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Study reveals widespread over-imaging in early stage breast cancer patients in Ontario

June 22, 2015

Reducing unnecessary imaging could improve care and reduce costs




Researchers at The Ottawa Hospital and the University of Ottawa have found that most Ontario women with early stage breast cancer are undergoing unnecessary imaging to determine if their cancer has metastasized (spread) despite international and provincial guidelines which recommend against the practice. The study, published in the Canadian Medical Association Journal (CMAJ) on June 22, 2015, is the largest ever to examine breast cancer imaging in Canada.

The results are based on a review of medical records of more than 26,000 women treated for early-stage breast cancer in Ontario between 2007 and 2012 and include more than 83,000 imaging tests. The records were obtained through the Institute for Clinical Evaluative Sciences (ICES) database.

The study shows that nearly 80 percent of patients with Stage 1 breast cancer and more than 90 percent of patients with Stage 2 cancer had unnecessary tests according to guidelines set out by Cancer Care Ontario, the American Society of Clinical Oncologists, and the National Comprehensive Cancer Network, among others.

“Breast cancer is the most common cancer in women and the incidence is rising as the population ages,” said Dr. Mark Clemons, senior author of the study and an oncologist and associate scientist at The Ottawa Hospital and the University of Ottawa. “The good news is that most women are presenting early with small, highly curable cancers that have not spread. So the chances of a scan picking up the spread of breast cancer in Stage 1 and Stage 2 is incredibly low,” he explains. “And that is why the guidelines recommend against imaging at these stages of the disease.”

The literature is clear in showing that only 0.2 percent of patients with stage 1 breast cancer and 1.2 percent of patients with stage 2 breast cancer have metastases that can be detected by x-ray imaging; as such most patients who present with early stage breast cancer would not benefit from getting these tests.

The study found that close to a quarter of the patients with Stage 1 and Stage 2 breast cancer who had unnecessary imaging done ended up having additional tests because of false positive findings.
“It is in a sense a double whammy,” said Dr. Clemons. “Patients who had inappropriate tests were subjected to secondary tests that were also unnecessary. All these tests produce harm for our patients—they produce anxiety, stress, expose patients to radiation, delays in required treatment, and can lead to overtreatment and bigger surgeries.”

Dr. Clemons and his colleagues are now investigating barriers that may be preventing the guidelines from being followed by both health-care providers and patients. Currently research is being done at The Ottawa Hospital to help patients and doctors identify strategies to reduce over-imaging.

Dr. Angel Arnaout, also a co-author of the paper and a surgical oncologist and associate scientist with The Ottawa Hospital and the University of Ottawa, notes that The Ottawa Hospital is a pioneer in supporting this type of research on best practices and knowledge translation.

“This is research that has a direct impact on patients and that is what we are all about,” explains Dr. Arnaout. “It is win-win information really and needs to be shared. We as physicians care about doing the best for our patients; but doing more isn’t always better.”

It is estimated that following imaging guidelines for early stage breast cancer could result in a savings of at least $3.4 million annually to the provincial health care system.

The paper, titled “Imaging for distant metastases in women with early stage breast cancer. A population-based, cohort study”, was published by CMAJ on June 22nd, 2015, and is authored by Demetrios Simos, Christina Catley, Carl van Walraven, Angel Arnaout, Christopher M. Booth, Matthew McInnes, Dean Fergusson, Susan Dent, and Mark Clemons.

This research was supported by the Patient Quality & Safety Committee of Ottawa’s Department of Medicine and the Division of Medical Oncology, University of Ottawa and The Ottawa Hospital Foundation.

Ottawa Hospital Research Institute


The Ottawa Hospital Research Institute is the research arm of The Ottawa Hospital and is an affiliated institute of the University of Ottawa, closely associated with its faculties of Medicine and Health Sciences. The Ottawa Hospital Research Institute includes more than 1,700 scientists, clinical investigators, graduate students, postdoctoral fellows and staff conducting research to improve the understanding, prevention, diagnosis and treatment of human disease. Support our research. Give to the Tender Loving Research campaign.

For further information, please contact


Lois Ross
Senior Communications Specialist
Ottawa Hospital Research Institute
Office: 613-737-8899 x73687
Cell: 613-297-8315
loross@ohri.ca