Tumour growth rate improves tumour assessment and first-line systemic treatment decision-making for immunotherapy in patients with liver metastatic uveal melanoma.

BACKGROUND: The RECIST-based response variably matches the clinical benefit of systemic therapies for liver metastatic uveal melanoma (LMUM). The aims were to determine whether the tumour growth rate (TGR) can help predict the survival in patients with LMUM and to provide information for the management of first-line systemic treatment. METHODS: This retrospective study included 147 (training: n = 110, validation: n = 37) patients with LMUM treated with first-line systemic treatment between 2010 and 2021. Two TGR-derived parameters were calculated, TGR0 and TGR3m. Multivariate Cox analyses identified independent predictors of progression-free survival (PFS) and overall survival (OS). RESULTS: TGR3m was a strong independent prognostic factor of PFS and OS (p < 0.001). The RECIST-based response was no longer significant in the OS analyses. Only immunotherapy regimens correlated with higher OS (HR = 0.2; 95% CI, 0.1-0.5; p < 0.001) in the low-TGR3m (≤50%/m) subgroup. These findings were confirmed in the validation cohort. TGR0, disease-free interval (DFI), and the sum of target lesions at baseline were predictive factors of low TGR3m. DISCUSSION: The use of TGR3m would improve tumour assessment by identifying patients who would benefit from first-line immunotherapy regimens despite PD. TGR0, DFI and the sum of target lesions were correlated with TGR3m, which can support first-line treatment decision-making for immunotherapy.

Use of FDG-PET/CT for systemic assessment of suspected primary central nervous system lymphoma: a LOC study.

INTRODUCTION: Primary Central Nervous System Lymphoma (PCNSL) is a rare disease with different therapeutic implications than systemic lymphoma. In this study, we evaluated whole-body 18FDG-PET/CT for pre-chemotherapy imaging of suspected PCNSL. METHODS: One hundred and thirty consecutive immunocompetent patients were retrospectively included. The results of initial 18FDG-PET/CT, contrast-enhanced CT (CeCT) and bone marrow biopsy (BMB) when available were compared to a gold standard based on pathological diagnosis or follow-up. RESULTS: CNS lesion pathology showed large B-cell lymphoma in 95% of patients, including 11 patients with primary vitro-retinal lymphoma. Ten patients (8%) where ultimately diagnosed with systemic lymphoma involvement, including five pathologically confirmed cases, all of which were detected by 18FDG-PET/CT. 18FDG-PET/CT showed incidental systemic findings unrelated to lymphoma in 14% of patients. An SUVmax threshold of nine enabled good discrimination between systemic lymphoma and other lesions (sensitivity 92% and specificity 89%). CeCT and BMB performed in 108 and 77 patients respectively revealed systemic lesions in only three patients. CONCLUSION: 18FDG-PET/CT detected concomitant occult systemic involvement in a non-negligible proportion of suspected PCNSL cases (8%). In this setting its sensitivity is higher than that of CeCT. All of our patients ultimately diagnosed with concomitant systemic involvement had positive 18FDG-PET/CT. We believe it constitutes a safe one-stop shop evaluation for the systemic pre-treatment imaging of suspected PCNSL.