18F-DCFPyL PET/CT in advanced high-grade epithelial ovarian cancer: A prospective pilot study

Abstract

Objectives: Glutamate carboxypeptidase-II (GCP-II), a zinc metalloenzyme that resides in cell membrane, has been reported as overexpressed in the neovasculature of ovarian cancers. The study objective was to determine whether GCP-II targeted imaging with 18F-DCFPyL PET/CT can detect disease sites in women with advanced high-grade serous ovarian cancer (HGSOC).

Materials and methods: Twenty treatment-naïve women with advanced HGSOC were recruited (median age 60 years). Prior to commencing therapy (primary cytoreductive surgery [n=9] or neoadjuvant chemotherapy [n=11]), subjects underwent routine staging with contrast-enhanced abdominopelvic CT (=CT), followed by 18F-DCFPyL PET/CT (=PET). CT and PET were reported independently using a standardized reporting template assessing 25 sites. The performance of PET was compared to CT in all subjects and to surgery and surgical histopathology in 9 patients who underwent primary cytoreductive surgery.

Results: Of the 25 sites assessed in 20 patients, CT detected disease in 292/500 (58.4%) locations and PET detected disease in 171/500 (34.2%). Compared to CT the sensitivity (95% CI) of PET to detect disease in the upper abdomen, the gastrointestinal tract or the peritoneum was 0.29 (0.20,0.40), 0.21 (0.11,0.33) and 0.74 (0.64,0.82), respectively. In the surgical cohort, 220 sites in 9 patients were evaluated. The sensitivity and specificity of CT and PET were 0.85 versus 0.54 (p<0.001) and 0.73 versus 0.93 (p<0.001), respectively.

Conclusion: Although 18F-DCFPyL has higher specificity than CT in detecting advanced HGSOC tumor sites, it detects less disease sites than CT, especially in the upper abdomen and along the gastrointestinal tract, likely limiting its clinical utility.

Clinical trial registration: ClinicalTrials.gov, NCT03811899.

Keywords: 18F-DCFPyL; CT; PET/CT; PSMA; diagnostic performance; ovarian cancer.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2022 Metser, Kulanthaivelu, Chawla, Johnson, Avery, Hussey, Veit-Haibach, Bernardini and Hogen.

Figures

Figure 1

Patient flowchart.

Figure 2

Plot showing lesion detection by site for each of the 9 patients who underwent primary cytoreductive surgery. Blue background and pink background denote negative or positive station according to reference standard, respectively. A circle notes positive on CT and cross notes positive on PET.

Figure 3

68-year old with stage IIIC high-grade serous ovarian cancer. (A) Maximum Intensity Projection image of 18F-DCFPyL shows mild to moderate radiotracer uptake in omental metastases (solid arrows) and moderate radiotracer uptake in pelvic peritoneal metastases (dotted arrows). (B) Coronal contrast enhanced CT image shows peritoneal deposits in the posterior cul-de-sac (arrow). (C) Coronal PET/CT image (CT - left, fused PET/CT image – middle; PET – right) corresponding to B shows moderately radiotracer uptake in same metastatic deposit (concordant CT and PET). Metastatic disease was confirmed at surgery. (D) Coronal contrast enhanced CT image shows metastatic disease on right diaphragm (dotted arrow) and along capsular surface of liver (solid arrow). (E) Coronal PET/CT image (CT - left, fused PET/CT image – middle; PET – right) corresponding to D show no focal radiotracer uptake visible on right diaphragm or liver capsule. Surgical pathology confirmed CT findings of metastatic disease at these sites. (F) Coronal contrast enhanced CT image shows focal thickening along right lateral wall of ascending colon (short arrows), suspected to represented serosal metastasis. (G) Coronal PET/CT image (CT - left, fused PET/CT image – middle; PET – right) corresponding to F shows no focal radiotracer uptake on the serosal surface of the ascending colon. No serosal disease on surface of the right colon was found at surgery.