Guest Post By: Brianne
People like cancer screening. It makes sense, we hear in the media about how it “saves lives” (other examples here and here). Sometimes, health care providers tell us that we need to do it “for our health”. The concept is appealing: we go to the doctor for a test, find out in 6 to 8 weeks whether everything looks normal or if we need more tests. What if cancer screening (also called early detection) doesn’t always do what we expect it to do?
The evidence of benefits of cancer screening is uncertain, and we’re increasingly aware of some of the harms of cancer screening . Incorrect test results (false positives or false negatives) or finding disease that won't actually impact one’s health can lead to physical, psychological, and financial harms for individuals and populations. So, when you’re deciding about participating in any type cancer screening, you and your health care provider can talk about the risks and benefits, and what is most important to you, before making a decision.
In Canada, cervical cancer screening programs aim to find pre-cancer and cancerous lesions so that they can be treated before any major health problems develop. Pap testing involves looking for abnormal cells on a sample that a health care provider collects during a pelvic exam. A new test – the HPV test – is being considered by Canadian screening programs to replace Pap testing, which involves looking for an infection of high-risk HPV on a sample collected by a health care provider. HPV testing can also be performed on a vaginal sample that a woman collects herself. These tests have different chances of having false positive or false negative results. Some of these options cannot be easily accessed either – they can only be purchased privately. Three different options for cervical cancer screening, all of which have different trade-offs between benefits and risks.
Different sample collection methods, different rates of false positives, different costs. How do you know what’s right for you?
As part of my research, my study team and I developed a website (www.screeningpreferences.com) that provides information on cervical cancer screening options that are available for women in Ontario. In the website, we clarify that women do face a decision in cervical cancer screening. We encourage individuals to explore information on cervical cancer, HPV, and screening.
Currently, women face a decision to participate in cervical cancer screening, or not. If they choose to participate, they can (hypothetically) choose between Pap testing, HPV testing on a sample collected by a doctor, or HPV testing on a sample they collect themselves. These options are described in more detail, along with some of the known risks and benefits. The final section of the website allows users to check their knowledge of the material, and asks users questions to help them see what is most important to them in choosing a preferred option. This part is important because different participants may value test characteristics differently. For example, some women may prefer to avoid a pelvic exam at all costs. Other women may want to do the test that their doctor recommends. Finally, the last section asks for feedback on the website: Was it useful? Is there any information that you think is missing?
Overall, the purpose for this website is two-fold: i) to help you choose your preferred cervical cancer screening option in an informed way, and; ii) to be used in later research to learn what cervical screening options populations of women prefer. This information will be useful for making cervical cancer screening better in the future.
We want to know what women think about using this tool. If you're interested, click the following link to explore the website and let us know your experiences:
We also encourage you to chat with your health care provider about different cancer screening options. They will help you figure out what options are available and what choice might be right for you.
 Prasad Vinay, Lenzer Jeanne, Newman David H. Why cancer screening has never been shown to “save lives”—and what we can do about it BMJ2016; 352 :h6080
Some other interesting references:
Patients overestimate the benefits of screening tests and underestimate the harms:
Hoffmann, T. C., & Del Mar, C. (2014). Patients’ Expectations of the Benefits and Harms of Treatments, Screening, and Tests. JAMA Internal Medicine, 175(2), 274–286. https://doi.org/10.1001/jamainternmed.2014.6016
So do doctors!
Hoffmann, T. C., Del Mar, C., Brandt, L., O’Leary, J., Iannone, L., & Waldhausen, J. (2017). Clinicians’ Expectations of the Benefits and Harms of Treatments, Screening, and Tests. JAMA Internal Medicine, 177(3), 407. https://doi.org/10.1001/jamainternmed.2016.8254
Here’s a recent high-quality review of cytology vs HPV testing (with a plain language summary):
Koliopoulos, G., Nyaga, V. N., Santesso, N., Bryant, A., Martin-Hirsch, P. P., Mustafa, R. A., … Arbyn, M. (2017). Cytology versus HPV testing for cervical cancer screening in the general population. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.CD008587.pub2
Brianne is a PhD student in Epidemiology at the University of Ottawa. She worked with Eve Medical on a Mitacs fellowship as part of her thesis to look at women’s preferences for cervical cancer screening options. She currently lives in Thunder Bay, Ontario. Feel free to contact her at email@example.com. She recently contributed to a news article about the future of self-sampling in Canada:
From time to time, we invite guest experts to share their professional opinions and thoughts on our blog. Views, opinions, and positions expressed within these posts are those of the author alone, and do not represent those of Eve Medical.