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

How [18F]FDG-PET/CT Affects the Management of Patients with Differentiated Thyroid Carcinoma in Clinical Routines

PURPOSE

To investigate the impact of [18F]FDG-PET/CT on the management of differentiated thyroid carcinoma (DTC) in routine clinical settings.

MATERIAL AND METHODS

In total, 98 patients (55 females, age 56 ± 18 years) with histologically confirmed thyroid cancer, including all types of DTC and poorly differentiated thyroid cancer (PDTC, n = 7), underwent [18F]FDG-PET/CT for staging or recurrence diagnostics performed using a state-of-the art clinical scanner (Biograph mCT, Siemens Healthineers) with a standardized examination protocol. The impact of PET/CT on clinical decision making was prospectively evaluated using standardized questionnaires completed by the referring physicians before and after PET/CT. Patient outcome was analyzed for OS drawn from patient records.

RESULTS

Referring physicians were unable to establish a treatment plan for 81% of patients with thyroid cancer in the absence of PET/CT. The use of PET/CT had a notable influence on patient management, leading to the development of a well-defined treatment plan for 92% of patients. Moreover, after PET/CT a change in pre-PET/CT-intended treatments occurred in 32% of cases, and further invasive diagnostic could be waived in 7% of cases. [18F]FDG-PET/CT revealed a tumor detection rate of 68% (local tumor: 19%, lymph node metastases: 40%, distant metastases: 42%). HTg levels, when stimulated via TSH, were considerably higher in patients with metastases detected on PET/CT, compared to those without metastatic findings (p = 0.02). OS was significantly worse in patients with PDTC (p = 0.002) compared to follicular thyroid cancer (FTC) and PTC or even in patients with distant metastases at first diagnosis (p = 0.03).

CONCLUSIONS

This prospective registry study confirms that [18F]FDG-PET/CT used in a routine clinical setting has a very important impact on the management of patients with thyroid cancer by initiating treatments and reducing the uses of additional imaging and invasive tests.

Follicular lymphoma: an update on biology and optimal therapy

Follicular lymphoma (FL) is a mature B-cell neoplasm with a mostly indolent course. Genetic hallmark characteristics are Bcl-2 overexpression based on a t(14;18) translocation and additional secondary genetic and epigenetic aberrations. Standard treatment for early-stage patients has curative intent and usually consists of radiotherapy with or without rituximab. In the advanced stage, the main therapeutic focus is on prolonged remissions. Therefore, treatment in asymptomatic patients is usually deferred. Symptomatic patients are subject to immunochemotherapy induction followed by antibody maintenance. Importantly, about one in five patients subsequently experiences a more rapid clinical course, achieving only short remissions with multiple relapses (POD24). In those patients, there is still an urgent need for improved therapeutic options. Accordingly, a plethora of targeted and immunotherapeutic options, including immunomodulatory drugs, small molecule inhibitors, monoclonal antibodies as well as bispecific T-cell engager antibodies and CAR-T cell products have been recently evaluated in such relapsed high-risk patients.

Genomic and microenvironmental landscape of stage I follicular lymphoma, compared with stage III/IV

Although the genomic and immune microenvironmental landscape of follicular lymphoma (FL) has been extensively investigated, little is known about the potential biological differences between stage I and stage III/IV disease. Using next-generation sequencing and immunohistochemistry, 82 FL nodal stage I cases were analyzed and compared with 139 FL stage III/IV nodal cases. Many similarities in mutations, chromosomal copy number aberrations, and microenvironmental cell populations were detected. However, there were also significant differences in microenvironmental and genomic features. CD8+ T cells (P = .02) and STAT6 mutations (false discovery rate [FDR] <0.001) were more frequent in stage I FL. In contrast, programmed cell death protein 1-positive T cells, CD68+/CD163+ macrophages (P < .001), BCL2 translocation (BCL2trl+) (P < .0001), and KMT2D (FDR = 0.003) and CREBBP (FDR = 0.04) mutations were found more frequently in stage III/IV FL. Using clustering, we identified 3 clusters within stage I, and 2 clusters within stage III/IV. The BLC2trl+ stage I cluster was comparable to the BCL2trl+ cluster in stage III/IV. The two BCL2trl- stage I clusters were unique for stage I. One was enriched for CREBBP (95%) and STAT6 (64%) mutations, without BLC6 translocation (BCL6trl), whereas the BCL2trl- stage III/IV cluster contained BCL6trl (64%) with fewer CREBBP (45%) and STAT6 (9%) mutations. The other BCL2trl- stage I cluster was relatively heterogeneous with more copy number aberrations and linker histone mutations. This exploratory study shows that stage I FL is genetically heterogeneous with different underlying oncogenic pathways. Stage I FL BCL2trl- is likely STAT6 driven, whereas BCL2trl- stage III/IV appears to be more BCL6trl driven.

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.

Translating a radiolabeled imaging agent to the clinic

Molecular Imaging is entering the most fruitful, exciting period in its history with many new agents under development, and several reaching the clinic in recent years. While it is unusual for just one laboratory to take an agent from initial discovery through to full clinical approval the steps along the way are important to understand for all interested participants even if one is not involved in the entire process. Here, we provide an overview of these processes beginning at discovery and preclinical validation of a new molecular imaging agent and using as an exemplar a low molecular weight disease-specific targeted positron emission tomography (PET) agent. Compared to standard drug development requirements, molecular imaging agents may benefit from a regulatory standpoint from their low mass administered doses, they nonetheless still need to go through a series of well-defined steps before they can be considered for Phase 1 human testing. After outlining the discovery and preclinical validation approaches, we will also discuss the nuances of Phase 1, Phase 2 and Phase 3 studies that may culminate in an FDA general use approval. Finally, some post-approval aspects of novel molecular imaging agents are considered.

Clinical and pathological predictors for FDG-PET/CT avidity in patients with marginal zone lymphoma-a retrospective cohort study

BACKGROUND

The clinical value of FDG-PET/CT for staging and monitoring treatment response in patients with aggressive lymphoma is well established. Conversely, its role in the assessment and management of marginal zone lymphoma (MZL) is less conclusive. We aimed to assess clinical, laboratory, and pathological predictors for FDG uptake in these patients, in an attempt to identify MZL patients whose management will benefit from this imaging modality.

METHODS

In this single-center, retrospective cohort study, we included all adult patients diagnosed with MZL at the Rabin Medical Center between January 2006 and December 2020 who underwent FDG-PET/CT at the time of diagnosis. Primary outcomes were FDG avidity (defined as a visual assessment of at least moderate intensity), SUVmax, and SUVliver. Variables such as advanced clinical stage, primary disease site, hemoglobin level (Hb), platelet count (Plt), serum albumin, LDH level, β-2 microglobulin, and Ki 67 index were evaluated univariate and multivariate analysis using logistic and linear regression models. Association between FDG avidity and progression-free and overall survival was evaluated using Kaplan-Meier curves and Cox regression analysis.

RESULTS

A total of 207 MZL patients were included in this study, 76 of whom (36.7%) had FDG-avid disease. Baseline patients' characteristics such as age, gender, and comorbid conditions were similar between patients with and without significant FDG uptake. In a multivariate logistic regression model, non-gastric MALT (OR 4.2, 95% CI 1.78-10), Ki 67 index ≥ 15% (OR 3.64, 95% CI 1.36-9.76), and elevated LDH level (OR 8.6, 95% CI 3.2-22.8) were all associated with positive FDG avidity. In a multivariate linear regression model, a combination of advanced clinical stage, specific disease subtypes, LDH level, and Ki 67 index predicted the value of SUVmax (P value < 0.001; adjusted R² = 33.8%) and SUVmax/SUVliver (P value < 0.001; adjusted R² = 27%). Baseline FDG avidity was associated to PFS and OS only in univariate analyses.

CONCLUSIONS

In this retrospective cohort study, we present prediction models for positive FDG uptake and SUVmax in MZL patients. These models aim to help clinicians choose patients suitable for incorporation of FDG-PET/CT for staging and monitoring disease and reduce the costs of redundant tests.

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.

Clinical Practice Guideline: Follicular Lymphoma—Diagnosis, Treatment, and Follow-up

BACKGROUND

Follicular lymphoma (FL) occurs predominantly at advanced age, with an annual incidence of 3-5 cases per 100 000 inhabitants in Western countries. The clinical course is heterogeneous.

METHODS

For this new guideline, systematic literature searches were conducted in medical databases (MEDLINE, PubMed Central) (up to November 2017) and in the Guidelines International Network (G-I-N), and recent publications were added.

RESULTS

The results of 21 systematic reviews with meta-analyses, 75 randomized controlled trials, and 58 prospective and retrospective studies were evaluated. Lymph-node biopsy is necessary for initial diagnosis of FL. CT scanning of the neck, thorax, and abdomen should be performed to assess how far the disease has spread, together with bone marrow biopsy and, if required, PET/CT. In early FL (stages I and II; 10-15 %), potentially curative radiotherapy combined with an anti-CD 20 antibody is recommended. In advanced disease (stages III and IV), watchful waiting is indicated for patients who have no clinical symptoms and a low tumor burden. Patients with clinical symptoms and/or high tumor burden should receive chemotherapy in combination with an anti-CD 20 antibody, followed by 2 years' maintenance treatment with an anti-CD 20 antibody.

CONCLUSION

Given the good long-term prognosis of FL, the treatment must be chosen with care and thorough follow-up is necessary to ensure detection of late sequelae such as second malignancies or organ damage.

How to manage early-stage follicular lymphoma

INTRODUCTION

Early-stage follicular lymphoma (FL) is characterized by good prognosis and can be cured with involved-field radiotherapy (IF-RT) in most cases. PET scan is a milestone of diagnostic work-up, with the aim of identifying a truly localized disease; however, staging in most of the studies was without PET.

AREAS COVERED

We have searched in MEDLINE (inclusive dates 1994-2020) data about localized FL management. While high-quality evidence is lacking, current guidelines recommend IFRT or involved-site RT as first-line treatment in limited stages FL. Since a significant proportion of disease relapse occurred in non-irradiated areas, it has been hypothesized that occult disease could be present at diagnosis and could persist after RT, contributing to relapse. Available treatment options include watch-and-wait, chemotherapy, RT plus chemo- or chemo-immunotherapy, and RT combined with rituximab (R).

EXPERT OPINION

RT combined with chemotherapy could increase PFS, but a clear OS benefit is lacking and toxic effects could be unacceptable. A promising strategy is represented by R combined with IF-RT, with low relapse rate outside the radiation fields and without the toxicity reported with chemotherapy. The study of prognostic factors in PET-staged patients, the reduction of RT fields and doses, and a response-adapted strategy represent new perspectives to investigate.

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.

FDG PET Hybrid Imaging

Molecular imaging with positron emission tomography (PET) using tumour-seeking radiopharmaceuticals has gained wide acceptance in oncology with many clinical applications. The hybrid imaging modality PET/CT (computed tomography) allows assessing molecular as well as morphologic information at the same time. Therefore, PET/CT represents an efficient tool for whole-body staging and re-staging within one imaging modality. In oncology, the glucose analogue 18-F-fluorodeoxyglucose (FDG) is the most widely used PET/CT radiopharmaceutical in clinical routine. FDG PET and FDG PET/CT have been used for staging and re-staging of tumour patients in numerous studies. This chapter will discuss the use and the main indications of FDG PET/CT in oncology with special emphasis on lung cancer, lymphoma, head and neck cancer, melanoma and breast cancer (among other tumour entities). A review of the current literature is given with respect to primary diagnosis, staging and diagnosis of recurrent disease. Besides its integral role in diagnosis, staging and re-staging of disease in oncology, there is increasing evidence that FDG PET/CT can be used for therapy response assessment (possibly influencing therapeutic management and treatment planning) by evaluating tumour control, which will also be discussed in this chapter.

Whole body FDG-PET/CT for the assessment of bone marrow infiltration in patients with newly diagnosed lymphoma

BACKGROUND

Positron emission tomography-computed tomography (PET-CT) and bone marrow biopsy are currently the common clinical examination of lymphoma infiltration. The aim of this research is to evaluate the value of PET-CT in diagnosis of bone marrow infiltration, clinical staging and pathological typing of lymphoma.

METHODS

153 cases were analyzed retrospectively to compare the consistency of PET-CT and bone marrow biopsy. We analyzed the sensitivity, accuracy and specificity of PET-CT in different clinical pathology of lymphoma.

RESULTS

The PET-CT sensitivity in detecting bone marrow infiltration is 54.3% with a specificity of 80.5% and accuracy of 74.5%. In aggressive B-cell lymphoma (DLBCL, HG-BL) and MZL, PET-CT results of bone marrow infiltration showed high accuracy of 88.1% and 83.3% respectively. The median value of SUVmax in the patients detected to have bone marrow infiltration by BMB was significantly higher than patients with BMB negative results among subgroups of aggressive B-cell lymphoma, MZL and T-NHL (p<.05).

CONCLUSION

PET-CT is significant in detecting bone marrow infiltration in certain pathological types of lymphoma. However pathological inconsistencies still exist between bone marrow biopsy and PET-CT, thus PET-CT cannot completely replace biopsy.

Outcomes of stage I/II follicular lymphoma in the PET era: an international study from the Australian Lymphoma Alliance

Management practices in early-stage (I/II) follicular lymphoma (FL) are variable and include radiation (RT), systemic therapy, or combined modality therapy (CMT). There is a paucity of data regarding maintenance rituximab in this cohort. We conducted an international retrospective study of patients with newly diagnosed early-stage FL staged with positron emission tomography (PET)-computed tomography and bone marrow biopsy. Three hundred sixty-five patients (stage I, n = 221), median age 63 years, treated from 2005-2017 were included, with a median follow-up of 45 months. Management included watchful waiting (WW; n = 85) and active treatment (n = 280). The latter consisted of RT alone (n = 171) or systemic therapy (immunochemotherapy [n = 63] or CMT [n = 46]). Forty-nine systemically treated patients received maintenance rituximab; 72.7% of stage I patients received RT alone, compared to 42.6% with stage II (P < .001). Active therapies yielded comparable overall response rates (P = .87). RT alone and systemic therapy without maintenance rituximab yielded similar progression-free survival (PFS) (hazard ratio [HR], 1.32; 95% confidence interval [CI], 0.77-2.34; P = .96). Maintenance rituximab improved PFS (HR, 0.24; 95% CI, 0.095-0.64; P = .017). The incidence of transformation was lower with systemic therapy compared to RT or WW (HR, 0.20; 95% CI, 0.070-0.61; P = .034). Overall survival was similar among all practices, including WW (P = .40). In the largest comparative assessment of management practices in the modern era, variable practices each resulted in similar excellent outcomes. Randomized studies are required to determine the optimal treatment in early-stage FL.

Practice-based evidence for the clinical benefit of PET/CT-results of the first oncologic PET/CT registry in Germany

PURPOSE

The purpose of this study was to evaluate the impact of PET/CT on clinical management of cancer patients based on a prospective data registry. The study was developed to inform consultations with public health insurances on PET/CT coverage.

METHODS

We evaluated a prospective patient cohort having a clinically indicated PET/CT at a single German University Center from April 2013 to August 2016. The registry collected questionnaire data from requesting physicians on intended patient management before and after PET/CT. A total of 4,504 patients with 5,939 PET/CT examinations were enrolled in the registry, resulting in evaluable data from 3,724 patients receiving 4,754 scans. The impact of PET/CT on patient management was assessed across 22 tumor types, for different indications (diagnosis, staging, suspected recurrence) and different categories of management including treatment (curative or palliative) and non-treatment (watchful waiting, additional imaging, invasive tests).

RESULTS

The most frequent PET/CT indication was tumor staging (59.7%). Melanoma, lung cancer, lymphoma, neuroendocrine tumor and prostate cancer accounted for 70% of cases. Overall, the use of PET/CT resulted in a 37.1% change of clinical management (95% CI, 35.7-38.5), most frequently (30.6%) from an intended non-treatment strategy before PET/CT to active treatment after PET/CT. The frequency of changes ranged from 28.3% for head and neck cancers up to 46.0% for melanomas. The impact of PET/CT was greatest in reducing demands for additional imaging which decreased from 66.1% before PET/CT to 6.1% after PET/CT. Pre-PET/CT planned invasive tests could be avoided in 72.7% of cases. The treatment goal changed after PET/CT in 21.7% of cases, in twice as many cases from curative to palliative therapy than vice versa.

CONCLUSIONS

The data of this large prospective registry confirm that physicians often change their intended management on the basis of PET/CT by initiating treatment and reducing additional imaging as well as invasive tests. This applies to various cancer types and indications.

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.

Outcome of patients with early-stage follicular lymphoma staged with 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) and treated with radiotherapy alone

PURPOSE/OBJECTIVE(S)

To evaluate the impact of positron emission tomography (PET) staging on overall survival (OS) and progression-free survival (PFS) in patients with early-stage (stages I and II) follicular lymphoma (ESFL) treated with radiation therapy alone.

MATERIALS/METHODS

Eighty-five patients with ESFL treated with curative-intent radiation therapy (RT) between December 2000 and May 2011 were identified. Of those, 13 who had no PET staging and 25 who received additional systemic therapy were excluded from the analysis. Thus, we analyzed 47 patients with PET-staged ESFL treated with definitive radiation therapy alone (dose > 23Gy). Tumour features, pre-treatment computed tomography (CT) and PET stage, dose fractionation, and radiation therapy field extent were recorded. The Kaplan-Meier method was used to estimate the OS and PFS. Patterns of failure were assessed as cumulative incidences assuming competing risks.

RESULTS

Median age was 57 years (range 24-83); 43% were females. Most were PET stage 1 (76.6%). Median maximum nodal diameter was 3 cm. Median pre-treatment lactate dehydrogenase (LDH) was 327.5 (range 123-607, upper normal limit = 220). Twenty-six patients (55.3%) had infra-diaphragmatic disease. All received 30-36Gy in 15-24 fractions, with 59.6% treated with involved-field radiation therapy (IFRT) techniques. There was no significant difference in PFS between CT stage I and stage II (HR 1.30 95% CI [0.25-6.72], p = 0.75) with a 5-year PFS of 77% and 78% respectively. However, stage I on PET staging had a significantly better PFS than stage II (HR 4.66 95% CI [1.15-18.8], p = 0.038), with 5-year PFS of 84% and 60% respectively. Ten patients had recurrent disease, with distant disease being the first site of failure in seven patients. Seven-year OS was 91% (95% CI 79-100) for the whole cohort.

CONCLUSION

FDG-PET should be considered an essential element in the evaluation of patients with ESFL being considered for RT.

Clinical management and outcomes of completely resected stage I follicular lymphoma

Recent studies have revealed the clinical and biological features of stage I follicular lymphoma (FL), but information about patients with stage I FL who underwent total resection after tissue biopsy is limited. Among 305 FL patients diagnosed between 2001 and 2013, clinical stage I disease was observed in 36 patients. Of these, 18 patients underwent total resection after diagnostic tissue biopsy. We used ¹⁸F-fluorodeoxyglucose positron emission CT for staging assessment in 13 of 18 patients (72.2%). The median age was 56.5 years. Six patients (33.3%) were male. The soluble interleukin-2 receptor alpha concentration was significantly lower than in patients with residual disease. Among these 18 patients, 7 patients (38.9%) were treated with a "watch-and-wait" (WW) policy, 7 (38.9%) were treated with involved-field irradiation, and 4 (22.2%) received systemic chemotherapy. Patients with resected disease were treated with significantly different strategies from those with residual disease (p = 0.0026). Five patients experienced relapse during follow-up (median follow-up: 48.2 months). All relapses were distant from the primary site, irrespective of treatment strategy. Among all stage I patients, disease resection was not a significant factor for survival (p = 0.9294). Collectively, the choice of treatment strategy was significantly influenced by patient status. Resection status was not significantly associated with survival after several treatment strategies.