Quality and Efficiency of Staging Tests in Breast Cancer
The majority of Ontario women with early stage breast cancer undergo imaging for staging to detect metastases. Practice guidelines, however, do not recommend routine imaging to detect metastatic disease in patients with no symptoms. We have seen a small decline in the number of early stage breast cancer patients receiving these tests in the past few years. Efforts should continue to focus on improving awareness among physicians and patients and knowledge translation to increase guideline adherence.
Measure: Percentage of stage I breast cancer patients who received imaging tests to detect distant metastasis
As of this Report:
What type of tests are used for metastatic staging in breast cancer?
- Most women with a new diagnosis of breast cancer present with early stage disease (stages I and II) . In early stage breast cancer, the disease is confined to the breast tissue. This is in contrast to late stage breast cancer, where the disease has spread to other organs and tissues. These tumour deposits are known as metastases.
- Baseline imaging tests to detect metastases include bone scanning, liver ultrasonography, chest radiography (X-ray) and computed tomography (CT) [2, 3].
- The likelihood of tests detecting metastases in stage I or II breast cancer patients with no symptoms of spread are 0.2% and 1.2% respectively . For this reason, most guidelines (both national and international) do not recommend imaging for early stage breast cancer patients who have no symptoms of metastatic disease [2, 3].
- Imaging tests in patients without symptoms may identify findings unrelated to breast cancer that are of no clinical significance. This, in turn, may result in unnecessary further testing and needless patient anxiety.
- A disease pathway map for the screening and diagnosis of breast cancer outlines evidence-based best practices for when these and other tests should be ordered.
- Imaging equipment and resources to run the technologies are expensive and should be used appropriately whenever possible.
- In 2012, the American Board of Internal Medicine launched the Choosing Wisely® campaign with a goal of improving the dialogue around avoiding unnecessary or harmful medical tests, treatments and procedures. Choosing Wisely Canada (CWC) was promoted by a team of leading Canadian physicians in partnership with the Canadian Medical Association (CMA). CWC has endorsed the Choosing Wisely® recommendations and investigated additional opportunities to use resources more efficiently and effectively. For more information on CWC, visit http://www.choosingwiselycanada.org.
- In particular, Choosing Wisely® suggests the following:
- “Imaging with PET, CT or radionuclide bone scans can be useful in the staging of specific cancer types. However, these tests are often used in the staging evaluation of low-risk cancers, despite a lack of evidence suggesting they improve detection of metastatic disease or survival.”
- “In breast cancer, for example, there is a lack of evidence demonstrating a benefit for the use of PET, CT or radionuclide bone scans in asymptomatic individuals with newly identified ductal carcinoma in situ (DCIS), or clinical stage I or II disease.”
- “Unnecessary imaging can lead to harm through unnecessary invasive procedures, over-treatment, unnecessary radiation exposure and misdiagnosis.”
What is efficiency?
- Efficiency is a dimension of health service quality that tracks whether we are making the best use of our existing resources (such as types of treatment, machines, staff and hospital beds) to achieve desired outcomes.
- The results tell us about the proportion of patients being treated according to guidelines. They also help us consider the utilization of these unique technologies in order to identify whether they are being used to their maximum potential—or whether there is opportunity to better use the capacity of a limited resource for those patients who need it most.
What do the results show?
The number of patients receiving unnecessary tests (as defined by guidelines) is higher than expected and includes regional variation (Figures 1 and 2).
- Figure 1 shows that the majority of women diagnosed with early stage breast cancer may be receiving unnecessary imaging tests for staging. The average number of stage I patients receiving these tests has decreased slightly each year since 2012, the year Choosing Wisely® was launched.
- Women with stage II breast cancer are undergoing more tests than women with stage I breast cancer. This may partly be due to variations in guideline recommendations: the current Cancer Care Ontario guidance document indicates bone scanning for stage II patients , but Choosing Wisely® does not recommend this test .
- Modalities included in this analysis are ultrasound, CT, X-Ray, and bone scan. These tests were performed on any of the following: skeleton, thorax (excluding pre-operative chest X-ray) abdomen, and pelvis.
- Some early stage breast cancer patients will present with symptoms and comorbidities that require staging tests. Clinical consensus and recent evidence says that these patients only account for 5% to 10% of the early stage breast cancer population , yet in 2016, 47% of stage I patients received imaging tests for staging. Of the 3,957 distinct tests performed on stage I patients in 2016 (data not shown), 3,561 (90%) may have been unnecessary.
- Figure 2 shows that in 2016, the proportion of stage I breast cancer patients who had staging tests for metastatic disease showed some regional variation (from 35% to 60%). A similar range was seen in the previous two years: 2015 (from 40% to 65%) and 2014 (from 44% to 74%). However, the regional rankings vary between the years and there is no clear region with best or worst practices.
- The reasons for a discrepancy between guideline recommendations and practice are likely a combination of patient-related and physician-related factors. Patients have reported that additional testing gives them peace of mind and that they would be uncomfortable if their doctor, in concordance with the local Cancer Care Ontario guidelines, did not perform imaging for metastatic disease [3, 5]. Physicians, however, have reported that clinical findings or suspicious clinical history is what prompts referral for staging tests (as opposed to patient preference) .
- The cost of each scan depends on the modality, and it includes a physician fee, technician fee and facility overhead costs. A CT scan of the abdomen, for example, costs around $219 ($108.30 (X126: CT abdomen, with or without IV contrast) ; $18.50 (NOC 3215: medical radiation technologists median wage $37.00; assume 0.5hour for CT ); $92.54 (institutional internal overhead cost) to the system[8, 9]. A recent study published in the journal Current Oncology found that the cost of all imaging on early stage breast cancer patients in Ontario ranged from $4.4 million to $6.8 million over a 5-year period, depending on guideline recommendations (figures are cumulative and in Canadian dollars).
- These tests have downstream implications on the system because they may lead to follow-up examinations and (in the case of false positive tests) unnecessary treatment. If unnecessary tests were eliminated, it might increase test availability for other patients.
- As of December 2017, the median adult wait times in Ontario for patients with known or suspected invasive cancer (non-aggressive, non-emergency) were 13 days for CT scans and 13 days for MRI scans. 63% of patients were scanned within the target time of 10 days .
Why is this important for patient care?
Appropriate testing is a quality issue and a limited system resource issue.
- One of the main purposes of staging is to rule out metastasis. Staging may occur before surgery, but it is more commonly performed after surgery at the hospital where primary therapy is given .
- Staging tests are time-consuming and anxiety-provoking. Occasionally, false-positive results lead to other expensive tests. Unnecessary imaging can lead to harm through unnecessary invasive procedures, over-treatment, unnecessary radiation exposure and misdiagnosis .
- Each test is associated with a wait time. Unnecessary testing delays definitive treatment (surgery or systemic) and is not likely to provide benefit to the patient.
- Imaging is a limited resource. Increases in use of diagnostic imaging in Canada have far exceeded population growth: from 1993 to 2004 there was a 3-fold increase in the number of CT scans and a 7-fold increase in the number of MRI scans . The high demand for these services contributes to longer wait times. When patients who do not need a test are removed from the queue, there is more timely capacity for those patients who do need the tests.
How does Ontario compare?
- An Ontario study, published in the Canadian Medical Association Journal in 2015, demonstrated similar results presented here . Overall, there was a higher imaging utilization rate (86%) for early stage breast cancer patients (stage I and II) than those presented in this section (62% of stage I and II patients). The lower numbers reported in the Cancer System Quality Index (CSQI) may be attributed to the exclusion of pre-operative chest X-ray from these data (as per the CWC anesthesiology recommendations) . The Ontario study in the Canadian Medical Association Journal also assessed data from 2007 to 2012, prior to any effects that the Choosing Wisely® recommendations would have had on diagnostic testing. The CSQI data analysis took a conservative approach by including only the most common forms of breast cancer, and excluding those unusual pathologic subtypes that could be associated with a higher risk of distant metastases.
- A study from the United States demonstrated that only 15% of early stage breast cancer patients from 2 separate facilities had at least 1 imaging test during the staging window. Investigators conducted chart-level audits and found that approximately half of the imaging tests were ordered in response to a sign or symptom .
- A Canadian study assessed the consistency of radiological staging for breast cancer in an academic oncology setting and found that 59% of stage I patients and 58% of stage II patients were over-investigated. The study estimated that the cost of non-adherence is in the range of $78 (Canadian dollars) for every new early stage breast cancer patient who is seen at the centre .
Find out more
For more information on Cancer Care Ontario’s Disease Pathway Map for patients with breast cancer, visit Cancer Care Ontario’s website: https://www.cancercareontario.ca/en/pathway-maps.
For more information on the Imaging Program, visit Cancer Care Ontario’s website: https://www.cancercareontario.ca/en/cancer-care-ontario/programs/clinical-services/cancer-imaging.
For more information on Choosing Wisely®, visit: http://www.choosingwisely.org/ .
For more information on the Choosing Wisely Canada initiative, visit: http://www.choosingwiselycanada.org/ .