Cancer diagnosis with Photo dynamic Raman spectroscopy

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Photodynamic diagnosis (PDD) with Raman spectroscopy is expecting to be a novel modality for cancer diagnosis. Since 2003, we developed Raman Diagnostic System (RDS) for gastrointestinal malignancy. The goal of RDS is real-time optical diagnosis during endoscopy or surgery. Endoscopic RDS enables to be a real-time implementation to assess the mucosal pathology in gastrointestinal tract. Intraoperative RDS has the possibility of real-time diagnosis for lymph node metastasis or peritoneal dissemination, resulting that the patients with gastrointestinal cancer can receive less-invasive and most suitable surgery. Our RDS has a novel detector with high sensitivity in which the influence of autofluorescence on Raman signal intensity could be reduced in a limited range at 1064 nm excitation. Previously, we reported the preliminary study of RDS, in which Raman spectra were assessed with principle component analysis (PCA). The sufficient accuracy was obtained. Next we improved RDS to increase the clinical usefulness. We examined gastric cancer specimens removed by endoscopic biopsy. The results had better reproducibility and reliability without PCA. In the cancer diagnosis, the sensitivity was 72 %, specificity was 70 % and accuracy was 71 %. And we have confirmed stability of measurements and the level of accuracy. We are improving RDS to elevate the accuracy.We are going to exam the gastric cancer specimens removed by operation. We can measure the spectrum of cancer lesion to normal tissue continuously.RDS is a novel diagnostic implementation for the gastrointestinal cancer. The present data strongly suggest that improvement of both instruments and methods of RDS increases the accuracy of cancer diagnosis and the application of RDS to endoscopy or surgery is expected to achieve real-time cancer detection without histological examination.