The issue of false positive lymph nodes on [¹⁸F] FDG-PET/CT for cervical carcinoma and consequences for treatment

Objective: Since 2018 imaging and histopathology are incorporated in the International Federation of Gynecology and Obstetrics (FIGO) staging system of cervical cancer. The aim of this study was to assess the positive predictive value (PPV) and negative predictive value (NPV) of 2-[¹⁸F] fluoro-2-deoxy-D-glucose [¹⁸F] FDG-PET/CT ([¹⁸F] FDG-PET/CT) for lymph node involvement in patients with cervical cancer and to review the literature. Methods: First, PPV and NPV were calculated in a retrospective study including 98 patients with stage ≥IB1 cervical cancer that underwent a [¹⁸F] FDG-PET/CT before surgery. Second, the literature was reviewed on PPV and NPV of PET/CT in cervical cancer. Twenty-one studies were included and analyzed using the Spearman's rank correlation coefficient. Results: In the retrospective study 63 patients (64%) were treated with a radical hysterectomy and complete pelvic lymph node dissection, and 35 patients (36%) underwent a lymph node debulking followed by chemoradiation. The PPV was 79% (inconclusive PET/CT interpreted as suspicious) or 89% (inconclusive PET/CT interpreted as non-suspicious) and the NPV was 81% or 80% respectively. The PPV in the subgroup of 63 patients treated with pelvic node dissection was 56% or 70% respectively. The NPV was 81% for both strategies. Literature results showed a positive correlation (R = 0.354) between the percentage of patients with positive nodes and the PPV of PET/CT. Conclusion: [¹⁸F] FDG-PET/CT overestimates the incidence of lymph node metastases, especially in early stage cervical cancer. This may cause a shift of the treatment regime from surgery to radiotherapy. Therefore, histopathological confirmation of [¹⁸F] FDG-PET/CT-positive nodes is essential to guide therapy decisions.