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Reduced genomic tumor heterogeneity after neoadjuvant chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma.

ABSTRACT: 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.

SUBMITTER: Obulkasim A

PROVIDER: S-EPMC5190081 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Reduced genomic tumor heterogeneity after neoadjuvant chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma.

Obulkasim Askar A Ylstra Bauke B van Essen Hendrik F HF Benner Christian C Stenning Sally S Langley Ruth R Allum William W Cunningham David D Inam Imran I Hewitt Lindsay C LC West Nicolas P NP Meijer Gerrit A GA van de Wiel Mark A MA Grabsch Heike I HI

Oncotarget 20160701 28

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 ...[more]

PMID: 27286451

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Project description:The incidence of oesophageal adenocarcinoma (OeC) has been increasing rapidly in most Western countries during the last few decades. Although multimodal treatment combining pre-operative chemotherapy with radical surgical resection has become the standard of care in the UK for all patients with locally advanced resectable disease, the 5-year survival rate in this patient group is less than 25%. Only 30% of all patients will benefit from pre-operative chemotherapy. Hence, there is an urgent clinical need to identify genomic markers that allow stratification of patients for a more individualised therapy approach. The goal of this study is to use whole genome high-resolution array CGH to examine the DNA copy number profile of a subset of OeC patients recruited into the OE02 trial and establish it’s relationship with clinicopathological variables including pathological tumor regression and patient survival. High-resolution array CGH analysis was conducted on 84 formalin fixed paraffin embedded resection samples obtained from subjects enrolled in the Oe02 trial. We compared the DNA copy number profiles between patients treated with chemotherapy and surgery and those treated with surgery alone. DNA copy number entropy was assessed to identify differences in overall copy number aberrations between the two treatment groups. Furthermore, the association between DNA copy number aberrations and tumor regression grade was investigated. The genetic make-up of OeCs investigated in the current study proved to be highly complex reducing our ability to determine the background normal copy number level in a tumor sample. Using DNA copy number entropy as a measure to compare sample profiles, we identified significant treatment arm specific DNA copy number aberration patterns predominantly in chromosome 1 and 5. High DNA copy number entropy was associated with longer overall survival. Differential DNA copy number entropy was observed between the two treatment groups, and the positions of the driving DNA regions were identified. To our surprise, the differences between the treatment groups went unnoticed when a standard test was applied. We also found that the DNA copy number entropy was strongly correlated with patients’ overall survival and clinicopathological characteristics. To the best of our knowledge, this is the first study in OeC quantitatively showed that the tumor heterogeneity was reduced by chemotherapy. And, the observed tumor heterogeneity was shown to has prognostic value. However, further research is needed to narrow down these regions to a few driving genes/probes that may aid in predicting whether a new patient will benefit from chemotherapy.

Dataset Information

Reduced genomic tumor heterogeneity after neoadjuvant chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma.

Publications

Reduced genomic tumor heterogeneity after neoadjuvant chemotherapy is related to favorable outcome in patients with esophageal adenocarcinoma.

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