Reduced genomic tumor heterogeneity after neoadjuvant chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma
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Askar Obulkasim1, Bauke Ylstra2, Hendrik F. van Essen2, Christian Benner2, Sally Stenning3, Ruth Langley3, William Allum4, David Cunningham5, Imran Inam6, Lindsay C. Hewitt6,8, Nicolas P. West6, Gerrit A. Meijer2, Mark A. van de Wiel1,7,*, Heike I. Grabsch6,8,*
1Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, NL
2Department of Pathology, VU University Medical Center, Amsterdam, NL
3MRC Clinical Trials Unit at University College London, London, UK
4Department of Surgery, Royal Marsden NHS Foundation Trust, London, UK
5Department of Gastrointestinal Oncology, Royal Marsden NHS Foundation Trust, London and Surrey, UK
6Section of Pathology and Tumour Biology, Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK
7Department of Mathematics, VU University, Amsterdam, NL
8Department of Pathology and GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, NL
*Both senior authors contributed equally to this study (shared senior authorship)
Heike I. Grabsch, email: H.Grabsch@maastrichtuniversity.nl
Keywords: esophageal adenocarcinoma, array CGH, prognosis, chemotherapy
Received: March 06, 2016 Accepted: April 29, 2016 Published: June 06, 2016
Neoadjuvant chemo(radio)therapy followed by surgery is the standard of care for patients with locally advanced resectable esophageal adenocarcinoma (EAC). There is increasing evidence that drug resistance might be related to genomic heterogeneity. We investigated whether genomic tumor heterogeneity is different after cytotoxic chemotherapy and is associated with EAC patient survival. We used arrayCGH and a quantitative assessment of the whole genome DNA copy number aberration patterns (‘DNA copy number entropy’) to establish the level of genomic tumor heterogeneity in 80 EAC treated with neoadjuvant chemotherapy followed by surgery (CS group) or surgery alone (S group). The association between DNA copy number entropy, clinicopathological variables and survival was investigated.
DNA copy number entropy was reduced after chemotherapy, even if there was no morphological evidence of response to therapy (p<0.001). Low DNA copy number entropy was associated with improved survival in the CS group (p=0.011) but not in the S group (p=0.396).
Our results suggest that cytotoxic chemotherapy reduces DNA copy number entropy, which might be a more sensitive tumor response marker than changes in the morphological tumor phenotype. The use of DNA copy number entropy in clinical practice will require validation of our results in a prospective study.
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