Presentation Authors: Christopher Corbett*, Lydia Frenzel-Sulyok, Michael Shin, Philadelphia, PA, Philip Low, West Lafayette, IN, Sunil Singhal, Thomas Guzzo, Philadelphia, PA
Introduction: Patients with renal cell carcinoma (RCC) commonly develop metastatic disease, and 5-year survival in patients with untreated metastases is poor. The lungs are the second most common site of RCC metastases, and pulmonary metastasectomy can more than double 5-year survival in these patients. Intraoperative molecular imaging (IMI) has been used to identify thoracic metastases for a variety of primary tumors, including colorectal cancer and osteosarcomas. Here we describe our findings from clinical trials utilizing three different fluorescent dyes and their ability to identify thoracic RCC metastases: EC17, which fluoresces in the visible spectrum, and ICG and OTL38, which both fluoresce in the near-infrared region (NIR).
Methods: All studies were approved by our institution&[prime]s Institutional Review Board and all patients gave informed consent. Patients received one of three dyes: EC17, ICG, or OTL38. Depending on the dye infused, patients were infused between 4 and 24 hours prior to surgery at doses ranging from 0.025 to 5 mg/kg. All tumors were imaged either in vivo and/or ex vivo. Fluorescence signal intensities of tumor and surrounding tissues were compared to compute tumor to background ratios (TBR), which were quantified using ImageJ. TBRs greater than 2 were considered positive for fluorescence.
Results: Five patients had pathology proven thoracic RCC metastases, 4 pulmonary and 2 lymphatic (Table 1). Metastases ranged in size from 1.1 to 3.9 cm. Two patients received EC17, two received ICG, and one received OTL38. Patients who received EC17 did not exhibit tumor fluorescence ex vivo. In patients receiving ICG and OTL38, pulmonary metastases had TBRs of 2.85 with ICG and 2.35 with OTL38. Lymphatic metastases had TBRs of 9.8 with ICG and 4.3 with OTL38.
Conclusions: Patients infused with dyes fluorescing in the NIR exhibited strong fluorescent signals in pulmonary and lymphatic thoracic metastases. The strongest fluorescent signals were present in lymphatic metastases, though this was not related to distance from the pleural surface. This preliminary data suggests IMI can serve as an effective adjunct to the surgeon in identifying thoracic RCC metastases. Future studies to assess the role of IMI in identifying RCC metastases in other locations are warranted.
Source of Funding: Research reported in this publication was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under award number TL1TR001880. The content is solely the responsibility of the authors and does not neces