Introduction: CyberKnife (CK) is an emerging treatment for pituitary tumours (PT) resistant to other therapies.
Patients and methods: We report long-term CK effect on endocrine function and tumour volume in 20 PT patients (11M/10F, mean age 58.6±14.4years). Twelve patients harboured a non functioning adenoma, 2 an ACTH, 5 a GH (one case of TSH co-secretion) and 2 a PRL-secreting PT. Before CK nine patients had normal while 11 presented impaired pituitary function. CK was used as first line treatment in three cases. The mean follow-up period was 21.16±16.35 months (range, 290 months).
Results: MRI demonstrated tumour shrinkage in 50% of patients. Tumour increase was evident only in two cases. Pituitary function impairment occurred in three of the nine patients with previous normal pituitary function who developed isolated deficiency in two cases and multiple deficiencies in 1. Among six patients with previously multiple or isolated hypopituitarism, two became panhypopituitary and one developed a new deficit.
Conclusions: CK treatment for PT is safe and effective, ceasing tumour growth in 90%, and inducing tumour shrinkage in 50% of cases. Nevertheless, impairment of pituitary secretion was demonstrated in 30% of cases with previously intact pituitary function and in 50% of already hypopituitary patients.