Clinical and imaging-based prognostic factors in radioembolisation of liver metastases from colorectal cancer: a retrospective exploratory analysis

Kathy P Willowson; Aimee R Hayes; David L H Chan; Michael Tapner; Elizabeth J Bernard; Richard Maher; Nick Pavlakis; Stephen J Clarke; Dale L Bailey

doi:10.1186/s13550-017-0292-1

Clinical and imaging-based prognostic factors in radioembolisation of liver metastases from colorectal cancer: a retrospective exploratory analysis

EJNMMI Res. 2017 Dec;7(1):46. doi: 10.1186/s13550-017-0292-1. Epub 2017 May 23.

Authors

Kathy P Willowson¹, Aimee R Hayes^{2

3}, David L H Chan^{2

3}, Michael Tapner⁴, Elizabeth J Bernard^{2

5}, Richard Maher⁶, Nick Pavlakis^{3

5}, Stephen J Clarke^{3

5}, Dale L Bailey^{2

7}

Affiliations

¹ Institute of Medical Physics, School of Physics, University of Sydney, Camperdown, NSW, Australia. kathy.willowson@sydney.edu.au.
² Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.
³ Department of Medical Oncology, Royal North Shore Hospital, St Leonards, NSW, Australia.
⁴ Research and Development, Sirtex Medical Limited, North Sydney, Australia.
⁵ Sydney Medical School, University of Sydney, Camperdown, NSW, Australia.
⁶ Department of Radiology, Royal North Shore Hospital, St Leonards, NSW, Australia.
⁷ Faculty of Health Sciences, University of Sydney, Camperdown, NSW, Australia.

Abstract

Background: The aim of this study was to investigate the relationship between absorbed dose and response of colorectal cancer liver metastases treated with [⁹⁰Y]-resin microspheres and to explore possible clinical and imaging derived prognostic factors.

Methods: FDG PET/CT was used to measure response of individual lesions to a measured absorbed dose, derived from post-treatment ⁹⁰Y PET imaging. Predicted dose was also derived from planning [^99mTc]-MAA SPECT data. Peak standardised uptake value and total lesion glycolysis (TLG) were explored as response measures, and compared to dose metrics including average dose (D _avg), biologically effective dose, minimum dose to 70% of lesion volume and volume receiving at least 50 Gy. Prognostic factors examined included baseline TLG, RAS mutation status, FDG heterogeneity and dose heterogeneity. In an exploratory analysis, response and clinico-pathological variables were evaluated and compared to overall survival.

Results: Sixty-three lesions were analysed from 22 patients. Poor agreement was seen between predicted and measured dose values. TLG was a superior measure of response, and all dose metrics were significant prognostic factors, with a D _avg of ~50 Gy derived as the critical threshold for a significant response (>50% reduction in TLG). No significant correlation was found between baseline TLG or RAS mutation status and response. Measured dose heterogeneity was a significant prognostic factor and when combined with D _avg had a positive predictive value for response >80%. In the exploratory analysis for prognostic factors of survival, low hepatic tumour burden and mean reduction in TLG >65% were independently associated with improved overall survival.

Conclusions: Lesions receiving an average dose greater than 50 Gy are likely to have a significant response. For lesions receiving less than 50 Gy, dose heterogeneity is a significant prognostic factor. Lesions receiving an average dose less than 20 Gy are unlikely to respond. A reduction in TLG may be associated with improved overall survival.

Keywords: 90Y; Dose; Heterogeneity; Radioembolisation; Response; SIRT.