Value of ¹⁸F-FDG PET/CT combined with CA125 and HE4 in the diagnosis of recurrent ovarian cancer and its peritoneal metastasis

Objective To explore the application value of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT combined with carbohydrate antigen 125 (CA125) and human epididymal protein 4 (HE4) levels in the diagnosis of recurrent ovarian cancer and prognostic evaluation of peritoneal metastasis.

Methods The imaging data of 89 postoperative ovarian cancer patients who underwent ¹⁸F-FDG PET/CT in the First Affiliated Hospital of Zhengzhou University from January 2016 to June 2021 were retrospectively analyzed. Pathological examinations diagnosed 59 patients with recurrent ovarian cancer (recurrence group, median age: 51(26–82) years), whereas 30 patients with ovarian cancer were diagnosed with benign peritoneal thickening by histopathological examination after surgery (non-recurrence group, median age: 55(34–79) years). All patients were followed up for at least 1 year. The efficacy of ¹⁸F-FDG PET/CT and contrast-enhanced CT in the diagnosis of recurrent ovarian cancer and postoperative stump recurrence, peritoneal metastasis, lymph node metastasis, and other metastases outside the abdominal cavity was calculated. The receiver operator characteristic curve of ¹⁸F-FDG PET/CT, CA125, HE4 alone, and combined detection of recurrent ovarian cancer was obtained, and the efficacy of independent or combined detection of recurrent ovarian cancer was analyzed. Comparison of diagnostic efficency used χ² text. The Cox model was used for multivariate prognostic analysis to evaluate the influence of multiple factors on the prognosis of patients with recurrent ovarian cancer and calculate the 95% confidence interval (CI). Kaplan–Meier survival curve was used to analyze the influence of a single prognostic factor on the overall survival of patients with recurrent ovarian cancer.

Results The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of ¹⁸F-FDG PET/CT in diagnosing recurrent ovarian cancer were 93.22%(55/59), 93.33%(28/30), 93.26%(83/89), 96.49%(55/57) and 87.50%(28/32), respectively, which were higher than those of contrast-enhanced CT (79.66%(47/59), 73.33%(22/30), 77.52%(69/89), 85.46%(47/55), and 64.71%(22/34)). The differences among all items were statistically significant (χ²=4.193–8.828, all P<0.05). In addition, the diagnostic efficacy of ¹⁸F-FDG PET/CT for postoperative stump recurrence, peritoneal metastasis, and lymph node metastasis (except the positive predictive values of peritoneal metastasis, sensitivity, and lymph node metastasis) were all higher than those of the contrast-enhanced CT (χ²=2.885–8.868, all P<0.05). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of ¹⁸F-FDG PET/CT combined with CA125 and HE4 in the diagnosis of recurrent ovarian cancer were 98.31%(58/59), 96.67%(29/30), 97.75%(87/89), 98.31%(58/59), and 96.67%(29/30), respectively, which were higher than the three methods were applied alone or two combined applications, except for the application of ¹⁸F-FDG PET/CT alone, the differences between the other items were statistically significant (χ²=5.192–27.101, all P<0.05). The diagnostic cut-off values of standardized uptake, serum CA125, and HE4 were 5.60, 91.80 U/mL, and 196.89 pmol/L, respectively. Peritoneal metastasis is an important independent prognostic factor for recurrent ovarian cancer (95%CI: 3.784–819.477, P=0.003). The overall survival of patients with negative peritoneal metastasis was significantly higher than that of patients with positive peritoneal metastasis (χ²=30.320, P<0.001). Peritoneal metastasis lesions were mostly distributed in the susceptible area of ​​peritoneal implantation and metastasis.

Conclusions ¹⁸F-FDG PET/CT performs better than contrast-enhanced CT in recurrence diagnosis and metastasis assessment of recurrent ovarian cancer. ¹⁸F-FDG PET/CT metabolic parameters, serum tumor markers, and the combined use of drugs can improve the diagnostic efficiency for recurrent ovarian cancer.