Diagnostic and prognostic impact of 18F-FDG PET/CT in follicular lymphoma. Eur J Nucl Med Mol Imaging. 2010;37:2307-2314. [PMID: 20717826 DOI: 10.1007/s00259-010-1539-5]

Diagnosis, management and follow-up of follicular lymphoma: a consensus practice statement from the Australasian Lymphoma Alliance

Follicular lymphoma (FL) is the most common indolent non-Hodgkin lymphoma subtype, accounting for 15-20% of all lymphoma diagnoses. Although typically slow-growing and responsive to frontline therapies, advanced-stage FL remains incurable with current treatments and typically follows a chronic relapsing/remitting course with increasingly shorter responses to subsequent lines of therapy. Outcomes are highly variable; some patients experience prolonged first remissions that may approximate a 'functional cure'. By contrast, a significant minority of patients experience disease progression shortly after frontline treatment resulting in high rates of lymphoma-related mortality. Reflecting on the heterogeneous natural history of FL, clinical practice varies widely, particularly in controversial areas, including appropriate disease staging, selection of management strategies and duration of clinical follow-up. This position statement presents an evidence-based synthesis of the literature for application in Australasian practice.

End-of-treatment 18[F]-FDG PET can predict early progression in patients receiving bendamustine-rituximab for follicular lymphoma in first relapse: a prospective West Japan hematology Study Group (W-JHS) NHL01 trial

Response determined by 18[F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET)-CT after induction therapy can predict progression-free survival (PFS) in follicular lymphoma (FL). However, little prospective research has examined the significance of PET after second-line therapy. We conducted a prospective multicenter phase II trial (W-JHS NHL01) of bendamustine plus rituximab (BR) without rituximab maintenance for FL in first relapse. This study aimed to evaluate the usefulness of end-of-treatment (EOT)-PET for predicting PFS in FL patients in first relapse. EOT-PET examinations were performed between 6 and 8 weeks from the start of the last BR cycle. The primary endpoint was 1-year PFS. Key secondary endpoints were overall response rate (ORR), complete response rate (CRR), and 1-year overall survival (OS). Seventy-five patients were enrolled, and 8 were excluded from analysis. ORR was 86.6% and CRR was 59.7%. One-year PFS was 88.9% (95% confidence interval [CI] 80.7-94.3%) and 1-year OS in 75 patients was 97.3% (95% CI 89.6-99.3%). One-year PFS was significantly inferior in EOT-PET-positive patients (n = 9) compared with PET-negative patients (n = 58) (77.8% vs. 93.1%; p = 0.02). We confirmed that EOT-PET after second-line BR therapy could predict early progression in FL patients in first relapse.

Prognostic value of the combination of volume, massiveness and fragmentation parameters measured on baseline FDG pet in high-burden follicular lymphoma

The prognostic value of radiomic quantitative features measured on pre-treatment 18F-FDG PET/CT was investigated in patients with follicular lymphoma (FL). We conducted a retrospective study of 126 FL patients (grade 1-3a) diagnosed between 2006 and 2020. A dozen of PET/CT-derived features were extracted via a software (Oncometer3D) from baseline 18F-FDG PET/CT images. The receiver operating characteristic (ROC) curve, Kaplan-Meier method and Cox analysis were used to assess the prognostic factors for progression of disease within 24 months (POD24) and progression-free survival at 24 months. Four different clusters were identified among the twelve PET parameters analyzed: activity, tumor burden, fragmentation-massiveness and dispersion. On ROC analyses, TMTV, the total metabolic tumor volume, had the highest AUC (0.734) followed by medPCD, the median distance between the centroid of the tumors and their periphery (AUC: 0.733). Patients with high TMTV (HR = 4.341; p < 0.001), high Tumor Volume Surface Ratio (TVSR) (HR = 3.204; p < 0.003) and high medPCD (HR = 4.507; p < 0.001) had significantly worse prognosis in both Kaplan-Meier and Cox univariate analyses. Furthermore, a synergistic effect was observed in Kaplan-Meier and Cox analyses combining these three PET/CT-derived parameters (HR = 12.562; p < 0.001). Having two or three high parameters among TMTV, TVSR and medPCD was able to predict POD24 status with a specificity of 68% and a sensitivity of 75%. TMTV, TVSR and baseline medPCD are strong prognostic factors in FL and their combination better predicts disease prognosis.

Positron emission tomography to detect bone marrow involvement for patients with follicular lymphoma: a systematic review and meta-analysis

Detection of bone marrow involvement (BMI) for patients with follicular lymphoma (FL) is of great significance for staging and treatment. The clinical value of positron emission tomography/computed tomography (PET/CT) in assessing BMI is still under debate and investigation. PubMed, Embase, Web of Science, and Cochrane Library databases were systematically searched to identify studies evaluating PET/CT in detecting BMI in FL patients. Data extraction and quality evaluation were independently conducted by two reviewers, and nine eligible studies were selected as final quantitative analysis. Nine studies comprising 1119 FL patients were included. The pooled sensitivity was 0.67 (95% CI, 0.38-0.87), and the pooled specificity was 0.82 (95% CI, 0.75-0.87). The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 3.7 (95% CI, 2.1-6.3), 0.4 (95% CI, 0.18-0.91), and 9 (95% CI, 2-33), respectively. The area under the curve of PET/CT to detect BMI in FL patients was 0.83 (95% CI, 0.8-0.86). Current evidence suggests that PET/CT cannot replace bone marrow biopsy to detect BMI, but it is still of partial clinical significance for the prognosis of patients with follicular lymphoma.

Accuracy and prognostic impact of FDG PET / CT and biopsy in bone marrow assessment of follicular lymphoma at diagnosis: A Nation‐Wide cohort study

BACKGOUND

In the workup of follicular lymphoma (FL), bone marrow biopsy (BMB) assessment is a key component of FLIPI and FLIPI2, the most widely used outcome scores. During the previous decade, several studies explored the role of FDG-PET/CT for detecting nodal and extranodal disease, with only one large study comparing both techniques.

METHODS

The aim of our study was to evaluate the diagnostic accuracy and the prognostic impact of both procedures in a retrospective cohort of 299 FL patients with both tests performed at diagnosis. In order to avoid a collinearity bias, FLIPI2 was deconstructed in its founding parameters, and the bone marrow involvement (BMI) parameter separately included as: a positive BMB, a positive PET/CT, the combined "PET/CT and BMB positive" or "PET/CT or BMB positive". These variables were also confronted independently with the POD24 in 233 patients treated with intensive regimens.

RESULTS

In the total cohort, bone marrow was involved in 124 and 60 patients by BMB and PET/CT, respectively. In terms of overall survival, age > 60 y.o. and the combined "PET/CT or BMB positive" achieved statistical independence as a prognostic factor. In patients treated with an intensive regimen, only the combined "PET/CT or BMB positive" added prognostic value for a shorter overall survival, when confronted with the POD24.

CONCLUSION

Our results show that in FL both BMB and PET/CT should be considered at diagnosis, as their combined assessment provides independent prognostic value in the context of the most widely use clinical scores.

Plasma Concentrations and Cancer-Associated Mutations in Cell-Free Circulating DNA of Treatment-Naive Follicular Lymphoma for Improved Non-Invasive Diagnosis and Prognosis

Follicular lymphoma (FL) is the second most frequent non-Hodgkin lymphoma accounting for 10-20% of all lymphomas in western countries. As a clinically heterogeneous cancer, FL occasionally undergoes histological transformation to more aggressive B cell lymphoma types that are associated with poor prognosis. Here we evaluated the potential of circulating cell-free DNA (cfDNA) to improve the diagnosis and prognosis of follicular lymphoma patients. Twenty well-characterized FL cases (13 symptomatic and 7 asymptomatic) were prospectively included in this study. Plasma cfDNA, formalin-fixed paraffin-embedded (FFPE) tumor tissue DNA, and patient-matched granulocyte genomic DNA samples were obtained from 20 treatment-naive FL cases. Ultra-deep targeted next-generation sequencing was performed with these DNA samples by using a custom-designed platform including exons and exon-intron boundaries of 110 FL related genes. Using a strict computational bioinformatics pipeline, we identified 91 somatic variants in 31 genes in treatment-naive FL cases. Selected variants were cross-validated by using PCR-Sanger sequencing. We observed higher concentrations of cfDNA and a higher overlap of somatic variants present both in cfDNA and tumor tissue DNA in symptomatic FL cases compared to asymptomatic ones. Variants known to be associated with FL pathogenesis such as STAT6 p.D419 or EZH2 p.Y646 were observed in patient-matched cfDNA and tumor tissue samples. Consistent with previous observations, high Ki-67 staining, elevated LDH levels, FDG PET/CT positivity were associated with poor survival. High plasma cfDNA concentrations or the presence of BCL2 mutations in cfDNA showed significant association with poor survival in treatment-naive patients. BCL2 mutation evaluations in cfDNA improved the prognostic utility of previously established variables. In addition, we observed that a FL patient who had progressive disease contained histological transformation-associated gene (i.e. B2M and BTG1) mutations only in cfDNA. Pre-treatment concentrations and genotype of plasma cfDNA may be used as a liquid biopsy to improve diagnosis, risk stratification, and prediction of histological transformation. Targeted therapies related to oncogenic mutations may be applied based on cfDNA genotyping results. However, the results of this study need to be validated in a larger cohort of FL patients as the analyses conducted in this study have an exploratory nature.

Clinical application of [18F]FDG PET/CT in follicular lymphoma

The objective of the present paper was to review the clinical application of [¹⁸F]FDG PET/CT in follicular lymphoma (FL). Once it was clear that, despite it is characterized as indolent, this type of lymphoma usually shows a high [¹⁸F]FDG avidity, PET/CT became more important and it's now considered the standard technique in staging, re-staging and response evaluation. Many studies have shown its impact on the management of patients (as it can change the stage in a significant proportion of cases and lead to treatment modifications), its superiority over CT (mainly because it's able to distinguish fibrosis in residual masses from viable tumor) and its prognostic value. The latter was initially associated only to the degree of metabolic response, which has proved to be a strong and independent predictive factor in terms of disease-free survival (DFS) and overall survival (OS). Thus, a negative PET/CT scan could be considered a guarantee in high-tumor-burden follicular lymphoma patients. However, semiquantitative parameters such as metabolic tumor volume or total lesion glycolysis, may also provide useful information and help us to identify patients with poor prognosis, guiding a risk-adjusted management and follow-up.

Clinical outcomes with use of radiation therapy and risk of transformation in early-stage follicular lymphoma

Between 1998 and 2009, a total of 295 patients (median age 58, 53% females) with newly diagnosed early-stage follicular lymphoma (FL) were managed at Memorial Sloan Kettering Cancer Center. Approximately half of patients (137, 46%) underwent initial observation and half (158, 54%) immediate treatment: radiation alone (n = 108), systemic treatment alone (n = 29), or combined modality treatment (n = 21). Median follow-up was 8.4 years (range 0.3-17.2), and 10-year overall survival (OS) was 87.2%. OS was similar between initially-observed and immediately-treated patients (hazard ratio [HR]: 1.25, 95% CI: 0.67-2.36, p = 0.49). For patients receiving radiation alone, 5-year OS was 98.0%. Patients selected for systemic therapy alone had high-risk baseline features and had shorter OS than patients treated with radiation alone (HR 3.38, 95% CI 1.29-8.86, p = 0.01). Combined modality treatment did not yield superior survival compared with radiation alone (P > 0.05) but was associated with better progression-free survival (HR 0.36, 95% CI 0.14-0.90, p = 0.03). The rate of transformation increased steadily over time and was 4.2% at 5 years and 10.8% at 10 years. This modern-era analysis rationalized the role of initial observation in patients with early-stage FL although patients receiving radiation therapy also demonstrate excellent outcome.

Metabolic Biomarkers in B-Cell Lymphomas for Early Diagnosis and Prediction, as Well as Their Influence on Prognosis and Treatment

B-cell lymphomas exhibit a vast variety of clinical and histological characteristics that might complicate the diagnosis. Timely diagnosis is crucial, as treatments for aggressive subtypes are considered successful and frequently curative, whereas indolent B-cell lymphomas are incurable and often need several therapies. The purpose of this review is to explore the current advancements achieved in B-cell lymphomas metabolism and how these indicators help to early detect metabolic changes in B-cell lymphomas and the use of predictive biological markers in refractory or relapsed disease. Since the year 1920, the Warburg effect has been known as an integral part of metabolic reprogramming. Compared to normal cells, cancerous cells require more glucose. These cancer cells undergo aerobic glycolysis instead of oxidative phosphorylation to metabolize glucose and form lactate as an end product. With the help of these metabolic alterations, a novel biomass is generated by the formation of various precursors. An aggressive metabolic phenotype is an aerobic glycolysis that has the advantage of producing high-rate ATP and preparing the biomass for the amino acid, as well as fatty acid, synthesis needed for a rapid proliferation of cells, while aerobic glycolysis is commonly thought to be the dominant metabolism in cancer cells. Later on, many metabolic biomarkers, such as increased levels of lactate dehydrogenase (LDH), plasma lactate, and deficiency of thiamine in B-cell lymphoma patients, were discovered. Various kinds of molecules can be used as biomarkers, such as genes, proteins, or hormones, because they all refer to body health. Here, we focus only on significant metabolic biomarkers in B-cell lymphomas. In conclusion, many metabolic biomarkers have been shown to have clinical validity, but many others have not been subjected to extensive testing to demonstrate their clinical usefulness in B-cell lymphoma. Furthermore, they play an essential role in the discovery of new therapeutic targets.

Positron-emission tomography-based staging is cost-effective in early-stage follicular lymphoma

The objective was to assess the cost-effectiveness of staging PET/CT in early-stage follicular lymphoma (FL) from the Canadian health-care system perspective. Methods: The study population was FL patients staged as early-stage using conventional CT imaging and planned for curative-intent radiation therapy (RT). A decision analytic model simulated the management after adding staging PET/CT versus using staging CT alone. In the no-PET/CT strategy, all patients proceeded to curative-intent RT as planned. In the PET/CT strategy, PET/CT information could result in an increased RT volume, switching to a noncurative approach, or no change in RT treatment as planned. The subsequent disease course was described using a state-transition cohort model over a 30-y time horizon. Diagnostic characteristics, probabilities, utilities, and costs were derived from the literature. Baseline analysis was performed using quality-adjusted life years (QALYs), costs (2019 Canadian dollars), and the incremental cost-effectiveness ratio. Deterministic sensitivity analyses were conducted, evaluating net monetary benefit at a willingness-to-pay threshold of $100,000/QALY. Probabilistic sensitivity analysis using 10,000 simulations was performed. Costs and QALYs were discounted at a rate of 1.5%. Results: In the reference case scenario, staging PET/CT was the dominant strategy, resulting in an average lifetime cost saving of $3,165 and a gain of 0.32 QALYs. In deterministic sensitivity analyses, the PET/CT strategy remained the preferred strategy for all scenarios supported by available data. In probabilistic sensitivity analysis, the PET/CT strategy was strongly dominant in 77% of simulations (i.e., reduced cost and increased QALYs) and was cost-effective in 89% of simulations (i.e., either saved costs or had an incremental cost-effectiveness ratio below $100,000/QALY). Conclusion: Our analysis showed that the use of PET/CT to stage early-stage FL patients reduces cost and improves QALYs. Patients with early-stage FL should undergo PET/CT before curative-intent RT.

Positron emission tomography/computed tomography in the management of Hodgkin and B-cell non-Hodgkin lymphoma: An update

¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is now an integral part of lymphoma staging and management. Because of its greater accuracy compared with CT alone, PET/CT is currently routinely performed for staging and for response assessment at the end of treatment in the vast majority of FDG-avid lymphomas and is the cornerstone of response classification for these lymphomas according to the Lugano classification. Interim PET/CT, typically performed after 2 to 4 of 6 to 8 chemotherapy/chemoimmunotherapy cycles with or without radiation, is commonly performed for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-adapted or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics, such as the standardized uptake value, changes (Δ) in the standardized uptake value, metabolic tumor volume, and total lesion glycolysis, are being investigated as more reproducible and potentially more accurate predictors of response and prognosis. Despite the progress made in standardizing the use of PET/CT in lymphoma, challenges remain, particularly with respect to its limited positive predictive value, emphasizing the need for more specific molecular probes. This review highlights the most relevant applications of PET/CT in Hodgkin and B-cell non-Hodgkin lymphoma, its strengths and limitations, as well as recent efforts at implementing PET/CT-based metrics as promising tools for precision medicine.

Is it time for PET-guided therapy in follicular lymphoma

18F-fluorodeoxyglucose (FDG) Positron Emission Tomography-Computerised Tomography (PET) is now established as the gold-standard imaging modality for both staging and response assessment of follicular lymphoma (FL). In this Perspective, we propose where PET can, and cannot, guide clinicians in their therapeutic approach. PET at diagnosis/pre-treatment is important for staging, with greater sensitivity compared to standard CT and consequent improved outcomes in truly limited stage FL. Small datasets suggesting a high baseline SUVmax identifies de-novo histologic transformation (HT) are not corroborated by data from GALLIUM, the largest prospective study using modern therapies for FL. Nonetheless, the role of baseline quantitative PET measures requires further clarification. The median survival of patients with newly diagnosed FL is now potentially beyond 20 years. Treatment of symptomatic FL aims to achieve remission and optimise quality of life for as long as possible, with many patients achieving a "functional cure" at the cost of unwanted treatment effects. Several studies have identified that end-of-induction (EOI) PET after initial chemoimmunotherapy for patients with high tumour burden is strongly predictive of both progression-free and overall survival, and EOI PET is being evaluated as a platform for response-adapted treatment. There remain unmet needs: improving the inferior survival for patients remaining PET-positive; and quantifying the PFS and time to next treatment advantage, and additional toxicity of anti-CD20 maintenance in patients achieving complete metabolic remission. In the absence of an overall survival advantage for frontline maintenance, the question of using PET to guide our therapeutic approach is more important than ever in the context of the COVID-19 pandemic.

Radiotherapy for Non-Hodgkin Lymphomas

Radiotherapy (RT) plays a diverse and essential role in the contemporary management of non-Hodgkin lymphoma (NHL) and remains the single most powerful monotherapeutic intervention for both aggressive and indolent subtypes. Over the past decade, there have been significant advancements in radiation oncology practice, which have made modern treatments safer and more conformal. Despite this sophistication and evidence supporting a continued role for RT, numerous data suggest that utilization is on the decline. In this review, we discuss the rationale for RT in 4 commonly encountered scenarios: combined modality therapy for limited-stage aggressive NHL, consolidation therapy for advanced-stage aggressive NHL, and the changing roles of salvage RT for relapsed/refractory NHL in an era of new frontiers such as cellular therapies. We also evaluate current strategies to treat indolent histologies. We conclude with perspectives on how RT for the hematological malignancies may continue to evolve.

Abdominal and pelvic 18F-FDG PET/MR: a review of current and emerging oncologic applications

Positron emission tomography (PET) using fluorodeoxyglucose (¹⁸F-FDG) combined with magnetic resonance imaging (MR) is an emerging hybrid modality that has shown utility in evaluating abdominal and pelvic disease entities. Together, the high soft tissue contrast and metabolic/functional imaging capabilities make this modality ideal for oncologic imaging in many organ systems. Its clinical utility continues to evolve and future research will help solidify its role in oncologic imaging. In this manuscript, we aim to (1) provide an overview of the various PET/MR systems, describing the strengths and weaknesses of each system, and (2) review the oncologic applications for ¹⁸F-FDG PET/MR in the abdomen and pelvis.

Comparison of clinical and PET-derived prognostic factors in patients with non-Hodgkin lymphoma: a special emphasis on bone marrow involvement

OBJECTIVE

In patients with non-Hodgkin lymphoma (NHL), we investigated F FDG PET/computed tomography (CT) parameters, clinical findings, laboratory parameters, and bone marrow involvement (BMI) status for predictive methods in progression-free survival (PFS) and overall survival (OS), and whether F FDG PET/CT could take the place of bone marrow biopsy (BMB).

METHODS

The performance of F FDG PET/CT (BMPET) was evaluated. The prognostic value of maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), stage, international prognostic index (IPI) score, IPI risk, lactate dehydrogenase (LDH), B2 microglobulin, Ki67 proliferation index, and the presence of BMI was evaluated for OS and PFS. Kaplan-Meier curves were drawn for each designated cutoff value, and 5-year PFS and 7-year OS were evaluated using log-rank analysis.

RESULTS

The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of BMPET and BMB to identify BMI were 69, 100, 86.1, 80, 100%, and 81.6, 100, 92.5, 89, 100%, respectively. The sensitivity, specificity, PPV, NPV, and accuracy of BMPET in patients with Ki67- proliferation index >25% were all 100%. BMPET, IPI risk, MTV, and LDH were found to be independent prognostic predictors for PFS, whereas BMPET, SUVmax, and MTV for OS. Five-year PFS analysis estimated as follows: BMPET (+) = 22%, BMPET (-) = 80%, LDH ≤ 437 (U/L) = 86%, LDH > 437 (U/L) = 51%, MTV ≤ 56 (cm) = 87%, MTV > 56 (cm) = 49%, low IPI risk = 87%, intermediate IPI risk = 69%, high IPI risk = 25%. Seven-year OS analysis was found as: SUVmax ≤ 17.6 = 80%, SUVmax > 17.6 = 48%, MTV ≤ 56 (cm) = 84.4%, MTV > 56 (cm) = 45.8%, BMPET (-) = 72.5%, BMPET (+) = 42%.

CONCLUSION

In the Ki-67 proliferation index > 25% group, F FDG PET/CT was able to differentiate BMI independently from NHL subgroups. We recommend using this method with large patient groups. MTV and BMPET were independent prognostic indicators for OS and PFS and may help to determine high-risk patients.

Comparison of Bone Marrow Involvement with Bone Marrow Biopsy and PET-CT and Evaluation of Any Effects on Survival in Patients Diagnosed with Hodgkin and Non-Hodgkin Lymphoma

We aimed to demonstrate whether PET-CT can replace bone marrow biopsy in detecting bone marrow involvement in subtypes of lymphoma. In addition, we aimed to also reveal whether there is a difference between the mean survival of patients with bone marrow involvement via PET-CT or biopsy. A total of 276 newly diagnosed lymphoma patients who underwent bone marrow biopsy and PET-CT prior to the treatment were scanned retrospectively. Bone marrow biopsy was used as the standard method to investigate the presence of bone marrow involvement in PET-CT. The relationship between bone marrow involvement and mean survival was compared using both methods. Out of the 276 patients, bone marrow involvement was detected with PET-CT and with biopsy, respectively in 56 patients (20.2%) and in 78 patients (28.2%). In terms of PET-CT's accuracy with respect to revealing bone marrow involvement, the highest rates were achieved respectively in diffuse large B cell lymphoma (DLBCL) (87.4%) and Hodgkin lymphoma (HL) (77.7%). In both the PET-CT and bone marrow biopsy methods, Overall Survival (OS) was found to be significantly shorter in patients with involvement than in patients without involvement (P: 0.001). PET-CT may replace bone marrow (BM) biopsy in detecting the bone marrow involvement in aggressive lymphoma subtypes such as DLBCL and HL. The presence of BM involvement at the time of diagnosis in both PET-CT and BM biopsy is associated with poor prognosis, and OS is short in this group.

PET/CT vs CECT in assessment of therapeutic response in lymphoma

Background

Lymphoma incorporates histologically variable cancers derived from the immune system cells. The distinctive feature of lymphoma is the rapid increase in size and number of lymph nodes and/or secondary lymphoid tissues.

The aim of the work is to evaluate the accuracy of PET/CT vs CECT in the assessment of response to therapy in lymphoma patients: both early and late therapeutic response assessment.

This retrospective study was conducted on 80 patients with different types of lymphoma recruited and enrolled from a university hospital. All 80 patients underwent pre-treatment, during the course of chemotherapy and at the end of planned treatment contrast-enhanced СT (СEСT) and PET-СT. Interpretation of the СEСT and the fusion images PET/СT each was done separately and comparison of the results was achieved.

Results

PET/CT and contrast-enhanced computed tomography were concurrent in results in 55% of cases during treatment and 75% at the end of treatment with CT sensitivity of 61.1%, specificity of 92.2%, and accuracy of 76.2% during treatment in comparison to 100% sensitivity and specificity of PET/CT. Sensitivity of CT at end of treatment was 57.5%, specificity 86.7%, and accuracy 71.6% as compared to 100% sensitivity and specificity of PET/CT.

Conclusion

PET/СT using 2-deoxy-2-[18F] fluoro-d-glucose is considered one of the best oncologic imaging modalities at the time being with valuable applications in lymphoma. It is very efficient with least possible pitfalls and false results compared to either of its components alone and to side by side reading of separately acquired PET and СT. PET/CT can detect both anatomical information as well as metabolical information providing more data and thus giving more accurate results than CECT. It is becoming а standard modality for lymphoma providing а new vision to management and treatment plan.

Stage-specific trends in primary therapy and survival in follicular lymphoma: a nationwide population-based analysis in the Netherlands, 1989-2016

We assessed stage-specific trends in primary therapy and relative survival among adult follicular lymphoma (FL) patients diagnosed in the Netherlands between 1989-2016 (N = 12,372; median age, 62 years; and 21% stage I disease). Patients were stratified by disease stage and subsequently categorized into four calendar periods (1989-1995, 1996-2002, 2003-2008, and 2009-2016) and three age groups (18-60, 61-70, and >70 years). The use of radiotherapy in stage I FL remained relatively stable over time and across the three age groups (i.e., 66%, 54%, and 49% in 2009-2016, respectively). In stage II-IV FL, the start of chemotherapy within 12 months post-diagnosis decreased over time, indicating a broader application of a watch-and-wait approach. Relative survival improved considerably over time, especially since 2003 when rituximab was introduced in the Netherlands, and for stage III-IV FL patients and older age groups. Five-year relative survival for patients with stage I-II versus stage III-IV FL in the period 2009-2016 was 96% versus 90%, 93% versus 83%, and 92% versus 68% across the three age groups, respectively. Collectively, the improvement in survival since 2003 is accounted for by advances in FL management, particularly the implementation of rituximab. There remains, however, room for improvement among elderly stage III-IV FL patients.

Fluorodeoxyglucose-Positron Emission Tomography Predicts Bone Marrow Involvement in the Staging of Follicular Lymphoma

BACKGROUND

Standard bone marrow biopsy (BMB) and bone involvement with follicular lymphoma (FL) on positron emission tomography (PET)/computed tomography (CT) both predict early clinical failure in FL. The key clinical question is whether PET/CT findings can obviate the need for BMB. The goal of this study was to determine the value of PET/CT in determining bone involvement in FL, using posterior iliac crest BMB as the gold standard.

MATERIALS AND METHODS

A total of 548 patients with newly diagnosed grade 1-3A FL were included. The presence, pattern, and location of bone involvement, spleen involvement, and standardized uptake values (SUVs) in the L3 vertebral body were recorded for all patients and compared with the BMB report.

RESULTS

Excluding patients with focal bone lesions on PET/CT, the sensitivity and specificity of PET/CT in detecting bone or marrow involvement, compared with BMB, were 53% and 88%, respectively. The sensitivity and specificity of spleen involvement on PET/CT in predicting a positive BMB were 55% and 86%, respectively. An L3 SUVmax of less than 2.0 resulted in a negative predictive value (NPV) of 96% for marrow involvement on BMB; an L3 SUVmean below 1.4 resulted in an NPV of 100%.

CONCLUSION

In newly diagnosed FL, PET/CT-detected bone and splenic involvement is highly specific for a positive BMB, and very low SUV values (<2.0 SUVmax and < 1.4 SUVmean ) in the lumbar spine have a high NPV for a negative BMB. Routine BMB may be obviated in these patients. BMB remains necessary to definitively exclude bone marrow involvement in a large majority of patients with a negative PET.

IMPLICATIONS FOR PRACTICE

Predicting early clinical failure in follicular lymphoma (FL) is important but difficult. Bone marrow involvement by FL is associated with early clinical failure, and determining this involvement is a key component of the initial staging. This study highlights that in certain patients, positron emission tomography/computed tomography is sufficient in determining bone or marrow involvement, without the need for a confirmatory bone marrow biopsy (BMB). An algorithm is provided based on these findings to help clinicians determine which patients would benefit from BMB and when it can be avoided.

Positron-emission tomography-based staging reduces the prognostic impact of early disease progression in patients with follicular lymphoma

BACKGROUND

Previous studies reported that early progression of disease (POD) after initial therapy predicted poor overall survival (OS) in patients with follicular lymphoma (FL). Here, we investigated whether pre-treatment imaging modality had an impact on prognostic significance of POD.

METHODS

In this retrospective study, we identified 1088 patients with grade I-IIIA FL; of whom, 238 patients with stage II-IV disease were initially treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), and 346 patients were treated with rituximab-based chemotherapy. Patients (N = 484) from the FOLL05 study served as an independent validation cohort. We risk-stratified patients based on pre-treatment radiographic imaging (positron-emission tomography [PET] versus computed tomography [CT]) and early POD status using event-defining and landmark analyses. A competing risk analysis evaluated the association between early POD and histologic transformation.

RESULTS

In the discovery cohort, patients with POD within 24 months (PFS24) of initiating R-CHOP therapy had a 5-year OS of 57.6% for CT-staged patients compared with 70.6% for PET-staged patients. In the validation cohort, the 5-year OS for patients with early POD was 53.9% and 100% in CT- and PET-staged patients, respectively. The risk of histologic transformation in patients whose disease progressed within one year of initiating therapy was higher in CT-staged patients than in PET-staged patients (16.7% versus 6.3%, respectively), which was associated with a 9.7-fold higher risk of death.

CONCLUSION

In FL, pre-treatment PET staging reduced the prognostic impact of early POD compared with CT staging. Patients with early POD and no histologic transformation have an extended OS with standard therapy.

Pre-treatment maximum standardized uptake value predicts outcome after frontline therapy in patients with advanced stage follicular lymphoma

The impact of pre-treatment maximum standardized uptake value (SUV_max) on the outcome of follicular lymphoma (FL) following specific frontline regimens has not been explored. We performed a retrospective analysis of 346 patients with advanced stage follicular lymphoma (FL) without histological evidence of transformation, and analyzed the impact of SUV_max on outcome after frontline therapy. Fifty-two (15%) patients had a SUV_max >18, and a large lymph node ≥6 cm was the only factor associating with SUV_max >18 on multivariate analysis (odds ratio 2.7, 95% confidence interval [CI]: 1.3-5.3, P=0.006). The complete response rate was significantly lower among patients treated with non-anthracycline-based regimens if SUV_max was >18 (45% vs. 92%, P<0.001), but not among patients treated with R-CHOP (P=1). SUV_max >18 was associated with significantly shorter progression-free survival among patients treated with non-anthracycline-based regimens (77 months vs. not reached, P=0.02), but not among patients treated with R-CHOP (P=0.73). SUV_max >18 associated with shorter overall survival (OS) both in patients treated with R-CHOP (8-year OS 70% vs. 90%, P=0.02) and non-anthracycline-based frontline regimens (8-year OS 50% vs. 85%, P=0.001). In conclusion, pre-treatment PET scan has prognostic and predictive value in patients with advanced stage FL receiving frontline treatment.

Whole-body magnetic resonance imaging in paediatric Hodgkin lymphoma - evaluation of quantitative magnetic resonance metrics for nodal staging

BACKGROUND

Whole-body MRI is used for staging paediatric Hodgkin lymphoma, commonly using size thresholds, which fail to detect disease in normal-size lymph nodes.

OBJECTIVE

To investigate quantitative whole-body MRI metrics for nodal characterisation.

MATERIALS AND METHODS

Thirty-seven children with Hodgkin lymphoma underwent 1.5-tesla (T) whole-body MRI using short tau inversion recovery (STIR) half-Fourier-acquisition single-shot turbo-spin-echo and diffusion-weighted imaging (DWI). 18Flourine-2-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET)/CT was acquired as the reference standard. Two independent readers assessed 11 nodal sites. The readers measured short-axis-diameter, apparent diffusion coefficient, (ADC) and normalised T2-signal intensity of the largest lymph node at each site. We used receiver operating characteristics (ROC)/area-under-the-curve (AUC) analysis for each MRI metric and derived sensitivity and specificity for nodes with short-axis diameter ≥10 mm. Sub-analysis of sensitivity and specificity was performed with application of ADC cut-off values (<0.77, <1.15 and <1.79×10-3 mm2 s-1) to 5- to 9-mm nodes.

RESULTS

ROC/AUC values for reader 1/reader 2 were 0.80/0.80 and 0.81/0.81 for short-axis-diameter measured using DWI and STIR half-Fourier-acquisition single-shot turbo spin echo, respectively; 0.67/0.72 for normalised T2 signal intensity and 0.74/0.67 for ADC. Sensitivity and specificity for a short-axis diameter ≥10 mm were 84.2% and 66.7% for Reader 1 and 82.9% and 68.9% for Reader 2. Applying a short-axis-diameter ≥10-mm threshold followed by ADC cut-offs to normal-size 5- to 9-mm nodes resulted in sensitivity and specificity for Reader 1 of 88.8% and 60%, 92.1% and 56.7%, and 100% and 16.7%; and for Reader 2, 86.1% and 67.2%, 95.3% and 65.6%, and 100% and 19.7%; and ADC thresholds of <0.77, <1.15, and <1.79×10-3 mm2 s-1, respectively.

CONCLUSION

Nodal size measurement provides the best single classifier for nodal disease status in paediatric Hodgkin lymphoma. Combined short-axis diameter and ADC thresholds marginally improve sensitivity and drop specificity compared with size classification alone.

Predictive Value of Interim and End-of-Therapy 18F-FDG PET/CT in Patients with Follicular Lymphoma

PURPOSE

18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is the standard imaging modality for response evaluation in FDG-avid lymphoma, but the prognostic value is not established in follicular lymphoma (FL). This study investigated the prognostic value of Deauville 5-point scale (D5PS) from paired interim PET/CT (PETInterim) and end-of-induction therapy PET/CT (PETEOI) in patients with FL.

METHODS

FL staging and response assessment PET/CT images from 2013 to 2015 were retrospectively reviewed. PETInterim was performed 3 or 4 cycles after chemotherapy and PETEOI after 6 or 8 cycles. D5PS scores of 1, 2, and 3 were considered as negative (-), and scores 4 and 5 were considered as positive (+). Statistical analysis was done using Cox regression analysis, Kaplan-Meier survival analysis, and the log-rank test.

RESULTS

Thirty-three patients with set of baseline, interim, and end-of-induction therapy PET/CT studies were included. Ten patients (30.3%) had progression. The median progression-free survival (PFS) was 38.8 months (range 3.5-72.7 months). On PETInterim, 23 patients were negative and 10 were positive. On PETEOI scans, 29 patients were negative, and 4 were positive. On multivariate analysis, PETEOI(-) was associated with longer PFS. PETInterim(+) and PETEOI(+) patients had a significantly shorter PFS than PETInterim(-) patients (39.9 months, 95% confidence interval [CI] 23.0-56.9, versus 55.5 months, 95% CI 49.7-61.2, p = 0.005) and PETEOI(-) patients (14.2 months, 95% CI 8.5-19.8, versus 60.5 months, 95% CI 52.1-69.0, p < 0.001).

CONCLUSION

For patients with FL, PETInterim and PETEOI response is predictive of PFS, and PETEOI(+) is an independent prognostic factor for progression of FL.

Uptake of [18F]fluorodeoxyglucose in initial positron-emission tomography predicts survival in MALT lymphoma

The role of [¹⁸F]fluorodeoxyglucose (FDG) positron-emission tomography (PET) in mucosa-associated lymphoid tissue (MALT) of marginal zone lymphoma remains poorly defined. We correlated initial PET with pathology, clinical factors, and outcome. From January 2001 to July 2012, 173 MALT lymphoma patients with a biopsied lesion identified on PET within 90 days of tissue biopsy were analyzed. PET positivity and intensity of FDG uptake were correlated with clinical factors and patient outcome. Among 173 accrued cases, biopsied site was PET avid in 123 patients (71%); median standardized uptake value (SUV) was 6.0 (range: 0.7-28.0), and SUV >10.0 in 20 patients (16%). PET avidity varied by organ sites. PET positivity correlated with higher International Prognostic Index, but not with 5-year overall survival (OS; 96% vs 88%, PET negative vs positive, P = .229) or 5-year progression-free survival (67% vs 56%, P = .493). SUV was an independent prognostic factor of OS, and an increased SUV was associated with a decreasing 5-year OS. Patients who presented with SUV ≥10 had a higher rate of subsequent large cell transformation (20% vs 5%, P = .035) and inferior OS (78% vs 92%, P = .008). The exact role of FDG PET in the management of MALT lymphoma, beyond initial staging, remains to be defined.

Definitive radiotherapy for localized follicular lymphoma staged by 18F-FDG PET-CT: a collaborative study by ILROG

Radiotherapy (RT) can be curative in patients with localized follicular lymphoma (FL), with historical series showing a 10-year disease-free survival of 40 to 50%. As ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography with computerized tomography (PET-CT) upstages 10 to 60% of patients compared to CT, we sought to evaluate outcomes in patients staged by PET-CT, to determine if more accurate staging leads to better patient selection and results. We conducted a multicenter retrospective study under the direction of the International Lymphoma Radiation Oncology Group (ILROG). Inclusion criteria were: RT alone for untreated stage I to II FL (grade 1-3A) with dose equivalent ≥24 Gy, staged by PET-CT, age ≥18 years, and follow-up ≥3 months. End points were freedom from progression (FFP), local control, and overall survival (OS). A total of 512 patients treated between 2000 and 2017 at 16 centers were eligible for analysis; median age was 58 years (range, 20-90); 410 patients (80.1%) had stage I disease; median RT dose was 30 Gy (24-52); and median follow-up was 52 months (3.2-174.6). Five-year FFP and OS were 68.9% and 95.7%. For stage I, FFP was 74.1% vs 49.1% for stage II (P < .0001). Eight patients relapsed in-field (1.6%). Four had marginal recurrences (0.8%) resulting in local control rate of 97.6%. On multivariable analysis, stage II (hazard ratio [HR], 2.11; 95% confidence interval [CI], 1.44-3.10) and BCL2 expression (HR, 1.62; 95% CI, 1.07-2.47) were significantly associated with less favorable FFP. Outcome after RT in PET-CT staged patients appears to be better than in earlier series, particularly in stage I disease, suggesting that the curative potential of RT for truly localized FL has been underestimated.

Application of Quantitative Indexes of FDG PET to Treatment Response Evaluation in Indolent Lymphoma

Purpose

Although ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a standard imaging modality for response evaluation in FDG-avid lymphoma, there is a controversy using FDG PET in indolent lymphoma. The purpose of this study was to investigate the effectiveness of quantitative indexes on FDG PET in response evaluation of the indolent lymphoma.

Methods

Fifty-seven indolent lymphoma patients who completed chemotherapy were retrospectively enrolled. FDG PET/computed tomography (CT) scans were performed at baseline, interim, and end of treatment (EOT). Response was determined by Lugano classification, and progression-free survival (PFS) by follow-up data. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured in the single hottest lesion (target A) or five hottest lesions (target B). Their efficacies regarding response evaluation and PFS prediction were evaluated.

Results

On EOT PET, SUV_max, and MTV of both targets were well associated with visual analysis. Changes between initial and EOT PET were not significantly different between CR and non-CR groups. On interim PET, SUV_max, and %ΔSUV_max in both targets were significantly different between CR and non-CR groups. For prediction of PFS, most tested indexes were significant on EOT and interim PET, with SUV_max being the most significant prognostic factor.

Conclusion

Quantitative indexes of FDG PET are well associated with Lugano classification in indolent lymphoma. SUV_max measured in the single hottest lesion can be effective in response evaluation and prognosis prediction on interim and EOT PET.

Current and future therapeutic approaches for the treatment of follicular lymphoma

INTRODUCTION

Recent advances in prognostication as well as management of Follicular Lymphoma (FL) are moving to personalized approach. Areas covered: Prognostic scores as well as consolidated and innovative therapeutic approaches are evaluated according to the various presentation modalities. For asymptomatic, low-tumor burden FL, a 'watch and wait' policy is currently the first-choice approach, although possible alternatives are discussed. Early stage FL may be treated with local radiotherapy although the role of minimal residual disease in possible additional agents should be determined. The first line treatment for symptomatic FL is chemo-immunotherapy followed by two years maintenance therapy with anti-CD20 monoclonal antibodies. A deeper knowledge of FL biology has opened new perspectives regarding the timing of therapy and has offered new targets for the development of novel agents that aim to change the therapeutic scenario of FL management. Expert commentary: The introduction of novel agents could question the incurability of FL and change the therapeutic goal from prolonging the complete remission state to eradicating the disease in young/fit patients, as well as improving quality of life in elderly/unfit patients. In the near future, combining new biologic agents and adoptive cell therapies could help in achieving these aims.

Use of FDG PET/CT in identification of bone marrow involvement in diffuse large B cell lymphoma and follicular lymphoma: comparison with iliac crest bone marrow biopsy

Background Non-Hodgkin's lymphoma (NHL) accounts for around 4% of new cancer cases annually. Bone marrow involvement is important for staging and management. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) is used increasingly to identify this, in addition to bone marrow biopsy (BMB), which is seen as "gold" reference standard. Purpose To compare determination of bone marrow involvement by FDG PET/CT against BMB in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). Material and Methods This was a retrospective study of patients with histologically confirmed NHL at a single UK cancer center undergoing pre-treatment FDG PET/CT and BMB between June 2010 and February 2013. Information was collected from patient notes, cancer registry, histological and imaging reports. Diagnostic accuracy of FDG PET/CT was determined, compared to BMB as the reference standard. Results Twenty-four patients with DLBCL and 12 with FL were included. Five DLBCL patients had bone marrow involvement on PET/CT; all were confirmed on BMB. Three FL patients had marrow involvement on PET/CT but not on BMB; one FL patient had positive BMB but negative PET/CT. Using BMB as the reference standard, the sensitivity and specificity of FDG PET/CT for detecting bone marrow involvement in DLBCL were 100% and 100%, respectively, and in FL were 0% and 72.7%, respectively. Conclusion FDG PET/CT is accurate for detection of bone marrow involvement in newly diagnosed DLBCL, but not FL. In DLBCL, positive FDG PET/CT may negate the need for routine BMB, although BMB in addition or combination may be appropriate if this would influence management or prognosis.

Current prognostic and predictive factors in follicular lymphoma

Follicular lymphoma (FL) is generally considered an indolent disorder. With modern day treatments, long remissions are often achieved both in the front-line and relapsed setting. However, a subset of patients has a more aggressive course and a worse outcome. Their identification is the main purpose of modern day prognostic tools. In this review, we attempt to summarize the evidence concerning prognostic and predictive factors in FL, including (1) pre-treatment factors, from baseline clinical characteristics and imaging tests to histological grade, the microenvironment and genomic abnormalities; (2) post-treatment factors, i.e., depth of response, measured both by imaging tests and minimal residual disease; (3) factors at relapse and duration of response; and (4) prognostic factors in histological transformation. We conclude that, despite the existence of numerous tools, the availability of some of them is still limited; they generally suffer from notable downsides, and most have unproven predictive value, thus having scarce bearing on the choice of regimen at present. However, with the technological and scientific developments of the last few years, the potential for these prognostic factors is promising, particularly in combination, which will probably, in time, help guide therapeutic decisions.

Treatment and prognosis of stage I follicular lymphoma in the modern era - does PET matter?

Follicular lymphoma (FL) is the most common subtype of indolent non-Hodgkin lymphoma. Patients with stage I disease are usually treated with radiotherapy (RT). In previous studies, mostly from the pre positron emission tomography-computed tomography (PET-CT) era, the 5 year progression-free survival (PFS) and overall survival (OS) rates of stage I disease were 60-80% and 80-93%, respectively. This study retrospectively evaluated the outcome of stage I FL which was treated with involved field RT in the PET-CT era between 2002 and 2015. Ninety-one patients were enrolled. Five year PFS and OS rates were 73% and 97%, respectively. Relapse occurred in 19 (21%) patients, 74% occurring outside the radiation field. In conclusion, PET-CT staging of clinical stage I FL may contribute to the improved prognosis in patients treated with RT compared to historical cohorts, possibly due to better identification of "genuine" stage I disease.

PET-CT in Staging, Response Evaluation, and Surveillance of Lymphoma

OPINION STATEMENT

Lymphoma represents a broad spectrum of diseases with diverse biology, clinical behavior, and imaging features. Functional imaging with 18-F-fluorodeoxyglucose (FDG)-positron emission tomography combined with computed tomography (PET-CT) is widely recognized as the most sensitive and specific imaging modality for patients with lymphoma and is used as part of staging, response evaluation, and surveillance in patients with Hodgkin (HL) and non-Hodgkin lymphoma (NHL). Recent efforts at standardizing the conduct and consensus interpretation of PET-CT have facilitated its use in patients on clinical studies and beyond. The role of PET-CT has been affirmed in some clinical situations, such as staging and end-of-treatment evaluation in Hodgkin lymphoma and diffuse large B cell lymphoma (DLBCL), and in the evaluation of aggressive transformation of an indolent lymphoma. However, the role of functional imaging in other histologies and clinical settings is not as clear given the higher rate of false positive results and the costs inherent to PET-CT. There is little evidence to suggest its utility or impact on outcome in most indolent lymphomas, or in the setting of post-treatment surveillance. In addition, there remains controversy about the value of PET-CT in early response assessment during active therapy, particularly in DLBCL. This review will evaluate the evidence surrounding the role of PET-CT in staging, response evaluation and surveillance of Hodgkin and non-Hodgkin lymphoma.

18F-FDG PET/CT in the clinical management of patients with lymphoma

The aim of this work was to review the current recommendations for staging and response assessment of patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) in routine clinical practice after chemotherapy and/or stem cell transplantation. A five-point scale (5-PS) from the First International Workshop on PET in Lymphoma in Deauville, France, in 2009, was recommended as the standard tool to score imaging to assess treatment response in patients with lymphoma using ¹⁸F-Fluorodeoxyglucose (FDG) PET/CT. Following the recommendations of the 11th and 12th International Conferences on Malignant Lymphoma held in Lugano (Switzerland), in 2011 and 2013, respectively, a consensus (the so-called Lugano Classification) was reached regarding the use of PET/CT for staging and response assessment in FDG-avid lymphomas. As a result, ¹⁸F-FDG PET/CT was formally incorporated into standard staging for FDG-avid lymphomas. A bone marrow biopsy is no longer indicated for the routine staging of HL and most diffuse large B-cell lymphomas. PET/CT will be used to assess response in FDG-avid histologies using the 5-point scale. The recent introduction of biological agents with immune mechanisms requires flexibility in interpretations of the Lugano criteria due to tumour flare or a pseudo-progression effect produced by these agents. Provisional criteria have been proposed (Lymphoma Response to Immunomodulatory Therapy Criteria) with the introduction of the term 'Indeterminate Response' in order to identify this phenomenon until confirmed as flare/pseudoprogression or true progression. All these recommendations will improve evaluations of patients with lymphoma, and allow comparison of results from clinical practice and trials.

FDG-PET Scan: a new Paradigm for Follicular Lymphoma Management

In the present review, the reader will be led to the most relevant observations that prompted oncologists and haematologist to consider FDG-PET/CT as a new paradigm for FL management in clinical practice. The role of functional imaging in lymphoma staging, restaging, prognostication, and metabolic tumour volume computing will be reviewed in detail. Moreover, a special focus will be addressed to technical and practical aspects of PET scan reporting, which have been set during the last decade to ensure the reproducibility of the therapeutic results. Finally, the predictive role of PET/CT on long-term treatment outcome will be compared with another well-known prognosticator as minimal residual disease (MRD) detection by Immunoglobulin gene rearrangement assessment.

[18 F]-FDG PET/CT in the staging and management of indolent lymphoma: A prospective multicenter PET registry study

BACKGROUND

To measure the clinical impact of pretreatment fludeoxyglucose positron emission tomography/computed tomography (PET/CT) on the staging and management of apparent limited stage indolent lymphoma being considered for curative radiation therapy.

METHODS

We conducted a prospective multicenter registry study that included 197 patients accrued between May 1, 2012, and December 31, 2015. Pre-PET/CT stage, determined by clinical and CT data, was documented. If pre-PET/CT stage was indeterminate, a stage was assigned to the patient by the referring oncologist according to best clinical judgment and treatment intent. After PET/CT, revised stage and planned management were recorded and compared with data on actual treatment received available through provincial databases (n = 155).

RESULTS

PET/CT resulted in the upstaging of 47 (23.9%) patients with presumed limited stage disease (stage I-II) to advanced stage disease (stage III-IV) (P < .0001). Ten (5.1%) patients were downstaged by PET/CT, 4 of whom migrated from advanced to limited stage disease. Twenty-eight (14.2%) patients with a specific pre-PET/CT stage had equivocal PET/CT findings that required further evaluation to confirm disease extent. After PET/CT, 95 (61.3%) patients were planned to receive active treatment. Of the 59 patients planned for radiotherapy alone post-PET/CT, 34 (57.6%) received this treatment (P = .002), and nearly 80% of them (n = 27) had confirmed limited stage disease.

CONCLUSION

PET/CT has a significant impact on staging and management in patients with apparent limited stage indolent lymphoma who are being considered for curative radiotherapy. PET/CT should be routinely incorporated into the workup of these patients. Cancer 2017;123:2860-66. © 2017 American Cancer Society.

Systematic Review on the Additional Value of 18F-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography in Staging Follicular Lymphoma

PURPOSE

This study aimed to systematically review the additional value of F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) to computed tomography (CT) for staging newly diagnosed follicular lymphoma in terms of Ann Arbor staging and Follicular Lymphoma International Prognostic Index (FLIPI) risk stratification.

MATERIALS AND METHODS

The PubMed/MEDLINE database was searched for relevant original studies. Included studies were methodologically assessed. Data on the frequency of FDG-PET-induced changes in Ann Arbor stage and FLIPI score relative to CT were (meta-)analyzed when possible.

RESULTS

Seven studies with a total of 349 patients were included. Overall, studies were of very poor methodological quality, with lack of histological verification of additionally detected lesions at FDG-PET in almost all cases and only 1 study that exclusively included patients with CT-based limited nonbulky stage I to II disease. The proportion of patients who were upstaged by FDG-PET compared with CT ranged from 0.0% to 45.2%, with a pooled summary proportion of 18.7% (95% confidence interval, 10.8%-30.4%). The single study that only included patients with CT-based limited nonbulky stage I to II disease reported FDG-PET-induced upstaging in 40.5% (95% confidence interval, 27.0%-55.5%) of cases. No study reported data on the influence of FDG-PET on FLIPI risk stratification.

CONCLUSIONS

Although upstaging by FDG-PET compared with CT occurs in a considerable proportion of patients, the available studies on this topic have numerous methodological errors. Data on FDG-PET-induced FLIPI risk stratification changes relative to CT are lacking. Future well-designed studies are needed before FDG-PET can be recommended for routine pretreatment staging of follicular lymphoma.

Is There a Role for Minimal Residual Disease Monitoring in Follicular Lymphoma in the Chemo-Immunotherapy Era?

After 25 years, evaluation of minimal residual disease (MRD) in follicular lymphoma (FL) has become a standardized technique frequently integrated into clinical trials for its consistent and independent prognostic significance. Achievement of a sustained MRD negativity is a marker of treatment sensibility that has been associated with excellent clinical outcome in terms of clinical response and progression-free survival, independently from the employed therapy. However, no survival advantages has been reported for MRD negative patients and despite the compelling results of clinical trials, MRD evaluation has currently no role in clinical practice. Ongoing clinical trials will help in clarifying the potential setting in which MRD monitoring may have a routine clinical application i.e. allowing de-escalation of standard maintenance therapy in very low risk patients. In this review the clinical implications of MRD monitoring in Rituximab-era are discussed in light of the current treatment paradigms most aimed at reducing toxicities, and the response definition that now routinely integrates PET scan.

Advancing Precision Nuclear Medicine and Molecular Imaging for Lymphoma

PET with fluorodeoxyglucose F 18 (¹⁸F FDG-PET) is a meaningful biomarker for the detection, targeted biopsy, and treatment of lymphoma. This article reviews the evolution of ¹⁸F FDG-PET as a putative biomarker for lymphoma and addresses the current capabilities, challenges, and opportunities to enable precision medicine practices for lymphoma. Precision nuclear medicine is driven by new imaging technologies and methodologies to more accurately detect malignant disease. Although quantitative assessment of response is limited, such technologies will enable a more precise metabolic mapping with much higher definition image detail and thus may make it a robust and valid quantitative response assessment methodology.

[18F] Positron emission tomography response after rituximab-containing induction therapy in follicular lymphoma is an independent predictor of survival after adjustment for FLIPI in academic and community-based practice

Positron emission tomography (PET) after induction therapy in follicular lymphoma (FL) is predictive of survival in clinical trials. We describe use of PET and computed tomography (CT) after rituximab-based induction therapy in FL patients followed by the National LymphoCare Study and explore the association between imaging response assessment and survival. Among 1289 patients, imaging consisted of: PET ± CT (35%), CT alone (42%), other/no imaging (24%). Median follow-up was 7.6 years. In unadjusted analyses, positive PET ± CT and CT were prognostic of inferior OS (HR 1.78; 95% CI: 1.16-2.72 and HR 1.61, 95% CI: 1.13-2.29, respectively) and PFS (HR 1.63, 95% CI: 1.21-2.20 and HR 1.45, 95% CI: 1.12-1.89, respectively). Adjusting for FL International Prognostic Index, PET remained predictive of OS (HR 1.54, 95% CI: 1.01-2.36) and PFS (HR 1.54, 95% CI: 1.14-2.07). Residual disease via PET in FL is prognostic of survival in clinical practice.