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Background: Neoadjuvant chemoradiotherapy (CRT) is used in locally advanced rectal cancer when tumours threaten the circumferential resection margin, with varying response to treatment. This experimental study aimed to identify significantly differentially expressed proteins between patients responding and not responding to CRT, and to validate any proteins of interest., Methods: Mass spectrometry (with isobaric tagging for relative quantification) analysis of rectal cancers pre- and post-CRT, and at resection. Validation of proteins of interest was performed by assessing tissue microarray (TMA) immunohistochemistry expression in a further 111 patients with rectal cancer., Results: Proteomic data are available via ProteomeXchange with identifier PXD008436. Reduced abundance of contributing peptide ions for acid ceramidase (AC) (log fold change -1.526, p = 1.17E-02) was observed in CRT responders. Differential expression of AC was confirmed upon analysis of the TMAs. Cancer site expression of AC in stromal cells from post-CRT resection specimens was observed to be relatively low in pathological complete response (p = 0.003), and relatively high with no response to CRT (p = 0.017)., Conclusion: AC may be implicated in the response of rectal cancer to CRT. We propose its further assessment as a novel potential biomarker and therapeutic target., Significance: There is a need for biomarkers to guide the use of chemoradiotherapy in rectal cancer, as none are in routine clinical use. We have determined acid ceramidase may have a role in radiation response, based on novel proteomic profiling and validation in a wider dataset using tissue microarrays. The ability to predict or improve response would positively select those patients who will derive benefit, prevent delays in the local and systemic management of disease in non-responders, and reduce morbidity associated with chemoradiotherapy., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Next generation sequencing technology has facilitated mapping of the colorectal cancer genotype and furthered our understanding of metastogenesis. The aim of this study was to investigate for conserved and different mutations in the exomes of synchronously resected primary colorectal tumour and liver metastases. This information could potentially be utilised to guide the treatment of advanced disease with the help of biological information from the primary tumour., Methods: We performed exome sequencing of synchronously resected primary colorectal cancer and colorectal liver metastases as well as normal colonic mucosa and liver parenchyma, from four patients who had received neo-adjuvant chemotherapy, at a depth of 50X using the Ion Proton platform. Raw data was mapped to the reference genome prior to variant calling, annotation and downstream analysis., Results: Exome sequencing identified 585 non-synonymous missense single nucleotide variants (SNVs), of which 215 (36.8%) were unique to the primary tumour, 226 (38.6%) unique to the metastasis and 81 (13.8%) present in patient matched pairs. SNVs identified in the ErbB pathway appear to be concordant between primary and metastatic tumours., Conclusion: Only 13.8% of the metastatic exome can be predicted by the genotype of the primary tumour. We have demonstrated concordance of a number of SNVs in the ErbB pathway, which may inform selection of therapeutic agents in advanced colorectal cancer., (Copyright © 2017 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.)