Radiation protection management in patients with stomas undergoing somatostatin receptor therapy with [177Lu]Lu-oxodotreotide.

Abstract

Somatostatin receptor therapy (SSRT) with [177Lu]Lu-oxodotreotide is an established treatment for metastatic neuroendocrine tumours. However, radiation protection guidelines for patients with stomas remain insufficiently addressed, particularly regarding the handling and disposal of contaminated stoma pouches. In this prospective study, three patients with established stomas underwent their first cycle of [177Lu]Lu-oxodotreotide therapy. Ex-vivo surface area activity and ambient dose equivalent rates of collected stoma pouches were measured over 168 h post-administration. All measurements were decay-corrected and evaluated against national exemption and clearance limits. Scenario-based calculations were performed to estimate municipal waste activity concentrations under different discharge timeframes. Marked inter-patient variability was observed. Patients 1 and 3 (nondrainable pouches) exhibited peak activity levels at ~45 h post-administration, followed by a gradual decline. In contrast, patient 2 (drainable pouch) showed a rapid decrease in activity because of daily liquid disposal. Estimated municipal waste activity concentrations for patients 1 and 2 were generally within national clearance limits. For patient 3, a nondrainable system represented a conservative worst-case scenario, where early discharge could potentially exceed clearance thresholds. Based on our findings, SSRT with [177Lu]Lu-oxodotreotide is feasible in patients with stomas when individualized radiation protection is applied. Although the study is limited by the small patient cohort, our results suggest that pouch type and excretion patterns are the primary determinants of waste radioactivity. A short-term hospitalization window (48-72 h) is recommended, particularly for patients using nondrainable stoma systems, to ensure regulatory compliance regarding waste disposal.