369P - Metabolic tumour volume by 18F-FDG PET/CT is an independent prognostic factor in metastatic breast cancer

Abstract

BackgroundMetabolic tumor volume(MTV) measured by (18)F-fluorodeoxyglucose positron emission tomography/computed tomography(FDG PET/CT) was correlated with prognosis in various cancers. The aim of this study was to investigate the prognostic value of MTV in metastatic breast cancer (MBC). MethodsWe retrospectively reviewed 172 patients who underwent FDG PET/CT at diagnosis of MBC at a single center. MTV for the whole body tumor lesions were measured by FDG PET/CT. The prognostic significance of MTV and other clinicopathological variables for progression free survival (PFS) to the first line palliative treatment(1L-PFS) was assessed by Kaplan-Meier method and Cox proportional hazards regression analysis. ResultsMedian age was 45 years (range 27-71). 76 patients had hormone receptor-positive(HR+)/human epidermal receptor-2 negative(HER2-) disease, 55 patients had HER2+ and 41 patients had triple negative breast cancer(TNBC). In the univariate analysis, TNBC subtype and higher MTV was associated with worse 1L-PFS. On multivariate analysis adjusted for age, presence of visceral metastases, and liver involvement, indepent predictive factors associated with decreased 1L-PFS were TNBC (HR 2.724 versus HR+/HER2 subtype, p=0.002) and MTV (HR 1.165 with doubling of MTV, p=0.001). ConclusionsMTV, a volumetric parameter of FDG PET/CT, is an important independent prognostic factor for PFS to the first line palliative treatment, irrespective of tumor subtype, in patients with MBC. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureY.H. Park: Advisory / Consultancy, Research grant / Funding (self): AstraZeneca; Advisory / Consultancy, Research grant / Funding (self): Pfizer; Advisory / Consultancy, Research grant / Funding (self): Eisai; Advisory / Consultancy, Research grant / Funding (self): Novartis; Research grant / Funding (self): Roche. All other authors have declared no conflicts of interest.