Long-term radiologic monitoring remains mandatory in non-functioning pituitary adenomas especially in the presence of an adenoma remnant

Abstract Resection with transsphenoidal surgery (TSS) is the mainstay of therapy for symptomatic non-functioning pituitary adenomas (NFPA). It is currently unclear whether radiologic follow-up could be discontinued in selected patients with favorable medium-term post-operative course. We performed a retrospective longitudinal unicentric study on patients who underwent TSS for NFPA at Lausanne University Hospital between 2000 and 2022. Based on MRI at 3 years (3Y) post-TSS, which served as the baseline timepoint for our study, eighty-five subjects were classified in three NFPA status categories : gross total resection (GTR, n = 41), stable residual adenoma (SRA, n = 20) or progressive residual adenoma (PRA, n = 24). Patients with PRA had harbored adenomas that were significantly larger before TSS ( p = 0.0007). A longitudinal analysis was then conducted solely in GTR and SRA patients to check for new-onset progression (recurrence or regrowth) at 5 years (5Y) post-TSS and at the last available follow-up (LAFU, 8.9 ± 2.9 years). Late progression was observed in 10.7% (6/56, two recurrences, four regrowths) at 5Y, with an additional 21.4% (9/42, one recurrence, eight regrowths) occurring between 5Y and LAFU. Resurgery or stereotactic radiosurgery were implemented in 9/15 (60%) of cases that progressed. The presence of residual adenoma at 3Y was significantly more frequent in progressive than in stable cases at LAFU ( p = 0.0002). However, the maximum diameter of the residual adenoma did not differ between the two groups. We were unable to detect an association between any other clinical, radiologic or histopathological marker and the risk of progression at any longitudinal timepoint. Although new-onset recurrences were relatively uncommon, regrowths of initially stable tumor remnants were common, overall highlighting the need to maintain long-term MRI monitoring in the majority of NFPA cases.