A new paper published this week in the Journal of Medical Screening suggests a Canadian study used to form breast screening guidelines around the world for decades is flawed.
Health
New paper casts doubt on trusted Canadian breast cancer screening guidelines
The Canadian National Breast Screening Study (CNBSS) started with two breast screen trials in 1980, and eventually involved tens of thousands of women in 15 Canadian urban centres. Investigators concluded that an annual mammogram for women aged 40 to 49 who are at average risk of breast cancer does not reduce the mortality rate any more than a physical exam.
As a result, Canadian researchers concluded that annual screening in women aged 40 to 49 at average risk does not reduce breast cancer mortality any more than a physical exam. Their findings were the basis for guidelines around the world that do not recommend annual screenings for women in that age group, including the most recent set put forth by the Canadian Task Force on Preventive Health Care.
I did not expect to find such clear, clear evidence of what was going on.
The risk of false positives and over-diagnosis is cited as a key issue in earlier screening. In such cases, even benign lumps would require a biopsy. Experts argue that radiation, chemotherapy or surgical treatment of breast cancer can be harmful, and that must be considered in treating a patient who might not even have it.
Dr. Jean Seely, co-author of the new paper and a professor of radiology at the University of Ottawa and head of breast imaging at The Ottawa Hospital, told CBC News there is “conclusive confirmation” the study was conducted with women — particularly in some locations — who were not randomly assigned.
She said when the authors of the paper interviewed 28 staff members who worked on the original study, some confirmed there were multiple instances in which women with detectable lumps, who were pre-screened by a nurse, were deliberately placed in the mammography group.
Debate has swirled around the studies since the results of the CNBSS were published. Critics have questioned the inclusion of women with advanced cancers, the quality of the screening participants received, and the factors used to determine whether mammograms were beneficial for women in their 40s. Experts have also voiced doubt about the randomization, though an investigation conducted by external experts failed to find “credible evidence” that it was subverted. Those investigators further said that if there were acts of subversion, they were few and their impact on the study’s findings trivial.
Seely hopes the evidence she and her co-authors presented in their paper lead to change.
“I think probably the most personal challenging moments that I have in my practice are when I see a woman in her 40s who presents with an advanced breast cancer,” she told CBC News. Most often, the patient was told by a family doctor that she didn’t need to be screened because of her age.
“On a personal level, as a professional, I find this very, very difficult,” Seely told CBC News.
Women aged 50 and older have higher rates of breast cancer diagnosis, according to the Canadian Cancer Society, but women between 30 and 49 with breast cancer are more likely to die from it. They represent 17 per cent of all cancer deaths in Canada, compared to eight per cent of women aged 50 to 69.
The study’s lead, Dr. Anthony Miller, a professor emeritus at the Dalla Lana School of Public Health at the University of Toronto, told CBC News, “We had a great deal of understanding of what could go wrong with randomization and we took a great deal of care to ensure it didn’t apply in the National Breast Screening Study.”
Miller told CBC News extensive quality-control measures maintained the integrity of the study, and he denies the possibility that any women were not placed randomly within the trials.
Seely and her co-authors have brought their concerns about the CNBSS to the University of Toronto and the Canadian Medical Association Journal, both of which were involved in the original study.
In a statement, the university’s office in charge of research, oversight and compliance said it is reviewing their concerns, and “places a high value on research integrity.”
The university did not specify details or a timeline of its review.
In her own statement to CBC News, Dr. Kirsten Patrick, interim editor-in-chief of CMAJ, said the journal “will co-operate with the university office’s process fully and will await the office’s report on the outcome of the review before deciding if any further action is needed.”
She did not provide any further comment.
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The Canadian government says it will donate up to 200,000 vaccine doses to fight the mpox outbreak in Congo and other African countries.
It says the donated doses of Imvamune will come from Canada’s existing supply and will not affect the country’s preparedness for mpox cases in this country.
Minister of Health Mark Holland says the donation “will help to protect those in the most affected regions of Africa and will help prevent further spread of the virus.”
Dr. Madhukar Pai, Canada research chair in epidemiology and global health, says although the donation is welcome, it is a very small portion of the estimated 10 million vaccine doses needed to control the outbreak.
Vaccine donations from wealthier countries have only recently started arriving in Africa, almost a month after the World Health Organization declared the mpox outbreak a public health emergency of international concern.
A few days after the declaration in August, Global Affairs Canada announced a contribution of $1 million for mpox surveillance, diagnostic tools, research and community awareness in Africa.
On Thursday, the Africa Centres for Disease Control and Prevention said mpox is still on the rise and that testing rates are “insufficient” across the continent.
Jason Kindrachuk, Canada research chair in emerging viruses at the University of Manitoba, said donating vaccines, in addition to supporting surveillance and diagnostic tests, is “massively important.”
But Kindrachuk, who has worked on the ground in Congo during the epidemic, also said that the international response to the mpox outbreak is “better late than never (but) better never late.”
“It would have been fantastic for us globally to not be in this position by having provided doses a much, much longer time prior than when we are,” he said, noting that the outbreak of clade I mpox in Congo started in early 2023.
Clade II mpox, endemic in regions of West Africa, came to the world’s attention even earlier — in 2022 — as that strain of virus spread to other countries, including Canada.
Two doses are recommended for mpox vaccination, so the donation may only benefit 100,000 people, Pai said.
Pai questioned whether Canada is contributing enough, as the federal government hasn’t said what percentage of its mpox vaccine stockpile it is donating.
“Small donations are simply not going to help end this crisis. We need to show greater solidarity and support,” he said in an email.
“That is the biggest lesson from the COVID-19 pandemic — our collective safety is tied with that of other nations.”
This report by The Canadian Press was first published Sept. 13, 2024.
Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.
The Canadian Press. All rights reserved.
HALIFAX – The Nova Scotia government says it could be months before it reveals how many people are on the wait-list for a family doctor.
The head of the province’s health authority told reporters Wednesday that the government won’t release updated data until the 160,000 people who were on the wait-list in June are contacted to verify whether they still need primary care.
Karen Oldfield said Nova Scotia Health is working on validating the primary care wait-list data before posting new numbers, and that work may take a matter of months. The most recent public wait-list figures are from June 1, when 160,234 people, or about 16 per cent of the population, were on it.
“It’s going to take time to make 160,000 calls,” Oldfield said. “We are not talking weeks, we are talking months.”
The interim CEO and president of Nova Scotia Health said people on the list are being asked where they live, whether they still need a family doctor, and to give an update on their health.
A spokesperson with the province’s Health Department says the government and its health authority are “working hard” to turn the wait-list registry into a useful tool, adding that the data will be shared once it is validated.
Nova Scotia’s NDP are calling on Premier Tim Houston to immediately release statistics on how many people are looking for a family doctor. On Tuesday, the NDP introduced a bill that would require the health minister to make the number public every month.
“It is unacceptable for the list to be more than three months out of date,” NDP Leader Claudia Chender said Tuesday.
Chender said releasing this data regularly is vital so Nova Scotians can track the government’s progress on its main 2021 campaign promise: fixing health care.
The number of people in need of a family doctor has more than doubled between the 2021 summer election campaign and June 2024. Since September 2021 about 300 doctors have been added to the provincial health system, the Health Department said.
“We’ll know if Tim Houston is keeping his 2021 election promise to fix health care when Nova Scotians are attached to primary care,” Chender said.
This report by The Canadian Press was first published Sept. 11, 2024.
The Canadian Press. All rights reserved.
ST. JOHN’S, N.L. – Newfoundland and Labrador‘s chief medical officer is monitoring the rise of whooping cough infections across the province as cases of the highly contagious disease continue to grow across Canada.
Dr. Janice Fitzgerald says that so far this year, the province has recorded 230 confirmed cases of the vaccine-preventable respiratory tract infection, also known as pertussis.
Late last month, Quebec reported more than 11,000 cases during the same time period, while Ontario counted 470 cases, well above the five-year average of 98. In Quebec, the majority of patients are between the ages of 10 and 14.
Meanwhile, New Brunswick has declared a whooping cough outbreak across the province. A total of 141 cases were reported by last month, exceeding the five-year average of 34.
The disease can lead to severe complications among vulnerable populations including infants, who are at the highest risk of suffering from complications like pneumonia and seizures. Symptoms may start with a runny nose, mild fever and cough, then progress to severe coughing accompanied by a distinctive “whooping” sound during inhalation.
“The public, especially pregnant people and those in close contact with infants, are encouraged to be aware of symptoms related to pertussis and to ensure vaccinations are up to date,” Newfoundland and Labrador’s Health Department said in a statement.
Whooping cough can be treated with antibiotics, but vaccination is the most effective way to control the spread of the disease. As a result, the province has expanded immunization efforts this school year. While booster doses are already offered in Grade 9, the vaccine is now being offered to Grade 8 students as well.
Public health officials say whooping cough is a cyclical disease that increases every two to five or six years.
Meanwhile, New Brunswick’s acting chief medical officer of health expects the current case count to get worse before tapering off.
A rise in whooping cough cases has also been reported in the United States and elsewhere. The Pan American Health Organization issued an alert in July encouraging countries to ramp up their surveillance and vaccination coverage.
This report by The Canadian Press was first published Sept. 10, 2024.
The Canadian Press. All rights reserved.
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