Discontinuation of Drug Treatment in Cushing's Disease Not Cured by Pituitary Surgery

Objective: When transsphenoidal surgery (TSS) does not cure Cushing's disease (CD), 4 treatments are available: drug treatment (DT), second TSS (2nd TSS), bilateral adrenalectomy (BA), and pituitary radiotherapy (PR). DT is attractive but supposes long-term continuation, which we aimed to evaluate. Design and Methods: Retrospective study, in a center prioritizing 2nd TSS, of 36 patients, including 19 with TSS failure and 17 with recurrence, out of 119 patients with CD treated by a first TSS, average follow-up 6.1 years (95% confidence interval 5.27-6.91). Control was defined as normalization of urinary free cortisol (UFC) and final treatment (FT) as the treatment allowing control at last follow-up. We also analyzed discontinuation rates of DT in published CD prospective clinical trials. Results: Control was achieved in 33/36 patients (92%). DT was initiated in 29/36 patients (81%), allowing at least 1 normal UFC in 23/29 patients (79%) but was discontinued before last follow-up in 18/29 patients (62%). DT was FT in 11/29 patients (38%), all treated with cortisol synthesis inhibitors. Second TSS was FT in 8/16 (50%), BA in 14/14 (100%), and PR in 0/5. In published trials, discontinuation of DT was 11% to 51% at 1 year and 32% to 74% before 5 years. Conclusion: DT allowed at least 1 normal UFC in 23/29 patients (79%) but obtained long-term control in only 11/29 (38%), as discontinuation rate was high, although similar to published data. Interestingly, a successful 2nd TSS was the cause for discontinuing efficient and well-tolerated DT in 5 patients. Further studies will show whether different strategies with cortisol synthesis inhibitors may allow for a lower discontinuation rate in patients not candidates for a 2nd TSS so that BA may be avoided in these patients.