Abstract
Background: In addition to its SSTR-specific binding in tumors and healthy tissues, DOTATOC analogues accumulate in kidney parenchyma. Renal tracer uptake might be a surrogate of kidney function or dysfunction. This study aimed to evaluate if kidney function can be estimated from 68Ga[Ga]-DOTATOC uptake in PET/CT and its impact on the nephrotoxicity of 177Lu[Lu]-DOTATOC PRRT. Methods: Two cohorts of patients (A: 128 diagnostic patients; B: 32 PRRT patients) were evaluated retrospectively. SUV values of the kidneys, physiologically SSTR-expressing organs and in background compartments were assessed. Kidney function was calculated as eGFR by CKD-EPI creatinine equation. Pearson’s correlation coefficients and treatment-induced changes of uptake and kidney function were assessed and compared. Results: Kidney function and renal DOTATOC uptake showed a significant inverse correlation (R2 = 0.037; p = 0.029). Evaluated models of PET/CT measurements were not able to predict kidney function sufficiently. The uptake of other organs did not depend on eGFR. While the renal uptake increased after PRRT (p < 0.001), the kidney function did not change significantly (p = 0.382). Neither low pre-therapeutic eGFR nor high pre-therapeutic kidney uptake were risk factors of PRRT-induced deterioration in kidney function. Conclusion: The relevance of kidney function for renal 68Ga[Ga]-DOTATOC uptake is limited. The nephrotoxicity of 177Lu[Lu]-DOTATOC PRRT might be low and cannot be reliably predicted by pre-therapeutic measurements.
Highlights
Neuroendocrine tumors (NET), a rare group of tumors originating from the neural and endocrine cells, are mostly located in the gastrointestinal system or the lung [1]
Beta-emitter-labeled DOTA conjugates can be used for peptide receptor radionuclide therapy (PRRT) for metastasized NET, as recommended by guidelines in different clinical scenarios among other treatment options [5,6]
The aim of this study was to investigate the following questions dedicatedly for DOTATOC radiopharmaceuticals: Does a correlation between renal tracer uptake and kidney function exist? Can the kidney function be determined solely from the PET parameters? Does PRRT influence the kidney function, or solely the renal tracer uptake? Is it possible to predict the potential loss of function from pre-therapeutic tracer uptake?
Summary
Neuroendocrine tumors (NET), a rare group of tumors originating from the neural and endocrine cells, are mostly located in the gastrointestinal system or the lung [1]. Radiolabeled somatostatin analogues are established radiopharmaceuticals in diagnostics and the treatment of NET and especially target the SSTR subtype 2 [2]. During the last 20 years, 68 Ga-DOTA conjugates became widely available and superseded 111 In-octreotides in tumor detection rate and renal uptake [3]. Nowadays, they are widely used for positron emission tomography/computed tomography (PET/CT) diagnostics in different issues such as tumor staging, or pre- and post-therapeutic evaluation. This study aimed to evaluate if kidney function can be estimated from 68 Ga[Ga]-DOTATOC uptake in PET/CT and its impact on the nephrotoxicity of 177 Lu[Lu]DOTATOC PRRT.
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