Medically treated prolactin-secreting pituitary adenomas: when should we operate?

The incidence of medical failure for prolactin (PRL)-secreting pituitary tumours is not well known. Object. The purpose of this study is to report clinical, radiographic and laboratory findings of PRL-secreting tumours that predict failed medical management.

An analysis of 92 consecutive patients was performed that met the inclusion criteria. Decision for surgery was made based on failure of dopamine agonists to either control clinical symptoms and normalise hormonal level or diminish mass effect on follow-up evaluation.

Of the 92 patients treated, 14 patients (15%) required trans-nasal, trans-sphenoidal pituitary surgery (TSS). One patient underwent surgery for repair of a skull defect and 13 patients (14%) required surgery after failed medical management. Higher initial PRL was statistically significant regarding the need for surgical intervention, but a persistently abnormal level after initiation of treatment was a more significant predictor (Fisher exact test, p = 0.005 vs. p < 0.001). Size was also a statistically significant factor (p = 0.014); macroadenomas had a relative risk of 9.27 (95% CI: 1.15-74.86) for needing surgery compared to microadenomas. In addition, macroadenomas with cavernous sinus (CS) extension and pre-operative visual field deficit demonstrated a strong tendency for surgical intervention.

Medical management remains the most effective treatment option for prolactinomas. A partial hormonal response to medical management seems to be the most significant predictive factor but adenomas > 20 mm, visual field deficit and invasion of the CS may help predict the need for surgery. We suggest a minimum trial period (at least 8 weeks) of medical treatment prior to the consideration of surgery.