Long-term results of fractionated stereotactic radiotherapy as third-line treatment in acromegaly

Abstract

The treatment of acromegaly is based on surgery, drugs, and radiotherapy as a third-line option. Fractionated stereotactic radiotherapy (FSRT) is a new technique with a need for long-term evaluation. The purpose of the study was to evaluate long-term results of FSRT in acromegaly. Overall, 34 patients [sex ratio 1.12, age 45 (5-65) years] with a pituitary adenoma of 24.5 (9-76) mm including 20 invasive tumors were treated by radiotherapy in fractionated stereotactic conditions delivering 50 gy in 27 sessions. Baseline growth hormone (GH) and IGF1 levels were 18 (±14.5) and 632.6 (±339) µg/L, respectively. Indications of FSRT were failure of surgery and drug treatments (n = 30) or contraindication/refusal of surgery (n = 4). Hormonal control was defined by normal age- and sex-adjusted IGF1. Remission was defined by hormonal control after withdrawal of drugs for a minimum of three consecutive months. Data were analyzed in SPSS software with a significance level at p < 0.05. After a mean follow-up of 152 months, hormonal control was achieved in 33 patients (97 %) with withdrawal of drugs in 13 patients (38.2 %) without any recurrence. Factors found to be significantly associated to remission in a multivariate Cox regression were lower baseline hormone levels (GH and IGF1) and smaller tumor size. Tumor control was achieved in all patients. Acquired hypopituitarism after radiotherapy was the main side effect reported with a rate of 39 %. FSRT seems to be an effective and well tolerated third-line treatment of acromegaly, particularly adapted to macro adenomas treatment.

Ischemic stroke after radiation therapy for pituitary adenomas: a systematic review

“…Not all included studies describe the duration of follow-up. The shortest follow-up was 14 months (range 1–49) and the longest follow-up was 152 months [ 5 , 18 ].…”

“…The radiotherapy dosage administered in the conventional therapy group ranged from 36 to 62 Gy, delivered in 20–25 fractions over a period of 5 weeks (Table 2 ). Five studies described the use of stereotactic or gamma knife radiosurgery (SRS or GKS) [ 6 , 17 , 18 , 22 , 24 ]. These were relatively smaller case series with 27 to 53 patients.…”

“…Single fraction high doses of radiation were used in the studies that described GKS, with a median single dose of 15 Gy given in ten shots per fraction (range 5–15) [ 17 ] and a mean dose of 20.2 Gy (>110 Gy EQD2) [ 22 ]. The remaining studies used fractionated stereotactic radiotherapy (FSRT) with mean/median doses ranging from 45 to 50 Gy in 25–30 fractions [ 6 , 18 , 24 ].…”

“…Only three studies indicated timing of radiotherapy (Table 2 ) [ 17 , 18 , 24 ]. As most studies were retrospective case series of radiated pituitary adenoma patients, it was not indicated whether the pituitary adenomas were newly diagnosed.…”

Fractionated stereotactic radiotherapy: an interesting alternative to stereotactic radiosurgery in acromegaly

“…Its efficacy and tolerability have so far only been evaluated in a few studies with short follow-up [8][9][10][11]. The paper by Diallo AM et al in this issue of Endocrine provides valuable information on the long-term effects of FSRT on hormonal status and tumor volume, and adverse effects, in a series of 34 acromegalic patients, 32 of whom had macro-or invasive GH-secreting adenomas [12]. The study was performed in a single center, thus avoiding inter-center variability and enhancing the validity of the results.…”