AIM: To examine the role of [18F]FDG PET/CT for assessing response to immunotherapy in patients with some solid tumors. METHODS: Data recorded in a multicenter (n = 17), retrospective database between March and November 2021 were analyzed. The sample included patients with a confirmed diagnosis of a solid tumor who underwent serial [18F]FDG PET/CT (before and after one or more cycles of immunotherapy), who were >18 years of age, and had a follow-up of at least 12 months after their first PET/CT scan. Patients enrolled in clinical trials or without a confirmed diagnosis of cancer were excluded. The authors classified cases as having a complete or partial metabolic response to immunotherapy, or stable or progressive metabolic disease, based on a visual and semiquantitative analysis according to the EORTC criteria. Clinical response to immunotherapy was assessed at much the same time points as the serial PET scans, and both the obtained responses were compared. RESULTS: The study concerned 311 patients (median age: 67; range: 31–89 years) in all. The most common neoplasm was lung cancer (56.9%), followed by malignant melanoma (32.5%). Nivolumab was administered in 46.3%, and pembrolizumab in 40.5% of patients. Baseline PET and a first PET scan performed at a median 3 months after starting immunotherapy were available for all 311 patients, while subsequent PET scans were obtained after a median 6, 12, 16, and 21 months for 199 (64%), 102 (33%), 46 (15%), and 23 (7%) patients, respectively. Clinical response to therapy was recorded at around the same time points after starting immunotherapy for 252 (81%), 173 (56%), 85 (27%), 40 (13%), and 22 (7%) patients, respectively. After a median 18 (1–137) months, 113 (36.3%) patients had died. On Kaplan–Meier analysis, metabolic responders on the first two serial PET scans showed a better prognosis than non-responders, while clinical response became prognostically informative from the second assessment after starting immunotherapy onwards. CONCLUSIONS: [18F]FDG PET/CT could have a role in the assessment of response to immunotherapy in patients with some solid tumors. It can provide prognostic information and thus contribute to a patient’s appropriate treatment. Prospective randomized controlled trials are mandatory.

Introduction: Nasopharyngeal carcinoma (NPC) is a distinct malignancy of the head and neck with high prevalence in endemic regions and a strong association with Epstein–Barr virus (EBV). In locally advanced stages, neoadjuvant chemotherapy (NAC) followed by chemoradiotherapy improves outcomes, but response rates vary. Identifying early predictors of NAC response is essential for guiding personalized treatment strategies. This study aims to assess whether baseline [¹⁸F]FDG PET/CT parameters can predict NAC response in NPC patients. Methods: In this retrospective study, 27 patients with histologically confirmed, locally advanced (stage III) NPC underwent baseline [¹⁸F]FDG PET/CT prior to NAC between 2015 and 2023. Quantitative PET parameters including SUVmax, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were extracted from the primary tumor. NAC response was assessed using RECIST 1.1 criteria and classified as responders (CR + PR) or non-responders (SD + PD). Group comparisons were performed using Student’s t-test. ROC analysis was used to identify optimal cut-off values. A p-value < 0.05 was considered significant. Results: The cohort included 20 males and 7 females (mean age: 60.8 ± 15.2 years). The predominant histotype was undifferentiated non-keratinizing carcinoma (92.6%). A total of 19 patients (70.4%) responded to NAC. Responders had significantly lower baseline SUVmax (10.9 ± 4.8 vs. 15.8 ± 4.1, p = 0.021), MTV (16.2 ± 12.4 vs. 27.8 ± 19.5 cm³, p = 0.045), and TLG (128.6 ± 98.2 vs. 218.7 ± 152.4, p = 0.038). SUVmean was also lower in responders (6.1 ± 2.1 vs. 9.3 ± 2.8), although not statistically reported. ROC analysis identified SUVmax > 12.5 and MTV > 20.0 cm³ as thresholds associated with poor NAC response. Conclusions: Baseline metabolic parameters from [¹⁸F]FDG PET/CT, particularly SUVmax and MTV, may assist stratification of NAC response in nasopharyngeal carcinoma. These biomarkers may facilitate pre-treatment stratification and guide more personalized therapeutic approaches. However, the limited sample size may affect the generalizability of these findings, and larger prospective studies are needed to confirm the results.

CAR-T-cell therapy, also referred to as chimeric antigen receptor T-cell therapy, is a novel method in the field of immunotherapy for the treatment of non-Hodgkin’s lymphoma (NHL). In patients receiving CAR-T-cell therapy, fluorodeoxyglucose Positron Emission Tomography/Computer Tomography ([¹⁸F]FDG PET/CT) plays a critical role in tracking treatment response and evaluating the immunotherapy’s overall efficacy. The aim of this study is to provide a systematic review of the literature on the studies aiming to assess and predict toxicity by means of [¹⁸F]FDG PET/CT in patients with NHL receiving CAR-T-cell therapy. PubMed/MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases were interrogated by two investigators to seek studies involving the use of [¹⁸F]FDG PET/CT in patients with lymphoma undergoing CAR-T-cell therapy. The comprehensive computer literature search allowed 11 studies to be included. The risk of bias for the studies included in the systematic review was scored as low by using version 2 of the “Quality Assessment of Diagnostic Accuracy Studies” tool (QUADAS-2). The current literature emphasizes the role of [¹⁸F]FDG PET/CT in assessing and predicting toxicity in patients with NHL receiving CAR-T-cell therapy, highlighting the evolving nature of research in CAR-T-cell therapy. Additional studies are warranted to increase the collected evidence in the literature.

Background: This meta-analysis compared the diagnostic performance of [¹⁸F] fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT) or PET versus Magnetic resonance imaging (MRI) in detecting recurrence or residual tumors at the primary site in patients with nasopharyngeal carcinoma (NPC). Methods: A comprehensive literature search was conducted in the PubMed/MEDLINE and CENTRAL databases to find studies with at least 20 patients with NPC undergoing both [¹⁸F]FDG PET/CT (or [¹⁸F]FDG PET) and MRI for detecting recurrence or assessing residual disease at the primary site. The pooled sensitivity and specificity of PET/CT and MRI were calculated with 95% confidence intervals (CIs) and compared. Results: Five studies, including 1908 patients (six patient groups), were included. PET imaging had higher sensitivity [93.3% (95% CI: 91.3–94.9%); I² = 52.6%] compared to MRI [80.1% (95% CI: 77.2–82.8%); I² = 68.3%], but the specificity of the two modalities was similar: 93.8% (95% CI: 92.2–95.2%; I² = 0%) for PET/CT and 91.8% (95% CI: 90.1–93.4%; I² = 94.3%) for MRI. The areas under the curve (AUCs) for PET/CT and MRI were 0.978 and 0.924, respectively, without significant difference (p = 0.23). Conclusions: This meta-analysis suggests that [¹⁸F]FDG PET imaging and MRI do not significantly differ in diagnostic performance. Nevertheless, [¹⁸F]FDG PET imaging shows higher sensitivity than MRI.

Introduction: Fluorodeoxyglucose (FDG) PET/CT is typically the reference imaging method for assessing and tracking lymphomas. However, fibroblast activation protein inhibitor (FAPI) PET is being explored as a potentially useful option, especially when Fluorodeoxyglucose (FDG) scans do not show clear results.Methods: For this systematic review, two researchers searched PubMed/MEDLINE and Cochrane CENTRAL for studies on FAPI PET/CT in lymphoma patients.Results: The literature search initially retrieved 249 articles. After removing duplicates and screening titles and abstracts, and full text, there was a final selection of 15 articles (3 original studies and 12 case reports), encompassing a total of 270 patients. The three original studies were judged to have a low risk of bias according to the QUADAS-2 criteria. The systematic review reveals that FAPI PET/CT exhibits lower diagnostic sensitivity than [¹⁸F]FDG PET/CT in lymphomas characterized by low FAP expression. Nevertheless, FAPI PET/CT retains potential as a complementary imaging modality.Discussion: [¹⁸F]FDG PET/CT remains the gold standard in lymphoma imaging, but FAPI PET/CT can potentially provide supplementary information regarding the molecular characteristics of lymphomas. FAPI PET/CT may have prognostic and therapeutic implications. In particular, it could help identify lymphoma subgroups with distinct stromal environments, potentially serving as a prognostic biomarker. Further large-scale prospective studies are warranted to validate its role in lymphoma management.

Background: The aim of this study was to investigate whether high body mass index (BMI) increases the risk of recurrence and correlates with higher glucose uptake in recurrent lesions in post-menopausal female patients with breast cancer. Methods: A hospital database was searched to retrieve breast cancer patients who had undergone an [¹⁸F]FDG PET/CT scan before neoadjuvant chemotherapy and curative-intent surgery. BMI was calculated at the baseline [¹⁸F]FDG PET/CT scan. There was a median follow-up of 5 years after the baseline PET/CT scan to identify recurrence in the breast (T_rec); lymph nodes (N_rec); and distant locations (M_rec). Furthermore, SUVmax was measured at the sites of recurrence. A chi-square test was used to investigate any difference in the frequency of any recurrence, T_rec, N_rec, and M_rec, between overweight women (BMI ≥ 25 kg/m²) and women with a BMI < 25 kg/m² (p < 0.05). SUVmax was compared using a t-test (p < 0.05) between the two groups. Results: A total of 142 post-menopausal patients (BMI: 26.84 ± 5.59; 84 overweight and 58 with normal weight) were retrieved from the database. There were 48 recurrences at the follow-up. The chi-square test demonstrated in overweight women an increased frequency of any recurrence (35 vs. 13; p = 0.025) and T_rec (15 vs. 2; p = 0.018) and a higher T_rec SUVmax (4.74 ± 2.90 vs. 1.85 ± 0.63; p = 0.09) compared to women with a BMI < 25 kg/m². Conclusions: BMI seems to correlate with an increased rate of recurrence, especially in the breast, and a higher glucose uptake in post-menopausal patients with recurrent breast cancer.