Pituitary Function after High-Dose 177Lu-DOTATATE Therapy and Long-Term Follow-Up

Area of Science:

• Endocrinology
• Nuclear Medicine
• Oncology

Background:

• The pituitary gland expresses somatostatin receptors, making it susceptible to radiation toxicity from 177Lu-DOTATATE.
• Neuroendocrine tumors (NETs) are often treated with 177Lu-DOTATATE, necessitating an understanding of potential side effects.

Purpose of the Study:

• To investigate pituitary function changes in NET patients after dosimetry-based 177Lu-DOTATATE therapy.
• To identify potential late toxicities and their correlation with radiation dose.

Main Methods:

• Analysis of 68 patients from a phase II clinical trial receiving individualized 177Lu-DOTATATE therapy.
• Longitudinal assessment of the GH/IGF-1, gonadotropin, adrenal, and thyroid axes over a median follow-up of 30 months.
• Statistical analysis using linear mixed models and correlation of pituitary absorbed dose with IGF-1 changes.

Main Results:

• A significant decrease in Insulin-like Growth Factor 1 (IGF-1) levels was observed (p < 0.005), correlating with treatment cycles and absorbed radiation dose.
• Gonadotropin levels showed a non-significant decrease in postmenopausal women and transient increase in men.
• No significant changes were noted in adrenal or thyroid axes.

Conclusions:

• 177Lu-DOTATATE therapy can induce radiation-related damage to the pituitary gland, primarily affecting the GH/IGF-1 axis.
• While no severe endocrine disorders were detected, dosimetric analysis supports pituitary toxicity.
• Monitoring pituitary function is crucial in patients undergoing this treatment.