Introduction Real-time identification of metastatic ovarian cancer in vivo during tumor-reductive surgery (TRS) is challenging, especially for patients who have undergone neoadjuvant chemotherapy (NACT). In this study, we investigated the feasibility of using the hand-held MasSpec Pen (MSP) technology for intraoperative molecular analysis and tissue identification of metastatic sites during ovarian cancer TRS. The MSP is an innovative hand-held probe coupled to a mass spectrometer that non-destructively analyzes the metabolic composition of tissues in <20 seconds.

Methods Patients with advanced high-grade serous carcinoma (HGSC) who received NACT and scheduled for interval TRS were consented prior to surgery. An orbitrap mass spectrometer equipped with a MSP source was placed ~5 m away from the operating table. In vivo MSP measurements were performed by gynecologic oncologists and ex vivo measurements were made by research personnel. Analysis sites were marked with surgical ink for pathological analysis. The data was used to build statistical classifiers.

Results Twenty-seven patients with advanced HGSC underwent interval TRS with MSP analysis. We obtained rich metabolic data of tissues including ovary(n=27), fallopian tube(n=4) peritoneum(n=51), and omentum (n=16). The profiles were characterized by high relative abundance of small metabolites and glycerophospholipids, and consistent with prior data from ex vivo tissues. Direct correlation of intraoperative molecular analysis was made with final pathology. Accurate prediction of HGSC was achieved from several in vivo data samples.

Conclusion/Implications Intraoperative data collection utilizing the hand-held MSP is feasible and can be used in combination with statistical analysis for real-time diagnosis during TRS to distinguish ovarian cancer from normal tissues.