Introduction: Invasive GH-secreting pituitary adenomas are rarely cured by surgery and although long-term therapy with somatostatin analogs (SSAs) may be employed, hormonal control is achieved in only 60% of cases. The impact of tumor debulking on subsequent control of acromegaly with SSAs has not been studied previously. Methods: We studied retrospectively the response to SSA therapy in acromegalic patients before and after incomplete surgical tumor excision. A case review identified 24 acromegalic patients who had received SSA therapy for $1 month before and after gross total resection or debulking of adenomas. No patient received radiotherapy or combination treatment with SSAs and dopamine agonists during the study. GH and IGF-I responses to SSAs were recorded pre-and postoperatively. Postoperative SSA therapy was begun after a washout period of 1-3 months to assess the hormonal effects of the surgery alone. Results: Before preoperative SSA treatment, 24/24 (100%) patients had elevated GH levels and IGF-I levels were elevated in 19/21 (90.5%) patients with recorded values. During preoperative SSA treatment, GH and IGF-I levels were normalized in 7/24 (29.2%) and 11/24 (45.8%) patients respectively. Following postoperative washout, GH was controlled in only 3/24 (12.5%) patients, while IGF-I was controlled in 8/19 (42.1%) patients with available data. During the second SSA treatment period, normal GH levels were seen in 13/24 (54.2%) patients, while IGF-I control was noted in 18/23 (78.3%). Conclusion: Gross total tumor resection or debulking increases the likelihood of achieving biochemical disease control with SSAs in acromegalic patients with adenomas that were not amenable to complete surgical resection and in whom primary SSA therapy was unable to achieve good biochemical control.

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