Mantle cell lymphoma (MCL) is an aggressive lymphoma subtype with poor prognosis in which 18F-FDG-PET/CT role in treatment response evaluation and prediction of outcome is still unclear. The aim of this multicentric study was to investigate the role of 18F-FDG-PET/CT in staging MCL and the prognostic role of Deauville criteria (DC) in terms of progression-free survival (PFS) and overall survival (OS). We retrospectively enrolled 229 patients who underwent baseline and end-of-treatment (eot) 18F-FDG-PET/CT after first-line therapy. EotPET/CT scans were visually interpreted according to DC. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT for evaluation of bone marrow (BM) were 27%, 100%, 100%, 48% and 57%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT for evaluation of the gastrointestinal (GI) tract were 60%, 99%, 93%, 90% and 91%, respectively. At a median follow-up of 40 months, relapse occurred in 104 cases and death in 49. EotPET/CT results using DC significantly correlated with PFS, not with OS. Instead, considering OS, only MIPI score was significantly correlated. In conclusion, we demonstrated that MCL is an FDG-avid lymphoma and 18F-FDG-PET/CT is a useful tool for staging purpose, showing good specificity for BM and GI evaluation, but suboptimal sensitivity. EotPET/CT result was the only independent significant prognostic factor that correlated with PFS.

Peptide receptor radionuclide therapy (PRRT) is an effective therapeutic option in patients with metastatic neuroendocrine tumor (NET). However, PRRT fails in about 15–30% of cases. Identification of biomarkers predicting the response to PRRT is essential for treatment tailoring. We aimed to evaluate the predictive and prognostic role of semiquantitative and volumetric parameters obtained from the 68Ga-DOTATOC PET/CT before therapy (bPET) and after two cycles of PRRT (iPET). A total of 46 patients were included in this retrospective analysis. The primary tumor was 78% gastroenteropancreatic (GEP), 13% broncho-pulmonary and 9% of unknown origin. 35 patients (76.1%) with stable disease or partial response after PRRT were classified as responders and 11 (23.9%) as non-responders. Logistic regression analysis identified that baseline total volume (bTV) was associated with therapy outcome (OR 1.17; 95%CI 1.02–1.32; p = 0.02). No significant association with PRRT response was observed for other variables. High bTV was confirmed as the only variable independently associated with OS (HR 12.76, 95%CI 1.53–107, p = 0.01). In conclusion, high bTV is a negative predictor for PRRT response and is associated with worse OS rates. Early iPET during PRRT apparently does not provide information useful to change the management of NET patients.

Discordant results have been generated regarding the prognostic role of Total Metabolic Tumor Volume (TMTV) in Follicular Lymphoma (FL). The use of prospective data and the adoption of the newly defined standardized SUV4 method for calculating TMTV may generate stronger evidence. We conducted a pre‐planned post hoc analysis of the prospective multicenter randomized phase III FOLL12 trial for newly diagnosed high tumor burden FL (grade 1–3a), which mandated baseline staging with PET. Baseline PET/CT scans were reviewed centrally, and TMTV was calculated using the fixed threshold of SUV4. Kaplan–Meier and Cox regression were used for survival analysis. The primary study endpoint was Progression free Survival (PFS). A total of 689 FL patients were available for TMTV definition. Median TMTV was 161 mL (IQR 50 to 388 mL) and the best cutoff value was set at 180 mL. Patients with high TMTV had a significantly lower 5‐year PFS compared to those with low TMTV: 59% (95% CI, 53–65%) vs. 74% (95% CI, 69–78%) HR 1.61 (95% CI, 1.24–2.09). Prognostic role of TMTV was independent of study arm, chemotherapy regimen, and FLIPI2. Combined with FLIPI‐2, we identified three groups with different 5‐yr PFS rates, with the lowest rates (51%) for patients with high TMTV and high FLIPI2. Combined TMTV and FLIPI model was also prognostic to predict the risk of early progression and of death. Applying the SUV4 standard method pre‐treatment TMTV is confirmed as a strong and independent predictor of PFS in FL patients. Integrating TMTV with FLIPI‐2 improves risk assessment.