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Patients and providers left with questions in the face of differing recommendations.

Government evaluation fuels debates over cancer screening guidance

Canada’s federal government is evaluating the effectiveness, structure, and processes of the Canadian Task Force on Preventive Care amid renewed debate over the timing of breast cancer screening.

The Task Force, which produces widely followed primary care guidelines, recommends shared decision-making for breast cancer screening and conditionally recommends against routine mammograms before age 50, stating the balance of benefits and harms is less favourable for younger patients.

However, the Canadian Association of Radiologists recommends that breast cancer screening should start at 40.

This past fall, Alberta split the difference, lowering the age for inclusion in its breast screening program to 45.

All this leaves some patients and their doctors uncertain about which advice to follow.

The debate spilled into federal politics during the last election. In response to campaign-time questions from patient advocacy groups, the Liberal Party committed to “review the structure of the Task Force to ensure that it incorporates the best advice and scientific evidence into its recommendations and guidelines.”

What’s the nature of the breast cancer screening dispute?

Disagreements between the Task Force and specialists over the breast cancer screening recommendations and other guidelines – including those for prostate cancer, hepatitis C, depression, cervical cancer, and lung cancer – boil down to differences in how each group weighs the evidence and handles the input of content experts.

“It goes down to what you do you value in a guideline,” says Michael Allan, Director of Programs and Practice Support at the College of Family Physicians of Canada, which endorses the Task Force guidelines. How a group balances bias, methodology, outcomes, harm versus benefits, and shared decision-making are subjective calls that understandably lead to differing advice, he said.

“How do you manage a potential bias versus the input of our specialist colleagues? It’s always been incredibly tricky,” Allan said.

On one hand, some specialists and patient advocacy groups argue that earlier detection saves lives. Some cite the findings of a non-randomized database study published in Current Oncology last year, which found that jurisdictions that screen people starting at age 50 had higher rates of breast cancer diagnosed at later stages than those where screening is provided for people in their 40s.

Data such as these prompted the Canadian Cancer Society, Rethink Breast Cancer, and the Canadian Breast Cancer Network to call on the Task Force to “review and examine all new and available evidence on breast cancer screening to determine if any changes or updates to current guidelines should be made.”

However, according to Task Force member Donna Reynolds, a family physician and former associate medical officer of health for Ontario, the overall benefits of screening remain modest, especially for people younger than 50, when weighed against the harms of false positives or diagnosing and treating cancers which might not have caused a problem otherwise.

“We don’t know which cancers will progress or not, and we don’t know if that cancer potentially regresses,” Reynolds explained.

A systematic review of patient preferences conducted by the Task Force, however, found that most women appeared to consider the benefits of reductions in breast cancer mortality to outweigh the risks of false positives and over-diagnosis – although the Task Force noted that many do not find this balance of benefits and harms acceptable.

Furthermore, Reynolds said guidelines developed by specialist groups have the potential for bias and conflicts of interest.

Members of the Task Force and specialist groups have accused each other of cherry-picking the evidence in letters published in CMAJ. Proponents of expanded preventive screening claimed the Task Force isn’t considering newer observational data, and the Task Force countered that such studies had mixed results and substantial biases.

“Other respected guidelines such as the USPSTF [United States Preventive Services Task Force] that did consider observational data found… that they did not impact recommendations,” the Task Force told CMAJ.

The USPSTF guidelines have also proven controversial, however, with the U.S. government imposing and extending a moratorium on the recommendations to protect coverage of screening for patients in their 40s.

Federal evaluation timeline

According to the Public Health Agency of Canada, the federal government will complete its evaluation of the Task Force’s effectiveness, structure, and processes by March 2023. A final report, as well as a management response and action plan, will be made public in April 2023.

“The Task Force welcomes this evaluation,” stated co-chair Ahmed Abou-Setta. “Task Force guidelines have been recognized as among the highest quality, and we welcome opportunities to continue to improve guideline creation and delivery… to ensure we’re doing this effectively.”

The federal evaluation comes as the Task Force will begin revisiting its breast cancer guideline in 2023. The group re-examines its recommendations every five years to determine if updates are needed.

Provincial health ministers established the Task Force in 1976 to provide independent advice, and “valuing objective research evidence over expert opinion” has been foundational to its impact.

Members are volunteers appointed jointly by Canada’s Chief Public Health Officer and the College of Family Physicians of Canada for their expertise in preventive health care, guideline development, and methodology.

The Task Force invites comments from content experts at multiple stages during guideline development, including help wording recommendations for clarity, but those experts do not vote on the final recommendations – a major point of contention among specialists who argue their clinical expertise should be given more weight.

“It’s true that there is a risk of bias [from specialist interests], but there is also a risk to lack of content expertise,” said Jordan Feld, past president of the Canadian Association for the Study of the Liver. “Both those risks are serious, and to assume that one risk completely outweighs the other risk is not appropriate.”

Specialists shut out?

Shushiela Appavoo, a radiologist and assistant clinical professor at the University of Alberta, said radiologists were invited to comment on an initial draft of the breast cancer screening guidelines in the early 2010s, but many felt their written comments and later feedback at a meeting were ignored. Appavoo and others also took issue with the Task Force conducting consultations on a 2018 update via email, which they felt limited opportunities for discussion.

Laurence Klotz, past president of the Canadian Urology Association, reported a similar experience when he and three other urologists provided feedback on the Task Force’s 2014 recommendations on PSA screening.

Klotz said that when they didn’t receive a direct response to their comments, he contacted the Task Force and was told they didn’t engage directly with stakeholders. Worried their participation would be interpreted as an endorsement, the urologists withdrew from the process.

“It should be an intense discussion and debate,” Klotz told CMAJ.

According to Klotz, the urologists’ feedback didn’t appear to be incorporated in the final guidelines, and despite withdrawing from the process, a Task Force presentation still appeared to reference their involvement.

Reynolds said the Task Force always considers stakeholder feedback, although it may not be incorporated in the final recommendations.

“If there are improvements to be made, we’ll make them,” she said. “It’s not something I’ve experienced where we’ve ignored people at all.”

According to the Task Force, if content experts provide input on a guideline but later withdraw from its development, they are still acknowledged for transparency reasons, as indicated at the outset of the process.

A Task Force procedural manual from 2011 stated the group would publish stakeholder comments and Task Force responses on its website. However, that version of the manual is not available on the Task Force website, and stakeholder comments are only available for the last three guidelines published in 2020 or later.

According to the Task Force, the group’s composition has changed completely since 2011, and a 2014 update of the manual doesn’t mention publishing stakeholder comments. Starting in 2019, the Task Force decided to publish stakeholder comments to increase transparency. However, “it could not be done retroactively due to privacy concerns.”

An updated version of the manual is under review and will be published in the coming weeks.

Alberta strikes a middle ground

Appavoo pointed to Alberta’s process as an example of how content experts and patients could be included in guideline development. That province’s panel on breast cancer screening included family physicians, an oncologist, a surgeon, radiologists, a diagnostic imaging technologist, public health physicians, a nurse practitioner, and a patient.

Participants were required to declare conflicts of interest, with the panel chairs deciding whether a conflict was significant enough to prevent an individual from participating.

“Anyone who is involved in breast cancer and has expertise in that area, their voices should be heard,” said panel co-chair Lisa Stevenson. “Everyone has a bias coming into it… but I think everyone really tried to come into it with an open mind.”

The panel considered the results of a literature search, guidelines in other countries, and provincial screening data, which showed that patients aged 45-49 were less than half as likely to be screened as those aged 50-54 but had nearly the same number of breast cancer diagnoses.

The panel also looked at modelling data which suggested that biennial screening starting at age 45 struck the best balance of benefits to harms while also being the most cost-effective.

Alberta’s process also considered newer observational studies  “that aren’t randomized controlled trials but are very well done,” Stevenson said.

Decisions were made by consensus.

Although specialists like Appavoo still promote earlier breast cancer screening starting at 40, she said Alberta’s process felt like an “honest compromise.”

“It didn’t feel like a token consultation,” Appavoo said. “I felt that we were heard.”

Editor’s note: CMAJ publishes Task Force guidelines. CMAJ’s communications strategist Kim Barnhardt also handles communications for the Task Force but has no involvement in news department decisions or content.

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