A key aim of neoadjuvant therapy in oes cancer is to increase the chance of complete R0 resection. Microscopic residual disease after surgery is reported in around 30% cases, mainly involving the circumferential resection margin (CRM), with current staging techniques unable to accurately identify pts at risk of residual tumour at the CRM. Previous small single site studies have shown that high res T2-weighted MRI achieves detailed imaging of oes anatomy and has the potential to serve as an additional non-invasive staging modality.
As part of the UK STO3 trial pts from participating centres with operable lower oes and type I/II OGJ adenoca were enrolled in the MRI observational sub-study. All pts underwent standard staging investigations, with additional MRI scans pre and post neoadjuvant chemo, followed by surgery. MRI parameters were consistent across sites and included CRM, T/N staging and apparent diffusion coefficient (ADC) assessment. Scans were reviewed locally and centrally to assess interobserver variability. Chemo response and association with pathological outcome were recorded.
Between Aug 2011 and Mar 2015 57 pts were recruited from 11 sites. Of these 32 had matched pre and post chemo scans and 28 had corresponding pathological outcome data available. Negative CRM status was correctly identified on post chemo MRI in 17/19 (89%) cases; positive CRM in 3/9 (33%) cases. When compared to pathological staging there was concordance between MRI T staging in 36% cases, with overstaging in 43% and understaging in 21%. Concordance between MRI and CT for T/N staging was 66% and 77% respectively. Tumour size reductions and ADC increases were observed during chemo. Local sites predicted significantly more CRM involvement than central review (48 vs 19%).
This represents the first prospective, multi-centre, national trial of MRI in oes cancer and is the first report of interobserver variability between treatment centres. Although limited by small numbers, MRI showed promising specificity to identify negative surgical margins and reasonable correlation with pathological outcome. Discrepancy between local and central review was observed, suggesting that more standardised methods of MRI assessment in oes cancer are required.
Clinical trial identification
Legal entity responsible for the study
Medical Research Council, UK.
Cancer Research UK, Clinical Trials Awards Advisory Committee.
D. Cunningham: Research funding: Amgen, AstraZeneca, Bayer, Celgene, Merck-Serono, Medimmune, Merrimack, Novartis, Roche, Sanofi. N. Starling: Research funding: AZ, BMS, Merck; Honoraria: AZ. All other authors have declared no conflicts of interest.