Endocrine Abstracts

Introduction: The 2017 WHO Classification of Pituitary Tumors grades silent corticotroph adenomas (SCAs) as high-risk adenomas due to their aggressive clinical behaviour (high probability of recurrence). Nonetheless, studies comparing recurrence rates of SCA with other non-functioning pituitary adenomas (NFPAs) subtypes have provided conflicting results necessitating review of the evidence this recommendation relies on.

Aims: To estimate recurrence rates of SCAs following primary treatment (surgery ± radiotherapy) and recurrence rate ratios (RRR) between SCAs and other NFPA subtypes by performing a systematic review and meta-analysis of relevant published studies.

Methods: Extensive literature search of Medline, Embase and Cochrane Library up to October 31, 2017 was conducted. Recurrence rates, effect size (ES), RRRs and 95% confidence intervals (CIs) were estimated from each study and pooled using random effects meta-analysis model.

Results: For determination of SCAs recurrence rates, 15 observational studies of low risk of bias including 310 patients were finally selected. Overall, recurrence rate of SCAs was 5.69 (95% CI, 4.1–7.49) per 100 person-years. In studies with mean follow-up <5 or ≥5 years, 25% (ES 0.25;95% CI, 0.13–0.38) and 31% (ES 0.31; 95% CI, 0.23–0.39) of the patients had recurrence, respectively. Recurrence rate after surgery alone was 5.41 (95% CI, 4.1–7.49) cases per 100 person-years and after surgery + radiotherapy 4.88 (95% CI, 0.67–11.54) cases per 100 person-years. For RRR determination, 10 observational studies of moderate risk of bias including 244 SCA and 1622 NFPA patients were selected. RRR between these two groups was not significant (1.44; 95% CI, 0.9–2.33, P=0.13). Focus on tumours treated solely by surgery also revealed no significant RRR (1.17; 95% CI, 0.79–1.75, P=0.429).

Conclusions: RRR estimation which takes into account length of follow-up has not confirmed higher probability of SCA recurrence compared with other NFPA subtypes necessitating further methodologically robust studies to support the 2017 WHO recommendation.