason I always tell people, the reason that women get screened is because they don’t want to get cancer and they don’t want to die of cancer. Getting screened isn’t a pleasant experience, necessarily, but women don’t get screened because they’re worried about dysplasia or some other condition. They’re worried about cancer. The other thing that’s always been misunderstood is the limitations of screening. Screening was effectively sold to the American public by the American Cancer Society and the National Cancer Institute, and while it was an effective campaign, it basically left women with the impression that if they get screened, they won’t get cancer. Although cervical cancer screening has been the most effective cancer screening program ever, it’s never been perfect. A paper out of England in 2016 had a sophisticated analysis about the effects of cytology screening on cancer rates in England. It estimated that about 70% of cancer mortality was being eliminated with screening, and could potentially be as high as 83%, which still isn’t 100%. So when women get cancer, they get upset. My general philosophy has always been that we should do as much as we can to minimize cancer in the screened population because that’s what the public wants and expects.

The disadvantages of cotesting is one, it adds costs. Two tests cost more than one, after all. And also, cotesting adds the potential for more red flags that require potential investigation that can increase the number of procedures. Having said that, and having been involved in a number of years especially in cases where litigation is involved the public wants and expects the most protection possible. So, to me, the extra cost is still in line with what the public wants: the maximal possible protection.

The Law of Unintended Consequences

Has the guidelines that encourage less Pap testing over the course of a woman’s life contributed to less women being screened for STDs such as Chlamydia? According to a study published this week, yes.  The cohort is rather small–3000 teenagers and young women–but even so, the results are striking. Before 2009, 30 percent of patients were screened for Chlamydia; after 2009, only 1 percent were.

While this is discouraging, the CDC found that teenagers are having less sex than they were twenty-five years ago, which some attribute to the HPV vaccine and its accompanying education.

Further reading on the relationship between HPV vaccines, Pap screening, and STD testing:

Chicago Tribune

NPR

Healthday

Swails

Kelly Swails, MT(ASCP), is a laboratory professional, recovering microbiologist, and web editor for Lab Medicine.