Conservatively managed non-functioning pituitary macroadenomas – cohort study from the UK Non-functioning Pituitary Adenoma Consortium

Objective

Surveillance is often adopted for asymptomatic non-functioning pituitary macroadenomas (macroNFPAs). Due to low-quality evidence, uncertainty remains on optimal frequency of imaging/biochemical monitoring and indications for surgery. We assessed the natural history and outcomes of patients with macroNFPA who had monitoring as initial management choice from the UK NFPA Consortium.

Design

This was a multicentre, retrospective, cohort study involving 21 UK endocrine departments.

Methods

Clinical, imaging, and hormonal data of 949 patients followed up between January, 1, 2005 and March, 1, 2022 were analysed.

Results

Incidence rate for tumour enlargement was 9.8 per 100 patient-years (95% CI, 8.8-10.8), with cumulative probabilities 1.6%, 8.1%, 18.4%, 29.2%, and 43.6% at 6-month, 1-year, 2-year, 3-year, and 5-year follow-up, respectively; rates were higher in tumours abutting/displacing optic chiasm than those not in contact with it. Amongst macroNFPAs not in contact with optic chiasm showing enlargement within 6 months, none impacted visual fields. In tumours with enlargement and continued monitoring (median 2.6 years), further growth occurred in 60.5% (33.8% probability at 2 years), stability in 35.5%, and shrinkage in 4.0%. Rates of new pituitary hormone deficits were 4.0%-4.9%, mainly driven by tumour enlargement. After transsphenoidal surgery, rates of hypopituitarism reversal were 12%-17% and those of additional anterior pituitary hormone deficits were 12%-15% (permanent vasopressin deficiency 3.5%).

Conclusions

Our data provide evidence for monitoring protocols. MacroNFPAs not in contact with optic chiasm require less frequent imaging, and first follow-up scan can be delayed to 1 year. After first enlargement, variable tumour behaviour can occur. New hypopituitarism in stable tumours is rare, challenging necessity of regular pituitary function assessment.