Recently, a research team led by Professor Song Shaoli (Director of the Department of Nuclear Medicine, Shanghai Cancer Center, Fudan University) and Professor Wu Xiaohua (Director of the Department of Gynecology, Shanghai Cancer Center, Fudan University), conducted a multi-year study on the clinical application of molecular imaging probe in platinum-sensitive recurrent ovarian cancer patients, and the achievement has been confirmed firstly in the world: 68Ga-FAPI PET/CT imaging can accurately radiological evaluate and select platinum-sensitive recurrent ovarian cancer patient who benefit from secondary reduction. The new exciting study has been published online in European Journal of Nuclear Medicine and Molecular Imaging (EJNMMI, Q1，IF=10.057).
Nuclear Medicine Department Solve Clinical Problem
Ovarian cancer is one of the most common and lethal gynecologic cancers worldwide. Most patients experience disease relapse or progression from platinum-sensitivity to platinum-resistance. Therefore, the treatment and management of platinum-sensitive recurrent patient is particularly important. Professor Wu Xiaohua said that platinum-sensitive recurrent patient will benefit to longer survival only if secondary reduction achieved complete reduction (R0). It is urgent for gynecological doctor how to accurately select these patients who can benefit from secondary surgery.
Even though 18F-FDG PET/CT could diagnose ovarian cancer lesion with high sensitivity and specificity, professor Song Shaoli said, the diagnosis was limited in intestinal cavity, diaphragm/liver capsule and small size of peritoneal carcinomatosis due to physiological uptake, which are all pivotal for tumor respectability and curability. Therefore, more sensitive and accurate imaging technique is urgently required for precise evaluation and individualized management of platinum-sensitive recurrent ovarian cancer.
Professor Song Shaoli said fibroblast-activation protein (FAP) is overexpressed in cancer-associated fibroblasts, which are the predominant component in the stroma of epithelial neoplasms. Fibroblast-activation protein inhibitor (FAPI) can specifically target and bind to FAP. 68Ga-FAPI probe makes FAP visualization come true, which demonstrated promising results in various cancer. 68Ga-FAPI is excreted by urine without physical uptake in liver and intestine, and has a unique advantage in the diagnosis of abdominopelvic implant lesion, especially for peritoneal metastasis.
Blockbuster Research Finding Booster Precision Treatment of Ovarian Cancer
In the study, 29 platinum sensitive recurrent ovarian cancers were enrolled randomly. 18F-FDG and 68Ga-FAPI PET/CT were obtained within one week for radiological evaluation. The results showed up to 75.86% of patients displayed inconsistency between two scans. 68Ga-FAPI was superior to 18F-FDG PET/CT for the detection of recurrent lesions, and the sensitivity, accuracy were 96.30% vs 49.07%, 97.40% vs 63.87%, respectively. Especially for peritoneal lesion, 68Ga-FAPI PET/CT had unique advantage, and the minimum diameter of measurable lesion was 2mm. According visual scoring system, 68Ga-FAPI PET showed a much higher visual score than 18F-FDG PET (41 vs 4) for lesion.
The treatment strategies were changed in 17.24% of patients after 68Ga-FAPI PET/CT imaging. 18F-FDG imaging suggested secondary reduction in 3 patients, but more and more extensive lesions were detected in subsequent 68Ga-FAPI PET/CT, which could not be resect completely. Thus, the treatment was changed to chemotherapy, avoiding unnecessary surgical trauma. Metastasis lesions were diagnosed in 2 patients earlier by 68Ga-FAPI scan, and the best treatments were given in time. Respectable lesion was found on 68Ga-FAPI PET/CT in 1 patient with negative 18F-FDG imaging, and the treatment was changed from follow-up to R0 surgery. However, 1 patient was negative on 18F-FDG imaging, but multiple peritoneal metastases were found by 68Ga-FAPI imaging, so the treatment was changed from follow-up to chemotherapy, avoiding the rapid progression of tumor.
In the study, finally 15 patients experienced surgery, and up to 14 patients achieved complete resection. These results suggested that 68Ga-FAPI PET/CT could impact on treatment strategy and recognize proper surgical candidates. And the evaluation of abdominopelvic tumor burden by 68Ga-FAPI imaging is more consistent with the real intraoperative lesion distribution. Professor Song further explained, 68Ga-FAPI PET also presented larger tumor burden than 18F-FDG according to the Eisenkop score (16 vs 27, p=0.025).
Talking about the clinical application value of 68Ga-FAPI imaging in ovarian cancer, Professor Song said excitedly, preliminary results have shown the advantages of 68Ga-FAPI imaging in the diagnosis of recurrent ovarian cancer, and given us great confidence and encouragement. Our team will further expand the sample size, promote the research result, booster clinical diagnosis and treatment to benefit more patients. Currently, patients can apply 68Ga-FAPI examination through the comprehensive evaluation of Professor Wu Xiaohua's multidisciplinary clinic.