Introduction/Background Protoporphyrin IX, a metabolic product of 5-aminolevulinic acid (5-ALA), becomes photoactive and emits red fluorescence when excited by visible blue light. Photodynamic diagnosis (PDD) using 5-ALA has proven effective in fluorescence-guided surgery for malignant glioma and bladder cancer. This study aims to investigate the diagnostic accuracy of intra-peritoneal dissemination in advanced ovarian cancer using PDD with 5-ALA.

Methodology In this prospective single-center study, patients with advanced ovarian cancer were administered oral 5-ALA (20 mg/kg) four hours before staging laparoscopy. Fluorescence excitation utilized a blue light source (D-LIGHT System; Karl Storz Endoscopy, Germany). Tumor and non-tumor locations were documented under white light (WL) and fluorescent light (FL). Biopsies were obtained from suspected tumor sites under WL and/or FL, with additional samplings from areas appearing normal under both lights. Pathological examination assessed malignancy, and the association between imaging data and pathology was explored.

Results Seven patients (comprising 5 high-grade serous carcinomas, 1 clear cell carcinoma, and 1 pseudomyxoma of the peritoneum) participated between January and March 2019. Seventy-one biopsies from the peritoneum, omentum, and fallopian tube serosa were acquired. The median number of biopsies per patient was 10 (range: 6 to 14). Sensitivity, specificity, and positive and negative predictive values for detecting tumors under WL were 88%, 59%, 83%, and 68%, respectively. Under FL, these values were 96%, 90%, 96%, and 90%, respectively. No severe adverse events related to oral administration of 5-ALA were observed.

Conclusion The superior accuracy of PDD with 5-ALA over standard WL in identifying peritoneal dissemination in advanced ovarian cancers emphasizes its potential as a valuable diagnostic tool for ovarian cancer staging. This heightened precision may contribute to optimizing the outcomes of cytoreductive surgery.

Disclosures Akira Yabuno recives honoraria from AstraZeneca, Eisai, Takeda and MSD. The other authors made no disclosures.