EP1094 - ECE_3951 - Clinical course of non-functioning pituitary adenomas: insights from a retrospective single-center study

Abstract

Non-functioning pituitary adenomas (NFPAs) represent the most common subtype of pituitary macroadenomas and common finding among microadenomas. NFPAs show in a wide range of clinical behaviours, from clinically silent to compressive symptoms or hypopituitarism. Despite advances in surgery and radiotherapy techniques, optimal management of NFPAs remains debated, particularly finding reliable predictors of growth or recurrence. This study aimed to evaluate the clinical, radiological, and histopathological features of NFPAs and to analyze their long-term natural history in patients managed conservatively or treated surgically, with or without adjuvant therapies. Prognostic factors associated with tumor progression and clinical outcomes were also investigated. A retrospective single-centre study was conducted on 170 patients diagnosed with NFPA, all of whom underwent long-term clinical and radiological follow-up. Both patients under active surveillance and those who underwent transsphenoidal surgery, with or without adjuvant treatments, were included. Radiological progression occurred in 27.8% of patients in active surveillance. Probability of growth at 5 years was higher in macroadenomas (45.7%) compared with microadenomas (22.5%) (P = .030). Larger tumor volume was a significant predictor of progression (P = .004), like visual field defects (P = .008). Tumor progression was also linked to a higher incidence of new-onset hypopituitarism (P = .035). In the surgical cohort, the presence of any residual tumor significantly raised the risk of progression (P = .019), while visual improvement was linked to a reduction of more than 40% in tumor volume (P = .010). No significant correlation was found between proliferative markers (Ki-67, p53, mitotic count) and progression. Tumor shrinkage after reoperation was significantly lower compared with initial surgery (P = .017). Stereotactic radiosurgery achieved disease stability in 88% of treated patients, while temozolomide resulted in stabilization in two of three cases. Male patients presented with larger tumors and more frequent visual and endocrine impairment, but no sex-related differences in progression rates were observed. Active surveillance is a safe approach for asymptomatic patients, while surgery remains the treatment of choice in symptomatic tumors or those showing growth. Surgery provides prompt and effective visual improvement and local tumor control; however, postoperative hypopituitarism occurs in approximately one-third of cases. Complete surgical resection is the most reliable predictor of long-term tumor control, while proliferative markers appear to have limited prognostic value.