YATES M(1)^, CABALAG CS(1)^, CORRALES BENITEZ M(1), YEH P(1,4), WONG SQ(1,4), CHONG L(2, 3), HII M(2, 3), DAWSON SJ(1,4,5), PHILLIPS WA(1), CLEMONS NJ(1), DUONG CP(1)
^Authors contributed equally to this work
1-Peter MacCallum Cancer Centre, Melbourne VIC
2-Department of Upper GI and Hepatobiliary surgery, St. Vincent’s Hospital, Melbourne VIC
3-Department of Surgery, St Vincent’s Hospital, University of Melbourne
4-Sir Peter MacCallum Department of Oncology, University of Melbourne
5-Centre for Cancer Research, University of Melbourne
Circulating tumour DNA (ctDNA) has clinical utility in monitoring treatment response and in the detection of disease recurrence in breast and colorectal cancer. The aim of this study was to explore the role of ctDNA in the management of patients with oesophageal cancer (OC).
Blood samples and tumour biopsies were collected from 52 patients after diagnosis of OC. In patients planned for surgery, blood samples were taken before and after neoadjuvant treatment, and during the surveillance period. Blood samples were analysed for the same mutations present on pre-treatment tumour biopsy using a custom targeted amplicon-based approach to cover mutational foci across 9 of the most commonly mutated genes in OC.
Somatic mutations in treatment-naïve OC tumour biopsies were detected in 45 out of 51 (88%) patients. Out of these 45 cases, 19 (42%) had detectable tumour-informed ctDNA in their plasma. The majority (79%) of patients who were ctDNA positive had either locally advanced or metastatic disease. In locally advanced nodal negative patients who were ctDNA positive, there was a trend towards inferior disease specific survival. After treatment, the emergence of new somatic mutations in serial surveillance blood samples was associated with recurrent disease (p = 0.038).
This study demonstrates that ctDNA may have clinically utility in the management of patients with OC by providing additional prognostic information. Assessment of ctDNA in post treatment blood samples may lead to the detection of early recurrent disease.