Mailed HPV tests can help find women at-risk for cervical cancer, study finds
Our Review Summary
The release focuses on a recent “proof-in-principle” study that found it is feasible to use at-home testing kits to screen low income women with limited access to medical care for human papillomavirus (HPV) infection, which can lead to cervical cancer. The release could do more to clarify the sensitivity and specificity of the screening tools, but does a good job of making clear that more work needs to be done before this approach could be deployed on a broad scale.
Why This Matters
As the National Cancer Institute notes, virtually all cervical cancers are caused by HPV — with most of them being caused by certain strains of HPV. And early diagnosis of HPV infection can help to prevent cancers, or allow patients and healthcare providers the warning they need to monitor for cervical cancer. That makes screening for HPV important, and especially so for patients with limited resources who may not have regular access to healthcare providers for screening or regular check-ups. And those at-risk communities are precisely who this study was trying to address. It’s important to make clear — as this release does — that cost remains a challenge, and that regulatory barriers remain. Most importantly, the release stresses that more work needs to be done before this approach to screening moves from theoretical to practical.
The release does not place a pricetag on HPV screening — which would include the test kit, analysis and follow-up clinical visit. However, the release does explicitly say that “there is more work to be done, such as identifying ways to make the self-collection process more efficient and cost-effective.” That acknowledgment is enough to earn it a satisfactory rating here.
This is a tricky question, as it is not clear how one should define the relevant benefit. The paper itself defines the goal of the study as evaluating the “validity and acceptability” of at-home self-collection of samples for HPV screening. If part of assessing “acceptability” was determining whether mailing self-collection kits improved screening rates, should the benefit be defined as successfully submitting a sample for screening? If so, the release failed, since it doesn’t even tell readers how many women received screening tests through the mail (284 women, according to the related paper). However, validity is easier to address. How well did the at-home, self-collected samples compare to other screening tests? The release does address this head on. It states that the at-home, self-collected test indicated 12.4% of women had high-risk HPV infections. In-clinic, self-collected tests indicated 15.5% had high-risk HPV infections. And clinician-collected tests indicated 11.4% of women had high-risk HPV infections. Those are hard numbers, and we’ll give the release the benefit of the doubt on this one. However, those three different numbers raise some questions, which the release doesn’t do a good job of addressing. More on that below.
The release did not address two key potential harms, namely the failure to identify someone who has high-risk HPV, and the “false positive” misdiagnosis of people who did not have high-risk HPV. This is the difference between “sensitivity” and “specificity.” It’s particularly relevant in this instance because HPV screening has a track record of problems with both specificity and sensitivity— and because the release itself makes clear that there were people diagnosed as at high risk in some of the screening tests, but not others. Missing someone who is at high risk is clearly problematic. But being told that one faces significant medical risks that one does not actually face can also have ramifications for future healthcare, with consequences both physical and financial.
Another potential harm could be having a certain rate of patients sending in the test but not following up, leaving clinicians with positive tests and patients lost to follow up which would skew the impact of the screening effort.
This boils down to a very simple problem: the release gives readers key information and then fails to explain it. This concern is in regard to the lack of comparison in screening results across three types of tests: at-home, self-collected tests indicated 12.4% of women had high-risk HPV infections; in-clinic, self-collected tests indicated 15.5% had high-risk HPV infections; and clinician-collected tests indicated 11.4% of women had high-risk HPV infection.
To most readers, the difference between 11.4% and 15.5% seems like a lot — more than 4%. If they were to do the math at home, they’d see that eight people (out of 193) were diagnosed as being at high risk in one scenario, but not in another. What gives? But the release only addresses this with a quote saying “We found comparable detection between self-collection and physician-collection.” That’s not helpful. In addition, the release refers more than once to the fact that “all women found to have high-grade cervical lesions…were positive for high-risk HPV in their home self-collected sample.” But the release doesn’t tell them that this group consisted of fewer than 10 people, or the extent to which that may be extrapolated to a larger population. In short, it’s important to address sensitivity and specificity when writing about a diagnostic tool.
HPV — particularly certain strains of HPV — can significantly increase risk for cervical cancer. There’s no doubt about that. However, not all women who contract HPV will get cervical cancer. There’s no doubt about that either. In fact, the CDC notes that 80 percent of women have contracted HPV by the time they are 50, yet the National Cancer Institute estimates that less than one percent of women will contract cervical cancer in their lifetime. It can be difficult to highlight the importance of HPV screening without edging into “disease mongering” territory. This release walks up to the line, but doesn’t cross it.