Sam Mason, MBBS, BSc, MRCS, Liam Poynter, MBBS, BSc, MRCS, Efty Manoli, MSc, James Alexander, MBBS, MRCP, Petra Paizs, Bsc, Afeez Adebesin, RN, Robert Goldin, PhD, FRCPath, Ara Darzi, MD, FRCS, FACS, FRS, Zoltan Takats, PhD, James Kinross, PhD, FRCS. Imperial College London
Objectives: The unmet need in organ preservation strategies for rectal cancer is accurate, preoperative stratification of lesion risk, in addition to effectively deployed surgical options such as TAMIS. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) provides a platform for real time biochemical tissue analysis which, when coupled to existing endoscopic and surgical devices, provides unique biological insight. Here, we assessed the accuracy of REIMS in the diagnosis, risk stratification and therapeutic intervention in rectal cancer.
Methods: In this prospective pilot study, we recruited patients who underwent diagnostic colonoscopy or surgical resection for either rectal adenoma or cancer at two London hospitals. A modified, monopolar, electrosurgical handpiece was used to analyze tissues ex vivo, with the smoke plume aspirated directly into a Xevo G2-S ToF mass spectrometer (Waters Corporation). The relative abundance of cellular lipids was subjected to multivariate statistical modelling, including orthogonal partial–least-squares discriminant analysis. The primary outcome was the ability of REIMS to differentiate normal, adenomatous and cancerous rectal tissue. Secondary outcomes were the ability of REIMS to predict the presence of nodal disease, advanced tumor stage and histological features of poor prognosis.
Results: 37 patients with mean age of 70 were included in the study, yielding 225 spectra (108 normal, 82 tumour, 35 adenoma). Of the 26 patients who underwent surgical resection, 16 had nodal disease and 16 had T3/4 stage (as per TNM v7). REIMS differentiates normal, adenomatous and cancerous rectal tissues in real time with a diagnostic accuracy of 99.1%. For rectal cancers, REIMS had a sensitivity and specificity of 100% and 99.1% respectively for the presence of nodal disease, compared to 50% and 75% for pre-operative radiology. Furthermore, REIMS had a sensitivity of 93.3% and specificity of 98.8% in predicting tumors with advanced stage, compared to 69.2% and 42.9% respectively for preoperative radiology. Prognostic histological features could be predicted including extramural venous invasion (area under the curve (AUC) 1), tumor budding (AUC 0.99) and lymphovascular invasion (AUC 0.99). This technology has been translated into clinical practice where we have performed the first four in man studies of mass spectrometry augmented TAMIS, giving the surgeon real time biological feedback.
Conclusions: By sampling cellular lipids in real time, REIMS can accurately risk stratify rectal cancers based on underlying biology, potentially guiding clinical decision-making to promote organ preservation. There is also a role for improving the efficacy of rectal-sparing surgery, demonstrated in this initial cohort of augmented MS-TAMIS.
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 95243
Program Number: S129
Presentation Session: Colorectal III
Presentation Type: Podium