Postoperative treatment of clinically nonfunctioning pituitary adenomas with dopamine agonists decreases tumour remnant growth.

Objective: There is no consensus as to the optimal postoperative treatment of patients with clinically nonfunctioning pituitary adenomas (NFPA) in whom total tumour removal has not been achieved. In this study we assessed whether dopamine agonist (DA) treatment can prevent postoperative remnant enlargement in NFPA.
Design and Methods: Thirty-three patients (25 men/8 women; mean age, 61.7 +/- 11.2 years; mean follow-up, 40.6 +/- 4.8 months) were treated with DA, and their outcome was compared to that of 47 untreated patients (33 men/14 women; mean age, 59 +/- 2 years; mean follow-up, 42.9 +/- 4.2 months).
Results: Tumour mass decreased or remained stable in 18/20 patients in whom DA treatment was initiated upon detection of residual tumour on postoperative MRI (group I). In 13 subjects (group II), DA therapy was started when tumour remnant growth became evident during the course of routine follow-up. Tumour growth stabilized or decreased in 8/13 (61.5%) of these patients. In contrast, tumour size remained stable in only 38.3% (18/47) of the untreated subjects (P < 0.0001 for comparisons among the three groups) and increased in the remaining 29 patients. Tumour enlargement free mean survival time was 103.7 +/- 8.8 months (CI 86.3-121) for group I, 43.9 +/- 9.6 months (CI 25.2-62.8) for group II and 36.7 +/- 3.8 (CI 29.2-44.2) for the control group (P = 0.0017). Treatment vs. control hazard ratio for tumour enlargement was 0.135 for group I (P = 0.007, 95% CI 0.032-0.577) and 0.892 for group II (P = 0.817; 95% CI 0.34-2.34).
Conclusions: Dopamine agonist therapy is associated with a decreased prevalence of residual tumour enlargement in patients with nonfunctioning pituitary adenomas, particularly when treatment is instituted before tumour remnant growth is detected.