Endocrine Abstracts

Background: It is generally accepted that a post-operative cortisol of <50 nmol/l is a good predictor of long-term remission following trans-sphenoidal surgery (TSS).

Aim: We wished to determine the rate of late recurrence and need for consequent intervention in patients who had initial biochemical remission after TSS for pituitary dependent Cushing’s.

Methods: We performed a retrospective analysis of our patients who underwent TSS for pituitary Cushing’s between 2004 and 2019. Remission was defined as post-operative 0900 cortisol of <50 nmol/l within 3 months following TSS including patients who had surgical re-exploration during the initial admission due to a high day 2 post-operative cortisol. Those with post-operative basal cortisol greater than or equal to 50 nmol/l were considered to have ‘persistent disease’. Late recurrence was defined as the emergence of biochemical cortisol excess during the follow-up period (non-suppressible cortisol, and/or elevated urine free cortisol). Kaplan-Meier curves were plotted to determine the rates of recurrence and need for second intervention in patients initially in remission and re-intervention rates were compared to those with persistent disease.

Results: 86 patients (mean age 47years; 65 females, 21 males) underwent TSS for pituitary Cushing’s; 28/86 had macro- and 58/86 micro-adenomas. Median follow-up time was 9 years (range 1-16). 52/86 (60%) patients were in remission (39% of macro- and 71% of microadenoma) after TSS including 5/9 patients who had immediate re-exploration. 12/52 (23%) relapsed during follow-up. Using a Kaplan Meier analysis, the 5 year remission rate was 68% and 10 year remission rate was 53% in those with immediate post-op cortisol <50 nmol/l. In total, of the 52 patients in remission post-operatively, 23% relapsed and all had a further intervention (2^nd TSS n=6; radiotherapy n=6). Early relapse requiring intervention was uncommon in the remission group; only 1/52 patients had a second intervention within 1 year and 3/52 within 3 years. In contrast, 30/86 patients had persistent cortisol excess and of these 83% (25/30) had a repeat intervention in the first year after surgery.

Conclsions: Our data demonstrate a significant recurrence rate (32% at 5yrs) in patients considered by the most stringent criteria to be in remission following TSS leading to further intervention. Our data also demonstrate that those with persistent disease are likely to require a second intervention shortly after initial surgery. A post-operative cortisol of <50 nmol/l is a predictor of short-term remission but is not necessarily a confident long-term predictor of remission.