This guideline is one of a set developed by the Program in Evidence-Based Care's (PEBC) Diagnostic Imaging Guidelines Panel, using methods adapted from the Practice Guidelines Development Cycle. These guidelines are intended to:
- Promote evidence-based practice
- Provide guidance to clinicians about which imaging techniques are the most appropriate to use in the workup and management of their patients
- Provide information that is useful to those charged with planning for the number of imaging machines needed for patients with cancer in Ontario
- Assist in monitoring the use of imaging modalities in patients with cancer
Panel members included medical, radiation, and surgical oncologists; diagnostic radiologists; and methodologists. Prior to embarking on the guideline development, members were asked to disclose information on any potential conflicts of interest, but there were none. The PEBC is editorially independent of Cancer Care Ontario and the Ontario Ministry of Health and Long-term Care.
The Diagnostic Imaging Guideline panel:
- Formulated a set of guideline questions relevant to cancer care in Ontario
- Systematically reviewed existing evidence-based guidelines and evidence from primary studies
The Breast Working panel:
- Considered the quantity, quality, consistency, completeness and relevance of the available evidence
- Drafted recommendations
- Consulted members of relevant PEBC Disease Site Groups and external reviewers for feedback
Evidence and expert opinion were considered in determining whether imaging should be conducted (e.g., How often would diagnostic imaging with computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (US) revise staging in patients with cancer?) and then which imaging test would be most appropriate (e.g., Should CT, MRI, or US be used to detect liver metastases?). An informal consensus process was used to reach agreement on recommendations.
A focused external review process was planned for each document, utilizing the expertise of a small panel of experts. That was obtained through a mailed survey consisting of items that addressed the quality of the draft report and recommendations and whether the recommendations should serve as a practice guideline.
How often would diagnostic imaging with computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound revise staging in patients with newly diagnosed cancer?
Imaging to detect metastatic disease
The guideline panel considered the role of staging in breast cancer at diagnosis to be effectively dealt with by the PEBC guideline. However, two issues were not directly assessed in that original guideline. First, there is no evidence to help determine what blood work is needed preoperatively in patients undergoing breast cancer surgery. Generally, that would be decided by each local hospital in accordance with the anesthesia requirements and general health of the patient. The second issue involves patients found to have clinical stage III cancers preoperatively, a group not commonly seen now because of more aggressive screening and increasing breast cancer awareness. They can be assessed in the same way as other patients with earlier stage disease. If they are clinically operable, surgery is still usually the best initial approach unless there are features in their physical exam that would suggest inoperability. If surgery is not felt to be initially possible then referral to a multidisciplinary clinic consisting of a general surgeon, radiation oncologist, and medical oncologist is advised to determine their optimal management. At that clinic, they would be staged through a bone scan, abdominal ultrasound, and a chest radiograph. Although diagnostic imaging tests continue to evolve rapidly, there is, unfortunately, no conclusive evidence to support changing the approach discussed above.
Imaging to determine extent of disease in the breast
Limited evidence was identified on the use of imaging to determine the extent of disease in the breast, and some of the evidence was contradictory. In general, ultrasound was found to have a relatively low sensitivity and high specificity, with the exception of one study. Mammography was similar to ultrasound in performance. MRI was generally found to have high sensitivity and good specificity. The weight of the identified evidence is in favour of MRI for the detection of multifocal or diffuse disease.
In what circumstances and with what frequency would diagnostic imaging with CT, MRI, or ultrasound be useful in determining tumour response in patients undergoing chemotherapy or radiotherapy?
Only evidence that evaluated chemotherapy in the neoadjuvant setting with regard to detecting tumour response was available. No studies were identified addressing chemotherapy in the adjuvant or metastatic setting or radiotherapy. In the neoadjuvant studies, both the clinical examination and MRI had generally high specificity. Clinical examination had a generally low sensitivity (11% to 39%), while MRI had widely varying sensitivity (0% to 100%, median 74%). That wide variation in sensitivity for MRI was not immediately explained through this review of the studies.
What is the role of CT, MRI, and ultrasound in the detection of recurrent disease during the follow-up of patients who have completed primary treatment for cancer, and what should be the frequency of use of those tests during follow-up?
No evidence beyond existing systematic reviews and guidelines was obtained for this review. The Diagnostic Imaging Guidelines Panel endorses the recently updated Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer guideline.
What is the role of CT, MRI, or ultrasound in assessing patients who develop symptoms of disease recurrence or elevated biochemical markers after primary treatment for cancer?
Only one study was identified that looked at imaging modalities in assessing patients who developed symptoms of disease recurrence. The randomized controlled trial (RCT) did not detect a significant difference between CT and MRI.
