Disease remission in long term treated acromegalic patients after somatostatin analog withdrawal
CL Ronchi1, V Varca1, A Lania1, M Arosio2, A Spada1 & P Beck-Peccoz1
Long acting somatostatin analogs (SSTa) induce both GH/IGF-I reduction and pituitary tumor volume shrinkage in the majority of acromegalic patients. It is not known if SSTa might also definitively cure the acromegalic disease in at least some patients. Aim of the present study was to evaluate this possibility in acromegalic patients very well responsive to chronic treatment. Thirteen acromegalic patients (4M&9F), 5 newly diagnosed and 8 previously operated but none irradiated, treated with SSTa (6 with octreotide-LAR, 4 with lanreotide-SR and 3 with lanreotide-Autogel) for a median period of 51 months (range: 18156 months) were studied. All these patients were highly responsive to the treatment on the basis of hormonal (GH <2.5 μg/l and normal IGF-I levels) and tumor volume response (reduction or absence of tumor mass). None of them underwent radiotherapy during SSTa treatment. In all patients, basal GH, post-glucose GH nadir levels, IGF-I concentrations and symptoms score were studied after short-term drug withdrawal (median: 3 months). During this period, 4 patients relapsed, 9 maintained GH <2.5 μg/l (mean: 1.8±0.6 vs pre-therapy 6.0±3.6 μg/l, P<0.05), 5 of them with postglucose GH <1 μg/l. Three of these patients, all previously operated, also had normal IGF-I (mean: +0.4±0.3 vs pre-therapy +4.4±2.2 SDS, P<0.05) and absence of acromegaly-related symptoms. These 3 patients had lower IGF-I levels during therapy in respect to the other ones (−1.1±0.8 vs +0.4±1.0 SDS, P<0.05). The cured patients are currently in drug suspension and still had postglucose GH <1 μg/l and normal IGF-I levels after 6 (n=2) and 30 months (n=1) from SSTa withdrawal. In conclusion, SSTa therapy seems to be able to induce at least a 6-month disease remission in some very well controlled acromegalic patients, a figure that increases if only postoperative patients are taken into account and suggests the utility of a periodical drug suspension in these subjects. Moreover, IGF-I appeared the main predictive parameter of hormonal control even after SSTa withdrawal.