Abstract P1-10-01: Are physicians "choosing wisely" when imaging for distant metastases in women with early stage (1 or 2) breast cancer? A population study
Authors: Simos Demetrios , Catley Christina , vanWalraven Carl , Graham Ian D , Fergusson Dean , Arnaout Angel , Dent Susan , Clemons Mark 
Published: May 2015

Background: The probability of detecting radiologically evident distant metastases in asymptomatic patients with early stage (stage 1 and 2) breast cancer (BC) is low. Published guidelines, including the 2012 American Society of Clinical Oncology (ASCO) "Top-5" recommendation for "choosing wisely" in oncology, recommend against imaging in these patients. Imaging is also associated with significant false positive results and the need for additional confirmatory imaging and/or invasive procedures. Despite this evidence-base, imaging continues to be over-utilized. We decided to quantify the rates of staging imaging in women with early breast cancer in Canada’s largest province to determine whether provincial practice patterns are in keeping with the spirit of the guidelines and the 2012 ASCO "Top-5" recommendation.

Methods: Provincial registry data available through the Institute for Clinical Evaluative Sciences were used to identify all patients with a first diagnosis of stage 1 and 2 breast cancer who underwent breast cancer surgery. For each patient, all imaging of the most common metastatic sites (i.e. skeleton, thorax and abdomen) was captured from the date of diagnosis up until 3 months after definitive breast cancer surgery. Patients who received neoadjuvant therapy or with a prior history of any invasive malignancy were excluded.

Results: Between 2007 and 2012, 27,236 patients with stage 1 and 2 BC were identified. Overall data are shown in the table:

StageNo. of patients% having at least one imaging test (total)Total no. of imaging tests (mean per patient imaged)% of patients imaged who required confirmatory imaging (total)No. of confirmatory imaging tests performed (% of total imaging)114,11383% (11,713)40,464 (3.5)55% (6,420)11,202 (28%)213,12394% (12,330)53,729 (4.4)65% (7,983)16,292 (30%)

The most common initial (i.e. not confirmatory) imaging modalities of the skeleton, thorax and abdomen, for both groups were, bone scan (19%; 12,799/66,699), chest x-ray (28%; 18,789/66,699) and abdominal ultrasound (20%; 13,387/66,699) respectively. Use of advanced imaging (isotope bone scans, CT, MRI, PET) to look at potential sites of metastasis represented 38% (11,063/29,262) and 46% (17,180/37,437) of initial imaging tests in stage 1 and 2 BC patients respectively.

Conclusion: Imaging for distant metastatic disease in patients with stage 1 and 2 BC is commonly performed in Ontario despite multiple guidelines recommending against this. Advanced imaging (isotope bone scans, CT, MRI, PET) is commonly used as the initial imaging modality of choice. Of particular concern is the fact that 60% (14,403/24,043) of BC patients with early stage disease who were imaged required some form of confirmatory imaging. These results show the importance of the recent ASCO "Top-5" recommendation against staging imaging in such patients. The reasons for this disconnect between evidence and practice are not fully understood, but knowledge translation strategies beyond publishing guidelines or recommendations are required if we are to elicit a meaningful and sustained change in physician practice.

Citation Format: Demetrios Simos, Christina Catley, Carl vanWalraven, Ian D Graham, Dean Fergusson, Angel Arnaout, Susan Dent, Mark Clemons. Are physicians "choosing wisely" when imaging for distant metastases in women with early stage (1 or 2) breast cancer? A population study [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-10-01.