Predicting tumor progression in non-functioning pituitary macroadenomas following transnasal transsphenoidal resection: insights from a single-center retrospective cohort study

Introduction This retrospective, single-center study aimed to identify predictive factors for progression in postoperative residual findings of non-functioning pituitary macroadenomas (NFPMAs). The findings are intended to support individualized decisions regarding follow-up and adjuvant therapy. Methods A retrospective analysis was conducted on 212 patients treated at a tertiary referral center between 2007 and 2023. Patients underwent MRI-guided, transnasal transsphenoidal surgery for histologically confirmed NFPMAs. Pre- and postoperative tumor volumes were assessed alongside demographic, clinical, and histopathological data. Tumor configuration was classified using Hardy and Knosp scales. Subgroups were defined based on postoperative imaging: stable residuals, progressive residuals, or recurrence after gross total resection (GTR). Statistical analyses included multivariate testing and ROC analysis to determine predictive cutoff values. Results Of the 212 patients, initial radiological gross total resection (GTR) was achieved in 94/212 (44.3%); during follow-up, 62/212 (29.2%) had durable complete resection without recurrence, while 32/212 (15.1%) developed recurrence after initial GTR. Among patients with residual findings, 76 (64.4%) exhibited stable tumors after a mean of follow-up of 39 months, while 42 (35.6%) showed progression, which correlated significantly with larger preoperative tumor volumes (median: 11.6 cm 3 vs. 5.81 cm 3 , p < 0.001). ROC analysis identified 7.12 cm 3 as the optimal cutoff for distinguishing stable from progressive residual tumor volumes (AUC = 0.748). No significant differences between stable and progressive groups were observed in Hardy or Knosp classifications. Postoperative cortisol levels were nominally higher in patients with progressive residuals (14.10 μg/dL vs. 10.83 μg/dL; p = 0.022; exploratory). Conclusion According to our study, preoperative and postoperative tumor volumes represent pragmatic prognostic markers of progression in NFPMAs, with a critical cutoff of 7.12 cm 3 for stability. These findings could inform tailored follow-up strategies. Prospective studies are warranted to validate these results and further explore the impact of surgical and tumor characteristics on long-term outcomes.