Abstract
BackgroundSomatostatin analogue-based radionuclide therapy with 177Lu-DOTATATE is an important treatment option for patients with advanced neuroendocrine tumours overexpressing somatostatin receptors. In addition to the kidneys, the bone marrow is a major dose-limiting organ. The correlation between developed haematological toxicity and absorbed dose to the bone marrow is poor, which indicates that other factors affect haematological response. The spleen has an important role in the haematopoetic system, including being a reservoir for blood cells. It is also the organ that receives the highest mean absorbed dose during 177Lu-DOTATATE treatment. The aim of this study was to analyse mean absorbed dose to the spleen and its correlation with haematological toxicity, and to explore changes in splenic volume.The study included 41 patients treated with 7.2 GBq (3.5–8.3 GBq) of 177Lu-DOTATATE on two to five occasions. Following each fraction, planar whole-body scans were acquired at 2, 24, 48, and 168 h, and a SPECT/CT at 24 h post-injection. Mean absorbed spleen dose was calculated utilising planar images for time-activity data and SPECT to adjust activity amounts. Splenic volume information was collected from diagnostic CT scans at baseline and follow-up.ResultsMedian and total absorbed spleen doses were estimated to 4.5 and 15 Gy, respectively. Total absorbed spleen dose correlated with decrease in Hb (p = 0.02), but not WBC (p = 0.31) or PLT (p = 0.65) counts. For patients without bone metastases, mean absorbed spleen dose correlated with decrease in PLT (p = 0.04) but not Hb (p = 0.16) or WBC (p = 0.42) counts. The spleen volume was reduced to 75 % (p < 0.001) of original values (200 vs. 260 ml) at a mean follow-up of 36 months.ConclusionsHaematological toxicity according to Hb counts was moderately but significantly correlated with total absorbed spleen dose. This supports the possibility that radiation exposure of the spleen affects overall haematological response during 177Lu-DOTATATE treatment.
Highlights
Somatostatin analogue-based radionuclide therapy with 177Lu-DOTATATE is an important treatment option for patients with advanced neuroendocrine tumours overexpressing somatostatin receptors
Somatostatin analogue-based PRRT using 177Lu-DOTATATE for patients with advanced neuroendocrine tumours that overexpress somatostatin receptors has become an established treatment option included in published guidelines [1]
Median absorbed dose was estimated to 4.7 Gy (1.5–10.6 Gy) per 7.4 GBq of 177Lu-DOTATATE (Fig. 2)
Summary
Somatostatin analogue-based radionuclide therapy with 177Lu-DOTATATE is an important treatment option for patients with advanced neuroendocrine tumours overexpressing somatostatin receptors. The correlation between developed haematological toxicity and absorbed dose to the bone marrow is poor, which indicates that other factors affect haematological response. The aim of this study was to analyse mean absorbed dose to the spleen and its correlation with haematological toxicity, and to explore changes in splenic volume. Somatostatin analogue-based PRRT using 177Lu-DOTATATE for patients with advanced neuroendocrine tumours that overexpress somatostatin receptors has become an established treatment option included in published guidelines [1]. The poor correlation between mean absorbed dose to the bone marrow and developed haematological toxicity in published studies [9, 10] is probably due to the fact that several factors influence haematological response. Earlier studies on haematological toxicity during 177Lu-DOTATATE treatment have revealed associations with renal function, tumour burden [11, 12], initial cytopenia [8, 11], previous chemotherapy, and patient age [11]
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