“…In the largest study with 338 patients and a 20-year follow-up period the 10-year progression-free survival for non-secreting adenomas was 97%, compared to 89% in secreting adenomas (significance of p < 0.005) [13] and in the study from McCord et al [64] a trend has been described with p = 0.079. Radiotherapy alone can reduce and control the prolactin levels in 44-79% [7,30,91,102], somatomedin-C and GH levels in 70-90% [38,55,70,71,84,102] and hypercortisolism in 50-100% [22,25,29,38,45,48,64,68,102]. Although there is a considerable delay before response is obtained, GH levels decrease to a rate of 10-30% per year and ACTH remissions were achieved 6-60 months after irradiation and in most cases during the first 2 years [38,55,70,71,82,84,102].…”