If biochemical control of acromegaly is not achieved by operation and medication, radiotherapy may be indicated.
To describe fractionated radiotherapy (FRT) and stereotactic radiosurgery (SRS) regarding excess of IGF-1 and pituitary function.
Design and methods
A retrospective analysis of 352 patients (4126 patient-years) from the German Acromegaly Registry was performed. Follow-up was 1.0–45.1 years after radiotherapy. Therapeutic success was defined by low or normal IGF-1 according to center-specific reference ranges without (= remission) or on (= controlled disease) suppressive medication.
Time between radiotherapy and last follow-up was 13.0 ± 8.2 years for FRT (n = 233) and 8.9 ± 5.0 years for SRS (n = 119, P < 0.001). Median (IQR) basal growth hormone before radiotherapy was 6.3 (2.9–16.2) ng/mL for FRT and 3.5 (1.8–6.9) ng/mL for SRS (P < 0.001). Mean time in uncontrolled state was 3.0 years after FRT and 2.1 years after SRS (95% CI for the difference is 0.1 to 1.6 years, P = 0.021). The 10-year calculated remission rate was 48% for FRT and 52% for SRS (95% CI for the difference is −18 to 26% age points, P = 0.74) and the respective controlled disease rate was 23 and 26%. The odds ratio for adrenocorticotropic or thyreotropic insufficiency was 0.54 (95% CI: 0.30–1.00, P = 0.049) in SRS compared to FRT patients.
Both after FRT and SRS about 75% of patients with acromegaly are in remission or controlled after 10 years. A slightly faster achievement of target values was observed after SRS. The rate of pituitary insufficiency in FRT patients is significantly higher.
Supplement: additional analyses
Supplementary table 1: Baseline demographic and clinical characteristics. Entries are mean ± standard deviation, median [interquartile range] or numbers (\%). The p-values are for a global test of a difference depending on radiotherapy methods and are based on ANOVA for continuous variables and exact tests for the contingency table. The ANOVA for growth hormone (GH) was performed after logarithmic transformation of the values.