Abstract
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Objectives: To validate and assess the prognostic value of the revised 2018 International Federation of Gynecology and Obstetrics (FIGO) staging system for cervical cancer by PET/CT disease assessment.
Methods: IRB approved and HIPPA compliant retrospective study of 116 patients with biopsy proven squamous cell carcinoma of the cervix with a FDG PET/CT for initial staging. Clinical staging based on FIGO staging system 2009 at the time of diagnosis was recorded. FDG PET/CT studies were reviewed and reclassified based on the revised FIGO staging system 2018. PET/CT of patients with FIGO 2018 stage IIIC1 and IIIC2 were reviewed for the total number of abdominopelvic positive lymph nodes. Median follow up was 44.7 months. Cox proportional regression models were used to calculate the hazard ratio for FIGO 2009 and FIGO 2018 staging systems for both progression-free survival (PFS) and overall survival (OS). One sided permutation tests were used to test the model fit with FIGO 2009 versus FIGO 2018. Log likelihood was used as the fit criterion. Cox proportional hazard regression model was used to assess the correlation of the number of positive lymph nodes in patients with stage IIIC with OS and PFS.
Results: The patients’ mean age was 54.2 ± 13.1 years; based on the FIGO staging 2009, 21 patients had stage I, 56 had stage II, 24 had stage III and 15 had stage IV disease. Reclassification based on FIGO staging 2018 had 12 patients with stage I, 14 patients with stage II, 7 patients with stage III (A+B) and 68 with stage IIIC and 15 with stage IV. Eighty-eight patients had a change in stage using the FIGO 2018 staging system and were included in the analysis. 19 patients had disease related death and 28 patients had recurrence. Correlation of FIGO 2009 stage and PFS and OS was not significant, with hazard ratio (HR) of 1.06 (CI:0.85-1.32), p = 0.63 for PFS and HR of 1.12 (CI: 0.86-1.46), p = 0.40 for OS. Significant correlation was seen with FIGO 2018 stage and PFS and OS, with HR of 1.53 (CI:1.04-2.27), p = 0.03 and HR of 2.79 (CI: 1.43-5.46), p = 0.003), respectively. Permutation tests showed that FIGO 2018 staging system fit the data significantly better than FIGO 2009 staging system for both PFS (p = 0.041) and overall survival (p = 0.01). For patients with stage IIIC based on FIGO 2018 staging system, significant correlation was noted between the number of positive lymph nodes on PET/CT and worse OS was noted, with HR for incremental number of positive lymph nodes of 2.058 (CI: 1.133 - 3.739), p = 0.017.
Conclusions: FIGO staging system 2018 determined by PET/CT is significantly better than prior staging system 2009 to predict PFS and OS in patients with squamous cell carcinoma of the uterine cervix. Higher number of positive lymph nodes on PET/CT was significantly associated with worse overall survival.
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