ESTRO 2024 - Abstract Book

S942

Clinical - CNS

ESTRO 2024

All tumors were initially in contact with optical system. 62% (n=13) had pre-existing optical deficits, 71% (n=15) partial endocrine dysfunctions.

Clinical Target Volume 1 (CTV1) included tumor and pre-op extent (anatomically adapted). With doses >54Gy, a CTV2 (=Gross Tumor Volume GTV) was also defined, Planning Target Volume (PTV) margin was 3mm. Median dose was 54GyRBE (54-66 GyRBE) in 27-33 fractions; 5 patients with higher grade histology and/or extensive skull base infiltration received 54-66 GyRBE (median dose 60 GyRBE). Median D1% on optical structures was 54GyRBE (49-60 GyRBE). A representative treatment plan and associated target and normal tissue values are illustrated below. After PT, patients are regularly followed up either by telephone (after sending images and reports) or with the relevant documents on site. Follow-up care is arranged 3, 6 and 12 months after therapy and annually thereafter. Tumor response was assessed by MRI, toxicity by CTCAE V4.0.

Results:

With a median follow-up of 37.5 months (max. 62 months), local tumor control rate was 100%. There was no acute or early-late toxicity above or equal to G3 observed in the cohort. Pre-existing visual deficits did not change significantly and no new vision deficits appeared. One patient (4.8%) had significant changes in hormonal functioning with reduction in cortisol level firstly measured about 1 month after PT. In this patient, hormonal dysfunction with low prolactin levels were known before start of PT. With hormone replacement therapy values normalized without complications or necessity of hospitalization.

Conclusion:

With a follow-up of > 3 years after fractionated proton therapy, patients with locally aggressive pituitary macroadenomas have excellent local tumor control rates with preservation of visual functions.