Topic: Cases in Clinical MS
Podium Presentation in Room 4 on Wednesday at 9:40 (Chair: Peggi Angel / Anna Krieger)
Authors: Natasja N.Y. Janssen (1), Martin Kaufmann (2), Ami Wang (3), Kaitlin Vanderbeck (3), Kevin Yi Mi Ren (3), Alice Santilli (1), Parvin Mousavi (1), John F. Rudan (4), Gabor Fichtinger (1), Doug McKay (4)
Basal cell carcinoma (BCC) is the most commonly diagnosed cancer, involving 2.75 million cases worldwide. Typical management of BCC entails surgical resection of the cancer, followed by gold-standard histopathologic analysis of the resected specimen. However, results are only available after surgery. Due to the increasing number of BCC patients worldwide, incomplete surgery leads to many revision surgeries and subsequent healthcare costs, impaired cosmetic outcome and patient distress. Ideally, the surgeon would have information about the tissue type during the operation.
Background: Rapid Evaporative Ionization Mass Spectrometry (REIMS) has recently emerged as a real-time tissue identification technique, based on analysis of cancer-specific molecular profiles within surgical smoke produced during electrosurgical tissue dissection. We hypothesized that BCC, fat and benign skin tissue have distinct molecular profiles, based on altered ratios of lipids and fatty acids, as noted in other malignancies. This study evaluated the accuracy of REIMS for characterization of BCC, fat and benign skin tissue on fresh, ex-vivo resection specimens from BCC patients. Furthermore, the clinical feasibility of intraoperative use of REIMS was evaluated.
MS Methods and Results: A multidisciplinary team has established clinical workflows for both ex vivo and intraoperative analysis of BCC resection specimen in Kingston Health Science Centre (KHSC). A total of 54 excision specimens were obtained from 47 patients. The specimens were directly transferred to a mobile REIMS mass spectrometer within an operating room (OR). A dermapathologist examined the specimen to localize areas of BCC, fat and benign skin tissue, and were subsequently burnt to acquire REIMS spectra of all tissue types. The burnt tissue areas were validated by pathology. Principal component analysis (PCA) and linear discriminant analysis (LDA) of the m/z 600-900 regions of REIMS spectra on BCC (n=113), fat (n=51) and benign skin (n=99) showed good clustering among the 3 tissue types, and had a correct classification rate of 88%, based on cross-validation. Intraoperative REIMS was successfully integrated in the OR without interfering with the standard clinical workflow. Five patients underwent skin cancer surgery in the OR while intraoperative REIMS spectra were acquired. The average resection time, including REIMS spectra acquisition, was 5.8 ± 1.1 min.
Discussion and Conclusion: This study shows the potential clinical feasibility of ex vivo and intraoperative REIMS during skin cancer surgery. Future studies will focus on improving diagnostic accuracy of the BCC recognition model, as well as evaluation of the safety and feasibility of REIMS as an intraoperative decision support system. BCC is an ideal model for assessing the clinical utility of REIMS because it is a common, low-risk cancer and surgery is rapid, enabling access to a large number of specimens within a short time.
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