Baseline body composition and early PRRT outcome in GEP-NETs: an exploratory analysis.

Abstract

Early progression after PRRT occurs in a subset of patients with somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Associations between body composition and early PET-based progression after PRRT were assessed. In this retrospective analysis, 321 patients undergoing PRRT were screened. Body composition parameters were assessed on the CT component at the L3/L4 level. Myosteatosis was defined using BMI-adjusted psoas muscle attenuation cut-offs. The primary endpoint was early SSTR-targeted PET-based progression after up to four consecutive PRRT cycles, dichotomized as progressive disease versus disease control, which was available in 301 patients. Early PET-based progression occurred in 24/301 patients (8.0%). Traditional quantity-based body composition parameters were not associated with early progression. Baseline myosteatosis was present in only 8/301 patients (2.7%) and showed a nominal association with early progression in univariable analysis (OR 7.8, 95% CI 1.74-34.78; p = 0.0073), but this association did not remain significant after Benjamini-Hochberg correction for multiple testing (FDR-adjusted p = 0.1073). In a separately specified baseline-adjusted model, myosteatosis remained nominally associated with early progression (OR 8.1, 95% CI 1.69-38.75; p = 0.0090). In an exploratory model additionally including the number of completed PRRT cycles as a post-baseline treatment-exposure variable, the association was attenuated and narrowly missed conventional statistical significance (OR 5.7, 95% CI 0.97-32.86; p = 0.0538). Traditional quantity-based body composition parameters were not associated with early PET-based progression after PRRT. Although baseline myosteatosis showed a nominal association with early progression, this finding was based on only eight patients and did not remain significant after correction for multiple testing. The results should therefore be regarded as exploratory and hypothesis-generating and do not establish clinical utility of myosteatosis for individual risk stratification.