Abstract CT113: A novel laser emission microscopy for early detection of colon cancer: Analysis of at-risk human colon from an interventional trial (research in progress)

Introduction: Accurate identification of neoplastic or pre-neoplastic lesions is traditionally dependent on microscopic identification of nuclear abnormalities. It is both time-consuming and challenging in early-stage lesions and difficult to detect. Laser-emission microscopy (LEM) that uses laser emission (not fluorescence) is an emerging technology that takes advantage of the finding that highly-proliferating cells like those in pre-neoplastic lesions can be distinguished from less proliferative cells by a lower laser emission dot density (LDD) when stained with a nuclear dye. We have successfully used this technique to detect (early) nuclear changes in a high-fat induced colon cancer model. LEM has also been used successfully to differentiate healthy tissue from cancerous tissue in human patients. Methods: This LEM system is capable of rapidly scanning tissue as large as 2 cm×2 cm in ~10 min. Both laser emission and regular fluorescence are imaged simultaneously, thus providing information regarding the lasing spot density and location within the human colon tissues. In this study, we employed colon biopsies from 12 human subjects (at risk for colorectal cancer). These subjects participated in a 90-day intervention, placebo-controlled, randomized trial. 8 subjects ingested known chemopreventives and 4 subjects took a placebo. Colon biopsies were taken from the sigmoid colon at baseline and after 90 days. The formalin-fixed, paraffin-embedded tissues were subjected to LEM microscopic assessment. For this, the tissues were sandwiched between two mirrors to form a laser cavity and laser excitation was applied. By comparing the laser emission spectra, highly proliferative tissue could be differentiated from less proliferative tissue. Post-treatment biopsies were compared to their baseline status. These biopsies were also stained with Ki67 to obtain their proliferation index to compare with the LEM results. Results: On average, there was a 20% increase in the LDD among the 8 subjects on chemopreventives while no change was seen in Ki67 positivity. In placebo group, Ki67 was decreased by 14% and LDD was 12% increased. On individual comparison, LDD and Ki67 data were correlated positively in 6 subjects. Conclusion: The preliminary data suggest that in histologically-normal but “at-risk” human colon LEM may pick early nuclear changes that may not be detected by a proliferation marker. Citation Format: Muhammad N. Aslam, Yun-Lu Sun, Ingrid Bergin, Mohamed Ali H. Jawad-Makki, Karsten Knuver, Danielle (Kim) Turgeon, James Varani, Xudong Fan. A novel laser emission microscopy for early detection of colon cancer: Analysis of at-risk human colon from an interventional trial (research in progress) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT113.