Abstract P5-01-01: Adding whole-body MRI to body CT scans when evaluating response to systemic anti-cancer therapies alters treatment decisions in metastatic breast cancer

Abstract

Abstract Introduction Accurate evaluation of disease extent and response to systemic anti-cancer therapy (SACT) is key to the clinical management of patients with metastatic breast cancer. By identifying disease distribution and response (particularly progression prior to symptomatic deterioration), imaging aids therapy choices and may maximise quality of life. Whole body MRI (WB-MRI) has increased accuracy for detecting liver and bone disease in breast cancer; however, its potential impact on patient management is largely unexplored. Thus, the purpose of this study was to evaluate the added value of WB-MRI with standard of care CT scans for clinical decision making in routine practice for patients with metastatic breast cancer. Methods All patients with metastatic breast cancer who had undergone WB-MRI between 1st April 2009 and 31st March 2016 were screened for this study. Those who had undergone a CT scan of the chest, abdomen and pelvis (CT-CAP) within 14 days of a WB-MRI date were eligible. Original radiology reports for the WB-MRI and CT-CAP were reviewed to establish the extent of reported disease and the SACT response assessment. Contemporaneous medical notes were reviewed to establish the impact of the paired imaging findings (and clinical review) with regard to therapy decisions per time point. Results 210 pairs of WB-MRI and CT-CAP scans in 101 patients were eligible for analysis. The median age of the studied patients was 56 years (range 23 to 84 years). 46 examination pairs were baseline studies; 164 were undertaken for response assessments (1st line SACT = 46; 2nd line = 27; ≥3rd line = 58; no information = 33). In 140 cases (66.7%) there were differences between the extent of disease reported by the WB-MRI and CT-CAP. Of these, 112 (80.0%) were due to the WB-MRI reporting additional sites of disease not evident on CT-CAP, mostly skeletal lesions. CT-CAP showed more disease in 10.0%, mostly lung lesions. 10.0% had some lesions evident only on WB-MRI and other lesions evident only on CT-CAP. Of the 164 scan pairs performed for SACT response assessment, there were differences in the reported response to therapy in 46 cases (28.0%). 89.1% of disagreements were due to WB-MRI showing evidence of either disease progression (67.4%) or partial response (21.7%) that was reported as stable disease on CT-CAP. Decisions to change SACT in response to disease progression reported by either/both imaging methods were made in 80 cases. Of these, treatment changes were made due to progression reported only on WB-MRI in 23 (28.8%) cases. Discussion This is a retrospective analysis of the real world use of WB-MRI and CT-CAP in the clinical practice of metastatic breast cancer, evaluating their impact on clinical care on a per time point basis. WB-MRI identified additional sites of disease (mostly bone) in over half of patients, which affected SACT decisions in a significant proportion of cases. In many cases, SACT changes would not have been made at the same time point without WB-MRI information. Further research is required to test the hypothesis that earlier identification of disease progression by WB-MRI leads to improved quality of life and patient outcomes. Citation Format: Kosmin M, Makris A, Joshi PV, Ah-See M-L, Padhani AR. Adding whole-body MRI to body CT scans when evaluating response to systemic anti-cancer therapies alters treatment decisions in metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-01-01.