Most provincial, national and international guidelines do not recommend X-rays for those with early stage, operable breast cancer with no symptoms, because the likelihood of a scan picking up evidence of the cancer spreading has been established in medical literature as extremely low.
Dr. Mark Clemons, an oncologist and scientist at the Ottawa Hospital, and his team investigated whether doctors and their patients played it safe and did imaging anyway.
For 26,547 women with Stage 1 or Stage 2 breast cancer diagnosed between 2007 and 2012, the answer was mostly yes: 85.9 per cent had at least one imaging test, such as an X-ray, bone scan, ultrasound or CT scan, Clemons and his colleagues report in Monday's issue of the Canadian Medical Association Journal.
"Apart from wasting resources, is there really any harm in doing any imaging just in case? There is," Dr. Matthew Stanbrook, deputy editor for CMAJ, said in a podcast.
"Not only is such imaging costly, it doesn't prolong survival in this context."
Tests 'reflexive' on part of doctors
Dr. Daniel Rayson, a medical oncologist at QE II Health Sciences Centre in Halifax, is one of the authors of a commentary published with the study.
"Mostly it due to a reflexive testing strategy by surgical oncologists and medical oncologists and perhaps not spending the time we need to spend with each individual woman talking about the downsides of all of these tests," Rayson said in an interview, when asked why the guidelines aren't followed.
Dr. Sunil Verma, a medical director at the Louise Temerty Cancer Centre at the Odette Cancer Centre in Sunnybrook Health Sciences in Toronto, said the findings serve as a reminder to follow the guidelines in conversation with patients. He was not involved in the research.
"The biggest downside is if somebody goes through these tests we may find a small little nodules which is irrelevant and it requires us to do some more tests and more biopsies, so there are complications that may arise, there are delays that may happen" that affect treatment, Verma said.
In the study, 80 per cent of the patients were at least 50 years old.
In the study, imaging was more likely with younger age, other illnesses, axillary node involvement or if surgery was done in a community hospital. For some of these variables, there is "no biological rational for increased imaging," the study's authors said.
MJ DeCoteau, executive director of Rethink Breast Cancer, which focuses on women under age 40, said she wasn't overly surprised by the findings, given how much fear surrounds cancer, which she said can overshadow evidence.
"We hear woman talking about scanziety," DeCoteau said. "They want to have the scan done. They want to know what is going on. They want the information, but at the same time it terrifies them."
The researchers acknowledged they couldn't determine the specific indication why doctors ordered imaging, which could have been for reasons besides breast cancer staging.
They also couldn't tell whether patients were free of symptoms, although they noted the literature and clinical experience suggests most patients having surgery for newly discovered breast cancer are asymptomatic.
No one knows yet if the findings apply across all provinces and territories.
The study was funded by the Patient Quality and Safety committee at the University of Ottawa's medicine department.