Stage IIIC heterogeneity in FIGO 2018 cervical cancer staging: a retrospective single-center study on tumor size as an ındependent prognostic factor

To evaluate the impact of FIGO 2009 and 2018 staging on survival and assess the prognostic role of tumor size and lymph node status. Patients with cervical cancer treated between 2015 and 2025 at Mersin University were retrospectively re-staged. Of 212 patients, 68 were excluded, leaving 144 in the final cohort. After excluding Stage IA and Stage III–IV, a subgroup of 109 early-stage cases (FIGO 2009 stage IB and IIA/B) were analyzed. Survival was assessed with Kaplan–Meier and Log-rank tests; prognostic factors with Cox regression. The final study cohort (n = 144) had a mean age of 54.5±12.8 years and a mean tumor size of 42.5±21.7 mm. Squamous cell carcinoma accounted for 110 cases (76.4%). Of these, 109 early-stage patients (FIGO 2009 stage IB and IIA/B) formed the subgroup analyzed in Cox regression. Median survival for stage III was 26 months under FIGO 2009 versus 74 months under FIGO 2018. Tumor size was an independent prognostic factor (HR = 1.064, 95% CI 1.022–1.108, p = 0.003); each 1 mm increase corresponded to a 6.4% higher mortality risk. When outcomes stratified at the 4 cm cutoff, lymph node positivity was significant in univariate analysis but did not retain independent prognostic value in multivariate models. Stage IIIC patients with tumors ≤ 4 cm showed survival comparable to stage I–II; however, this subgroup was small (n = 11) with no recorded events, and findings should therefore be interpreted cautiously. Tumors > 4 cm predicted worse outcomes. This study demonstrates differences in survival outcomes between FIGO 2009 and FIGO 2018 stage III patients. Although limited by sample size, the findings suggest that cases reclassified as stage IIIC under the new system, but with tumor diameter ≤ 4 cm, may have more favorable prognoses. Given the retrospective design and limited sample size, our findings should be regarded as hypothesis-generating rather than practice-changing; requiring validation in larger, multicenter cohorts with standardized treatment protocols. These results contribute to the national dataset, provide comparability with international standards, and offer a foundation for future staging revisions and collaborative research.