Early positron emission tomography (PET) restaging: a predictive final response in Hodgkin's disease patients

PET/CT in Hodgkin Lymphoma: An Update

¹⁸F-FDG-PET/CT is now an integral part of the workup and management of patients with Hodgkin's lymphoma (HL). PET/CT is currently routinely performed for staging and for response assessment at the end of treatment. Interim PET/CT is typically performed after 1-4 of 6-8 chemo/chemoimmunotherapy cycles ± radiation for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics such as the standardized uptake value (SUV), metabolic tumor volume, total lesion glycolysis, and their changes with treatment 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. This review highlights the most relevant applications of PET/CT in HL, its strengths and limitations, as well as recent efforts to implement PET/CT-based metrics as promising tools for precision medicine. Finally, the value of PET/CT for response assessment to immunotherapy is discussed.

A picture is worth a thousand words: a history of diagnostic imaging for lymphoma

The journey from early drawings of Thomas Hodgkin's patients to deep learning with radiomics in lymphoma has taken nearly 200 years, and in many ways, it parallels the journey of medicine. By tracing the history of imaging in clinical lymphoma practice, we can better understand the motivations for current imaging practices. The earliest imaging modalities of the 2D era each had varied, site-dependent sensitivity, and the improved accuracy of imaging studies allowed new diagnostic and therapeutic techniques. First, we review the initial imaging technologies that were applied to understand lymphoma spread and achieve practical guidance for the earliest lymphoma treatments. Next, in the 3D era, we describe how anatomical imaging advances replaced and complemented conventional modalities. Afterward, we discuss how the PET era scans were used to understand response of tumors to treatment and risk stratification. Finally, we discuss the emergence of radiomics as a promising area of research in personalized medicine. We are now able to identify involved lymph nodes and body sites both before and after treatment to offer patients improved treatment outcomes. As imaging methods continue to improve sensitivity, we will be able to use personalized medicine approaches to give targeted and highly focused therapies at even earlier time points, and ideally, we can obtain long-term disease control and cures for lymphomas.

Interim PET-results for prognosis in adults with Hodgkin lymphoma: a systematic review and meta-analysis of prognostic factor studies

BACKGROUND

Hodgkin lymphoma (HL) is one of the most common haematological malignancies in young adults and, with cure rates of 90%, has become curable for the majority of individuals. Positron emission tomography (PET) is an imaging tool used to monitor a tumour's metabolic activity, stage and progression. Interim PET during chemotherapy has been posited as a prognostic factor in individuals with HL to distinguish between those with a poor prognosis and those with a better prognosis. This distinction is important to inform decision-making on the clinical pathway of individuals with HL.

OBJECTIVES

To determine whether in previously untreated adults with HL receiving first-line therapy, interim PET scan results can distinguish between those with a poor prognosis and those with a better prognosis, and thereby predict survival outcomes in each group.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL and conference proceedings up until April 2019. We also searched one trial registry (ClinicalTrials.gov).

SELECTION CRITERIA

We included retrospective and prospective studies evaluating interim PET scans in a minimum of 10 individuals with HL (all stages) undergoing first-line therapy. Interim PET was defined as conducted during therapy (after one, two, three or four treatment cycles). The minimum follow-up period was at least 12 months. We excluded studies if the trial design allowed treatment modification based on the interim PET scan results.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form according to the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS). Two teams of two review authors independently screened the studies, extracted data on overall survival (OS), progression-free survival (PFS) and PET-associated adverse events (AEs), assessed risk of bias (per outcome) according to the Quality in Prognosis Studies (QUIPS) tool, and assessed the certainty of the evidence (GRADE). We contacted investigators to obtain missing information and data.

MAIN RESULTS

Our literature search yielded 11,277 results. In total, we included 23 studies (99 references) with 7335 newly-diagnosed individuals with classic HL (all stages). Participants in 16 studies underwent (interim) PET combined with computed tomography (PET-CT), compared to PET only in the remaining seven studies. The standard chemotherapy regimen included ABVD (16) studies, compared to BEACOPP or other regimens (seven studies). Most studies (N = 21) conducted interim PET scans after two cycles (PET2) of chemotherapy, although PET1, PET3 and PET4 were also reported in some studies. In the meta-analyses, we used PET2 data if available as we wanted to ensure homogeneity between studies. In most studies interim PET scan results were evaluated according to the Deauville 5-point scale (N = 12). Eight studies were not included in meta-analyses due to missing information and/or data; results were reported narratively. For the remaining studies, we pooled the unadjusted hazard ratio (HR). The timing of the outcome measurement was after two or three years (the median follow-up time ranged from 22 to 65 months) in the pooled studies. Eight studies explored the independent prognostic ability of interim PET by adjusting for other established prognostic factors (e.g. disease stage, B symptoms). We did not pool the results because the multivariable analyses adjusted for a different set of factors in each study. Overall survival Twelve (out of 23) studies reported OS. Six of these were assessed as low risk of bias in all of the first four domains of QUIPS (study participation, study attrition, prognostic factor measurement and outcome measurement). The other six studies were assessed as unclear, moderate or high risk of bias in at least one of these four domains. Four studies were assessed as low risk, and eight studies as high risk of bias for the domain other prognostic factors (covariates). Nine studies were assessed as low risk, and three studies as high risk of bias for the domain 'statistical analysis and reporting'. We pooled nine studies with 1802 participants. Participants with HL who have a negative interim PET scan result probably have a large advantage in OS compared to those with a positive interim PET scan result (unadjusted HR 5.09, 95% confidence interval (CI) 2.64 to 9.81, I² = 44%, moderate-certainty evidence). In absolute values, this means that 900 out of 1000 participants with a negative interim PET scan result will probably survive longer than three years compared to 585 (95% CI 356 to 757) out of 1000 participants with a positive result. Adjusted results from two studies also indicate an independent prognostic value of interim PET scan results (moderate-certainty evidence). Progression-free survival Twenty-one studies reported PFS. Eleven out of 21 were assessed as low risk of bias in the first four domains. The remaining were assessed as unclear, moderate or high risk of bias in at least one of the four domains. Eleven studies were assessed as low risk, and ten studies as high risk of bias for the domain other prognostic factors (covariates). Eight studies were assessed as high risk, thirteen as low risk of bias for statistical analysis and reporting. We pooled 14 studies with 2079 participants. Participants who have a negative interim PET scan result may have an advantage in PFS compared to those with a positive interim PET scan result, but the evidence is very uncertain (unadjusted HR 4.90, 95% CI 3.47 to 6.90, I² = 45%, very low-certainty evidence). This means that 850 out of 1000 participants with a negative interim PET scan result may be progression-free longer than three years compared to 451 (95% CI 326 to 569) out of 1000 participants with a positive result. Adjusted results (not pooled) from eight studies also indicate that there may be an independent prognostic value of interim PET scan results (low-certainty evidence). PET-associated adverse events No study measured PET-associated AEs.

AUTHORS' CONCLUSIONS

This review provides moderate-certainty evidence that interim PET scan results predict OS, and very low-certainty evidence that interim PET scan results predict progression-free survival in treated individuals with HL. This evidence is primarily based on unadjusted data. More studies are needed to test the adjusted prognostic ability of interim PET against established prognostic factors.

Clinical characteristics of interim-PET negative patients with a positive end PET from the prospective HD08-01 FIL study

FDG-positron emission tomography (PET) performed early during therapy in advanced Hodgkin lymphoma patients has been confirmed as being important for progression-free survival. A group of patients with a negative interim-PET (i-PET) showed a positive end induction PET (e-PET). The aim of this study was to evaluate the clinical characteristics of patients with a positive e-PET as a secondary end point of the HD0801 study. A total of 519 patients with advanced-stage de novo Hodgkin lymphoma received initial treatment and underwent an i-PET. Patients with negative results continued the standard treatment. i-PET negative patients were then evaluated for response with an e-PET and those patients found to have a positive one were also then given a salvage therapy. Among 409 i-PET negative, 16 interrupted the therapy, 393 patients were evaluated with an e-PET, and 39 were positive. Sixteen out of 39 underwent a diagnostic biopsy and 15 were confirmed as HD. Seventeen out of 39 e-PET were reviewed according to the Deauville Score and, in sixteen, it was confirmed positive (10 DS 5, 6 DS 4). With the exception of high LDH value at diagnosis (p = 0.01; HR 95% CI 1.18-4.89), no clinical characteristics were significantly different in comparison with e-PET negative patients. Positive e-PET after a negative i-PET has a worse outcome when compared with i-PET positive patients salvaged with therapy intensification. It was not possible to identify clinical characteristics associated with a positive e-PET.

Interim PET-results for prognosis in adults with Hodgkin lymphoma: a systematic review and meta-analysis of prognostic factor studies

BACKGROUND

Hodgkin lymphoma (HL) is one of the most common haematological malignancies in young adults and, with cure rates of 90%, has become curable for the majority of individuals. Positron emission tomography (PET) is an imaging tool used to monitor a tumour's metabolic activity, stage and progression. Interim PET during chemotherapy has been posited as a prognostic factor in individuals with HL to distinguish between those with a poor prognosis and those with a better prognosis. This distinction is important to inform decision-making on the clinical pathway of individuals with HL.

OBJECTIVES

To determine whether in previously untreated adults with HL receiving first-line therapy, interim PET scan results can distinguish between those with a poor prognosis and those with a better prognosis, and thereby predict survival outcomes in each group.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL and conference proceedings up until April 2019. We also searched one trial registry (ClinicalTrials.gov).

SELECTION CRITERIA

We included retrospective and prospective studies evaluating interim PET scans in a minimum of 10 individuals with HL (all stages) undergoing first-line therapy. Interim PET was defined as conducted during therapy (after one, two, three or four treatment cycles). The minimum follow-up period was at least 12 months. We excluded studies if the trial design allowed treatment modification based on the interim PET scan results.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form according to the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS). Two teams of two review authors independently screened the studies, extracted data on overall survival (OS), progression-free survival (PFS) and PET-associated adverse events (AEs), assessed risk of bias (per outcome) according to the Quality in Prognosis Studies (QUIPS) tool, and assessed the certainty of the evidence (GRADE). We contacted investigators to obtain missing information and data.

MAIN RESULTS

Our literature search yielded 11,277 results. In total, we included 23 studies (99 references) with 7335 newly-diagnosed individuals with classic HL (all stages).Participants in 16 studies underwent (interim) PET combined with computed tomography (PET-CT), compared to PET only in the remaining seven studies. The standard chemotherapy regimen included ABVD (16) studies, compared to BEACOPP or other regimens (seven studies). Most studies (N = 21) conducted interim PET scans after two cycles (PET2) of chemotherapy, although PET1, PET3 and PET4 were also reported in some studies. In the meta-analyses, we used PET2 data if available as we wanted to ensure homogeneity between studies. In most studies interim PET scan results were evaluated according to the Deauville 5-point scale (N = 12).Eight studies were not included in meta-analyses due to missing information and/or data; results were reported narratively. For the remaining studies, we pooled the unadjusted hazard ratio (HR). The timing of the outcome measurement was after two or three years (the median follow-up time ranged from 22 to 65 months) in the pooled studies.Eight studies explored the independent prognostic ability of interim PET by adjusting for other established prognostic factors (e.g. disease stage, B symptoms). We did not pool the results because the multivariable analyses adjusted for a different set of factors in each study.Overall survivalTwelve (out of 23) studies reported OS. Six of these were assessed as low risk of bias in all of the first four domains of QUIPS (study participation, study attrition, prognostic factor measurement and outcome measurement). The other six studies were assessed as unclear, moderate or high risk of bias in at least one of these four domains. Nine studies were assessed as high risk, and three studies as moderate risk of bias for the domain study confounding. Eight studies were assessed as low risk, and four studies as high risk of bias for the domain statistical analysis and reporting.We pooled nine studies with 1802 participants. Participants with HL who have a negative interim PET scan result probably have a large advantage in OS compared to those with a positive interim PET scan result (unadjusted HR 5.09, 95% confidence interval (CI) 2.64 to 9.81, I² = 44%, moderate-certainty evidence). In absolute values, this means that 900 out of 1000 participants with a negative interim PET scan result will probably survive longer than three years compared to 585 (95% CI 356 to 757) out of 1000 participants with a positive result.Adjusted results from two studies also indicate an independent prognostic value of interim PET scan results (moderate-certainty evidence).Progression-free survival Twenty-one studies reported PFS. Eleven out of 21 were assessed as low risk of bias in the first four domains. The remaining were assessed as unclear, moderate or high risk of bias in at least one of the four domains. Eleven studies were assessed as high risk, nine studies as moderate risk and one study as low risk of bias for study confounding. Eight studies were assessed as high risk, three as moderate risk and nine as low risk of bias for statistical analysis and reporting.We pooled 14 studies with 2079 participants. Participants who have a negative interim PET scan result may have an advantage in PFS compared to those with a positive interim PET scan result, but the evidence is very uncertain (unadjusted HR 4.90, 95% CI 3.47 to 6.90, I² = 45%, very low-certainty evidence). This means that 850 out of 1000 participants with a negative interim PET scan result may be progression-free longer than three years compared to 451 (95% CI 326 to 569) out of 1000 participants with a positive result.Adjusted results (not pooled) from eight studies also indicate that there may be an independent prognostic value of interim PET scan results (low-certainty evidence).PET-associated adverse eventsNo study measured PET-associated AEs.

AUTHORS' CONCLUSIONS

This review provides moderate-certainty evidence that interim PET scan results predict OS, and very low-certainty evidence that interim PET scan results predict progression-free survival in treated individuals with HL. This evidence is primarily based on unadjusted data. More studies are needed to test the adjusted prognostic ability of interim PET against established prognostic factors.

The role of PET/CT in the modern treatment of Hodgkin lymphoma

Classical Hodgkin Lymphoma is distinguished from other lymphomas by its peculiar biology and heterogeneous chemosensitivity. Most of the patients respond to the standard first-line treatment and are cured, however, in selected cases, the disease relapses or remains primarily refractory. Among predictive/prognostic factors ¹⁸FDG positron emission tomography (PET), fully integrated with computed tomography (PET/CT) proved to be extremely useful in identifying patients with poor prognosis at the time of diagnosis, during and at the end of treatment. The aim of this review is to present the current role of PET/CT in cHL at staging, interim and end of therapy assessment and its ability to guide treatment with a response- and risk-adapted strategy in clinical practice. Finally, quantitative PET measurement and the concurrent use of PET with selected biomarkers are discussed.

Predictive approaches for post-therapy PET/CT in patients with extranodal natural killer/T-cell lymphoma: a retrospective study

PURPOSE

The aim of this study was to assess the prognostic capacity of three methods of fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT analysis carried out after therapy in patients with extranodal natural killer/T-cell lymphoma (ENKTL). The three methods of PET/CT analysis included the International Harmonization Project (IHP) criteria, the Deauville five-point scale (5-PS), and standardized uptake value (SUV)-based assessment.

PATIENTS AND METHODS

Fifty-nine patients diagnosed with ENKTL were enrolled. Each patient underwent three F-FDG PET/CT scans: (i) baseline, (ii) after two to four cycles of chemotherapy (early response assessment), and (iii) at the end of treatment (evaluation of the final response). Post-therapy F-FDG PET/CT results were determined on the basis of IHP criteria, 5-PS, and change in the maximum F-FDG uptake (ΔSUVmax). IHP criteria, 5-PS, and ΔSUVmax were then examined for their ability to predict progression-free survival (PFS) and overall survival (OS).

RESULTS

Over a median follow-up of 25 months, 5-PS and ΔSUVmax were significant predictors of PFS and OS. After multivariate analysis, 5-PS could predict PFS (P=0.008) and OS (P=0.002) independently. ΔSUVmax was found to be an independent predictor of PFS (P=0.019), but not OS, and had a lower accuracy and positive predictive value than 5-PS.

CONCLUSION

Post-therapy PET/CT analysis using the 5-PS is more able to predict survival than analysis with IHP or [INCREMENT]SUVmax in ENKTL patients.

Real-life Experience for Integration of PET-CT in the Treatment of Hodgkin Lymphoma in Lebanon

BACKGROUND

Hodgkin lymphoma (HL) is a highly curable disease; < 80% of patients will achieve long-term survival. Positron emission tomography-computed tomography (PET-CT) has played a major role in the evaluation of both disease staging and response and has become an essential component in tailoring patients' treatment. We report the effect of integrating PET-CT into the management of HL in Lebanon.

PATIENTS AND METHODS

We analyzed the data regarding the usage of PET-CT at diagnosis, during treatment (interim PET), and at the end of treatment. We also analyzed the PET-CT findings from 2009 to 2015.

RESULTS

The first PET-CT system was introduced in Lebanon in April 2002 but was not used for the evaluation of HL. Early in 2009, we started to incorporate PET-CT into the treatment of HL. By the end of 2009, 70% of patients were undergoing PET-CT at diagnosis and at the end of treatment. This proportion remained constant until 2013, when an increase occurred, with ≤ 94% of patients undergoing PET-CT at diagnosis. The usage of CT at diagnosis decreased significantly from 70% before 2009 to 52% after 2015. In contrast, CT usage at the end of treatment has fluctuated from 10% in 2009 to 0% in 2012, 2013, and 2014 and 11.76% in 2015.

CONCLUSION

Functional imaging techniques are increasing in popularity compared with anatomic imaging. The usage of PET-CT has emerged as a highly valuable staging and follow-up method in the treatment of HL 8 years after the introduction of PET in Lebanon. PET was used first to improve the staging, then to evaluate the treatment response, and, recently, to tailor therapy according to the response.

Early-stage Hodgkin lymphoma outcomes after combined modality therapy according to the post-chemotherapy 5-point score: can residual pet-positive disease be cured with radiotherapy alone?

Early-stage classical Hodgkin lymphoma (HL) patients are evaluated by an end-of-chemotherapy positron emission tomography-computed tomography (eoc-PET-CT) after doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) and before radiation therapy (RT). We determined freedom from progression (FFP) in patients treated with ABVD and RT according to the eoc-PET-CT 5-point score (5PS). Secondarily, we assessed whether patients with a positive eoc-PET-CT (5PS of 4-5) can be cured with RT alone. The cohort comprised 174 patients treated for stage I-II HL with ABVD and RT alone. ABVD was given with a median of four cycles and RT with a median dose of 30·6 Gy. Five-year FFP was 97%. Five-year FFP was 100% (0 relapses/98 patients) for patients with a 5PS of 1-2, 97% (2/65) for a 5PS of 3, 83% (1/8) for a 5PS of 4, and 67% (1/3) for a 5PS of 5 (P < 0·001). Patients with positive eoc-PET-CT scans who were selected for salvage RT alone had experienced a very good partial response to ABVD. Risk factors for recurrence in this subgroup included a small reduction in tumour size and a 'bounce' in ≥1 PET-CT parameter (reduction then rise from interim to final scan). Thus, a positive eoc-PET-CT is associated with inferior FFP; however, appropriately selected patients can be cured with RT alone.

ACR Appropriateness Criteria® Hodgkin Lymphoma-Favorable Prognosis Stage I and II

This topic addresses the treatment of newly diagnosed patients with favorable prognosis stage I and II Hodgkin lymphoma. In most cases, combined modality therapy (chemotherapy followed by involved site radiation therapy) constitutes the current standard of care. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. By combining the most recent medical literature and expert opinion, this revised guideline can aid clinicians in the appropriate use of combined modality therapy for favorable prognosis stage I and II Hodgkin lymphoma. Increasing information about the late effects of treatment has led to attempts to decrease toxicity by using less chemotherapy (decreased duration and/or intensity or different agents) and less radiation therapy (reduced volume and/or dose) while maintaining excellent efficacy.

Risk-adapted transplant strategies for high-risk Hodgkin lymphoma: are we there?

PURPOSE OF REVIEW

The treatment of high-risk classic Hodgkin lymphoma (cHL) patients remains challenging, especially after autologous stem cell transplant (ASCT) failure. Moreover, the outcome of chemorefractory patients is still poor.

RECENT FINDINGS

The development of novel targeted therapies has changed the therapeutic options for high-risk patients. To improve outcome, treatment algorithms should integrate up-front, newly established prognostic markers. Tandem ASCT instead of single ASCT has been proposed as an option to improve outcome for high-risk patients. Availability of less toxic reduced intensity conditioning regimens and recent development in haploidentical transplantation have widened applicability and improved outcomes of allo-hematopoietic cell transplantation. Their exact role in cHL is still controversial and there is no consensus on the optimal transplantation strategy. In this context, results of tandem ASCT should also be compared with those of the autologous/reduced intensity conditioning-allo tandem approach. In this review, we discuss how transplantation strategies (auto and allo) can fit into the salvage treatment plan for patients with relapsed/refractory cHL, taking into account the new drugs available and integrating modern risk assessment.

SUMMARY

We speculated that improvements could be achieved by transplanting patients in earlier phases of their disease, if necessary after 'bridging' using the new drugs, and we propose an algorithm integrating the different treatment options.

The role of FDG-PET in Hodgkin lymphoma

18-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) is currently the most valuable imaging technique in Hodgkin lymphoma. Since its first use in lymphomas in the 1990s, it has become the gold standard in the staging and end-of-treatment remission assessment in patients with Hodgkin lymphoma. The possibility of using early (interim) PET during first-line therapy to evaluate chemosensitivity and thus personalize treatment at this stage holds great promise, and much attention is now being directed toward this goal. With high probability, it is believed that in the near future, the result of interim PET-CT would serve as a compass to optimize treatment. Also the role of PET in pre-transplant assessment is currently evolving. Much controversy surrounds the possibility of detecting relapse after completed treatment with the use of PET in surveillance in the absence of symptoms suggestive of recurrence and the results of published studies are rather discouraging because of low positive predictive value. This review presents current knowledge about the role of 18-FDG-PET/CT imaging at each point of management of patients with Hodgkin lymphoma.

The evolving role of response-adapted PET imaging in Hodgkin lymphoma

(18)F-fluorodeoxyglucose positron emission tomography with (FDG-PET) has a well-established role in the pre- and post-treatment staging of Hodgkin lymphoma (HL), however its use as a predictive therapeutic tool via responded-adapted therapy continues to evolve. There have been a multitude of retrospective and noncontrolled clinical studies showing that early (or interim) FDG-PET is highly prognostic in HL, particularly in the advanced-stage setting. Response-adapted treatment approaches in HL are attempting to diminish toxicity for low-risk patients by minimizing therapy, and conversely, intensify treatment for high-risk patients. Results from phase III noninferiority studies in early-stage HL with negative interim FDG-PET that randomized patients to chemotherapy alone versus combined modality therapy showed a continued small improvement in progression-free survival for patients who did not receive radiation. Preliminary reports of data escalating therapy for positive interim FDG-PET in early-stage HL and for de-escalation of therapy [i.e. bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine and prednisone (BEACOPP)] for negative interim FDG-PET in advanced stage HL (i.e. deletion of bleomycin) have demonstrated improved outcomes. Maturation of these studies and continued follow up of all response-adapted studies are needed. Altogether, the treatment of HL remains an individualized clinical management choice for physicians and patients. Continued refinement and optimization of FDG-PET is needed, including within the context of targeted therapeutic agents. In addition, a number of new and novel techniques of functional imaging, including metabolic tumor volume and tumor proliferation, are being explored in order to enhance staging, characterization, prognostication and ultimately patient outcome.

Post-ABVD/pre-radiotherapy (18)F-FDG-PET provides additional prognostic information for early-stage Hodgkin lymphoma: a retrospective analysis on 165 patients

OBJECTIVE

To evaluate the prognostic role of both interim fluorine-18 fludeoxyglucose positron emission tomography (i-(18)F-FDG-PET) and end-of-chemotherapy fluorine-18 fludeoxyglucose positron emission tomography (eoc-(18)F-FDG-PET) in patients with early-stage Hodgkin lymphoma (HL).

METHODS

We screened 257 patients with early-stage HL treated with combined modality therapy between March 2003 and July 2011. All were staged using fluorine-18 fludeoxyglucose positron emission tomography ((18)F-FDG-PET) before chemotherapy and after two doxorubicin, bleomycin, vinblastine and dacarbazine cycles (i-(18)F-FDG-PET); 165 patients were also evaluated by (18)F-FDG-PET at the end of chemotherapy (eoc-(18)F-FDG-PET).

RESULTS

After revision, 85% of patients were negative for i-(18)F-FDG-PET and 15% were positive. After eoc-(18)F-FDG-PET revision, 23 patients had a positive scan. The median follow-up was 56 months. The 5-year overall survival (OS) and progression-free survival (PFS) for the whole cohort were 97.5% and 95.6%, respectively. For i-(18)F-FDG-PET-negative and i-(18)F-FDG-PET-positive patients, the 5-year PFS rates were 98% and 84%, respectively; for eoc-(18)F-FDG-PET-negative and eoc-(18)F-FDG-PET-positive patients, the 5-year PFS rates were 97% and 78%, respectively. Combining the i-(18)F-FDG-PET and eoc-(18)F-FDG-PET results, the 5-year PFS were 97%, 100% and 82% in negative/negative, positive/negative and positive/positive groups, respectively. The 5-year OS rates were 98% and 83% in eoc-(18)F-FDG-PET-negative and eoc-(18)F-FDG-PET-positive patients, respectively; the 5-year OS was 98%, 100% and 83% in negative/negative, positive/negative and positive/positive groups, respectively.

CONCLUSION

This study provides additional information on the prognostic role of i-(18)F-FDG-PET and eoc-(18)F-FDG-PET in early-stage HL. As data are accumulating and the clinical scenario is rapidly evolving, we might need to rethink the use of (18)F-FDG-PET as a prognostic marker for early-stage HL in the near future.

ADVANCES IN KNOWLEDGE

This study provides additional information on the prognostic role of i-(18)F-FDG-PET and eoc-(18)F-FDG-PET in early-stage HL. On the basis of the present data, we may suggest to use eoc-(18)F-FDG-PET as a strong prognostic marker, especially for patients with i-(18)F-FDG-PET positivity.

Interim Positron Emission Tomography Response-Adapted Therapy in Advanced-Stage Hodgkin Lymphoma: Final Results of the Phase II Part of the HD0801 Study

PURPOSE

The clinical impact of positron emission tomography (PET) evaluation performed early during first-line therapy in patients with advanced-stage Hodgkin lymphoma, in terms of providing a rationale to shift patients who respond poorly onto a more intensive regimen (PET response-adapted therapy), remains to be confirmed.

PATIENTS AND METHODS

The phase II part of the multicenter HD0801 study involved 519 patients with advanced-stage de novo Hodgkin lymphoma who received an initial treatment with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) and who underwent an early ifosfamide-containing salvage treatment followed by stem-cell transplantation if they showed a positive PET evaluation after two cycles of chemotherapy (PET2). The primary end point was 2-year progression-free survival calculated for both PET2-negative patients (who completed a full six cycles of ABVD treatment) and PET2-positive patients. Overall survival was a secondary end point.

RESULTS

In all, 103 of the 512 evaluable patients were PET2 positive. Among them, 81 received the scheduled salvage regimen with transplantation, 15 remained on ABVD (physician's decision, mostly because of minimally positive PET2), five received an alternative treatment, and two were excluded because of diagnostic error. On intention-to-treat analysis, the 2-year progression-free survival was 76% for PET2-positive patients (regardless of the salvage treatment they received) and 81% for PET2-negative patients.

CONCLUSION

Patients with advanced-stage Hodgkin lymphoma for whom treatment was at high risk of failing appear to benefit from early treatment intensification with autologous transplantation, as indicated by the possibility of successful salvage treatment in more than 70% of PET2-positive patients through obtaining the same 2-year progression-free survival as the PET2-negative subgroup.

In vivo treatment sensitivity testing with positron emission tomography/computed tomography after one cycle of chemotherapy for Hodgkin lymphoma

PURPOSE

Negative [(18)F]fluorodeoxyglucose (FDG) -positron emission tomography (PET)/computed tomography (CT) after two cycles of chemotherapy indicates a favorable prognosis in Hodgkin lymphoma (HL). We hypothesized that the negative predictive value would be even higher in patients responding rapidly enough to be PET negative after one cycle. This prospective study aimed to assess the prognostic value of PET after one cycle of chemotherapy in HL and to assess the dynamics of FDG uptake after one cycle (PET1) and after two cycles (PET2).

PATIENTS AND METHODS

All PET scans were read by two blinded, independent reviewers in different countries, according to the Deauville five-point scale. The main end point was progression-free survival (PFS) after 2 years.

RESULTS

A total of 126 patients were included, and all had PET1; 89 patients had both PET1 and PET2. The prognostic value of PET1 was statistically significant with respect to both PFS and overall survival. Two-year PFS for PET1-negative and PET1-positive patients was 94.1% and 40.8%, respectively. Among those with both PET1 and PET2, 2-year PFS was 98.3% and 38.5% for PET1-negative and PET1-positive patients and 90.2% and 23.1% for PET2-negative and PET2-positive patients, respectively. No PET1-negative patient was PET2 positive.

CONCLUSION

PET after one cycle of chemotherapy is highly prognostic in HL. No other prognostic tool identifies a group of patients with HL with a more favorable outcome than those patients with a negative PET1. In the absence of precise pretherapeutic predictive markers, PET1 is the best method for response-adapted strategies designed to select patients for less intensive treatment.

Clinical features and treatment outcomes of Hodgkin's lymphoma in Hong Kong Chinese

INTRODUCTION

Little information is available on the outcomes of Hodgkin's lymphoma in Chinese patients. We analyzed the clinical and histopathological characteristics, treatment types, clinical course and treatment outcomes of Hong Kong Chinese patients.

MATERIAL AND METHODS

Patients with Hodgkin's lymphoma diagnosed from January 1991 to December 2010 were recruited. A retrospective analysis of these patients was performed.

RESULTS

Sixty-seven Chinese patients (38 males and 29 females) were identified and the median age was 36 (range 16-80). Nodular sclerosis was the most common histology (54%), followed by mixed cellularity (36%). Twenty-four patients had early favorable, 20 patients had early unfavorable and 23 patients had advanced-stage diseases. The most common presentation was palpable lymph node or mass (85%) followed by fever, weight loss, night sweating and mediastinal mass. Ninety percent of patients received chemotherapy and 40% received radiotherapy as consolidation. Seven patients with stage I lymphoma received radiotherapy alone. ABVD (doxorubicin, bleomycin, vinblastine and dacarbazine) was the most commonly used chemotherapeutic regimen. Following treatment, 87% of patients achieved complete remission. Six patients relapsed after first remission and 3 achieved second remission after re-induction therapy. The 5-year overall survival of the entire cohort was 89% and the freedom from treatment failure (FFTF) at 5 years was 82%. The 5-year overall survival rate for early favorable, early unfavorable and advanced stages was 95.7%, 95.0% and 74.7%, respectively.

CONCLUSIONS

Despite the relatively low incidence of Hodgkin's lymphoma in Hong Kong Chinese, the treatment outcomes are comparable to Caucasian patients.

The predictive role of interim positron emission tomography for Hodgkin lymphoma treatment outcome is confirmed using the interpretation criteria of the Deauville five-point scale

A retrospective, international, multicenter study was undertaken to assess: (i) the prognostic role of 'interim' positron emission tomography performed during treatment with doxorubicin, bleomycin, vinblastine and dacarbazine in patients with Hodgkin lymphoma; and (ii) the reproducibility of the Deauville five-point scale for the interpretation of interim positron emission tomography scan. Two hundred and sixty patients with newly diagnosed Hodgkin lymphoma were enrolled. Fifty-three patients with early unfavorable and 207 with advanced-stage disease were treated with doxorubicin, bleomycin, vinblastine and dacarbazine ± involved-field or consolidation radiotherapy. Positron emission tomography scan was performed at baseline and after two cycles of chemotherapy. Treatment was not changed according to the results of the interim scan. An international panel of six expert reviewers independently reported the scans using the Deauville five-point scale, blinded to treatment outcome. Forty-five scans were scored as positive (17.3%) and 215 (82.7%) as negative. After a median follow up of 37.0 (2-110) months, 252 patients are alive and eight have died. The 3-year progression-free survival rate was 83% for the whole study population, 28% for patients with interim positive scans and 95% for patients with interim negative scans (P<0.0001). The sensitivity, specificity, and negative and positive predictive values of interim positron emission tomography scans for predicting treatment outcome were 0.73, 0.94, 0.94 and 0.73, respectively. Binary concordance amongst reviewers was good (Cohen's kappa 0.69-0.84). In conclusion, the prognostic role and validity of the Deauville five-point scale for interpretation of interim positron emission tomography scans have been confirmed by the present study.

Prognostic value of interim positron emission tomography in patients with peripheral T-cell lymphoma

The definition of the role of positron emission tomography (PET) in peripheral T-cell lymphomas (PTCLs) is still under investigation. The purpose of the present observational retrospective study was to assess the early prognostic value of PET after the first three cycles of therapy (PET+3), evaluating visual data in de novo PTCL patients treated in first line with standard chemotherapy and followed by both PET and computed tomography scan. Of 27 PET+3-negative patients, 19 also had a negative PET at the end of treatment (PET+6), whereas 8 of 27 had a positive final one; 6 of 7 PET+3-positive patients had a positive PET+6, whereas only 1 patient had a negative PET+6. Estimated overall survival plotted according to PET+3 results showed 78.6% for negative patients and 21.4% for positive patients at 88.7 months with a significant difference. Patients with negative PET+3 had superior progression-free survival of 72.6% compared with 16.7% of PET+3-positive patients. At the time of this analysis, 17 of 19 (89.5%) patients with negative PET+3 are in continuous complete response (CCR) and only 1 of 7 (14.2%) patients with positive PET+3 is still in CCR. In conclusion, our results indicate that positive PET+3 is predictive of a worse outcome in PTCL, and this significant statistical difference between the two curves could be clinically informative. Larger and prospective studies and harmonization of PET reading criteria are needed.

Baseline metabolic tumour volume is an independent prognostic factor in Hodgkin lymphoma

PURPOSE

The presence of a bulky tumour at staging in Hodgkin lymphoma (HL) is a predictor of a poor outcome. The total metabolic tumour volume at baseline (TMTV0) computed on PET may improve the evaluation of tumour burden. To explore the clinical usefulness of TMTV0, we compared the prognostic value of TMTV0, tumour bulk and interim PET response in a retrospective single-centre study.

METHODS

From 2007 to 2010, 59 consecutive patients with a first diagnosis of HL were treated in our institution. PET was done at baseline (PET0) and after two cycles of chemotherapy (PET2), and treatment was not modified according to the PET2 result. TMTV0 was measured with a semiautomatic method using a 41 % SUVmax threshold. SUVmax reduction between PET0 and PET2 (ΔSUVmaxPET0-2) was also computed. Based on ROC analysis, patients with a ΔSUVmaxPET0-2 >71 % were considered good responders and a TMTV0 >225 ml was considered to represent hypermetabolic bulky disease.

RESULTS

Median TMTV0 was 117 ml and 17 patients (29 %) had a TMTV0 >225 ml. TMTV0 (>225 ml vs. ≤225 ml) and tumour bulk (<10 cm vs. ≥10 cm) were predictive of 4-year PFS: 42 % vs. 85 % (p = 0.001) and 44 % vs. 79 % (p < 0.03), respectively. In multivariate analysis, using ΔSUVmaxPET0-2, TMTV0 and bulky tumour as covariates, only ΔSUVmaxPET0-2 (p = 0.0005, RR 6.3) and TMTV0 (p < 0.006, RR 4.4) remained independent predictors of PFS. Three prognosis groups were thus identified: ΔSUVmaxPET0-2 >71 % and TMTV0 ≤225 ml (n = 37, 63 %), ΔSUVmaxPET0-2 = <71 % or TMTV0 >225 ml (n = 17, 29 %), and ΔSUVmaxPET0-2 = <71 % and TMTV0 >225 ml (n = 5, 8 %). In these three groups the 4-year PFS rates were 92 %, 49 %, and 20 % (p < 0.0001), respectively.

CONCLUSION

TMTV0 is more relevant than tumour bulk for predicting the outcome in patients with HL, and adds a significant prognostic insight to interim PET response assessment. The combination of TMTV0 and ΔSUVmaxPET0-2 made it possible to identify three subsets of HL patients with different outcomes. This may guide clinicians in their choice of therapeutic strategy.

Factors affecting intrapatient liver and mediastinal blood pool ¹⁸F-FDG standardized uptake value changes during ABVD chemotherapy in Hodgkin's lymphoma

PURPOSE

The aim of our study was to assess the intrapatient variability of 2-deoxy-2-((18)F)-fluoro-D-glucose ((18)F-FDG) uptake in the liver and in the mediastinum among patients with Hodgkin's lymphoma (HL) treated with doxorubicin (Adriamycin), bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy (CHT).

METHODS

The study included 68 patients (30 men, 38 women; mean age 32 ± 11 years) with biopsy-proven HL. According to Ann Arbor criteria, 6 were stage I, 34 were stage II, 12 were stage 3 and 16 were stage 4. All of them underwent a baseline (PET0) and an interim (PET2) (18)F-FDG whole-body positron emission tomography (PET)/CT. All patients were treated after PET0 with two ABVD cycles for 2 months that ended 15 ± 5 days prior to the PET2 examination. All patients were further evaluated 15 ± 6 days after four additional ABVD cycles (PET6). None of the patients presented a serum glucose level higher than 107 mg/dl. The mean and maximum standardized uptake values (SUV) of the liver and mediastinum were calculated using the same standard protocol for PET0, PET2 and PET6, respectively. Data were examined by means of the Wilcoxon matched pairs test and linear regression analysis.

RESULTS

The main results of our study were an increased liver SUVmean in PET2 (1.76 ± 0.35) as compared with that of PET0 (1.57 ± 0.31; p < 0.0001) and PET6 (1.69 ± 0.28; p = 0.0407). The same results were obtained when considering liver SUVmax in PET2 (3.13 ± 0.67) as compared with that of PET0 (2.82 ± 0.64; p < 0.0001) and PET6 (2.96 ± 0.52; p = 0.0105). No significant differences were obtained when comparing mediastinum SUVmean and SUVmax in PET0, PET2 and PET6 (p > 0.05). Another finding is a relationship in PET0 between liver SUVmean and SUVmax with the stage, which was lower in those patients with advanced disease (r (2) = 0.1456 and p = 0.0013 for SUVmean and r (2) = 0.1277 and p = 0.0028 for SUVmax).

CONCLUSION

The results of our study suggest that liver (18)F-FDG uptake is variable in patients with HL during the CHT treatment and the disease course and should be considered carefully when used to define the response to therapy in the interim PET in HL.

Current role of FDG PET/CT in lymphoma

The management approach in Hodgkin's (HL) and high-grade non-Hodgkin's lymphomas (NHL) has shifted towards reducing the toxicity and long-term adverse effects associated with treatment while maintaining favorable outcomes in low-risk patients. The success of an individualized treatment strategy depends largely on accurate diagnostic tests both at staging and during therapy. In this regard, positron emission tomography (PET) using fluorodeoxyglucose (FDG) with computed tomography (CT) has proved effective as a metabolic imaging tool with compelling evidence supporting its superiority over conventional modalities, particularly in staging and early evaluation of response. Eventually, this modality was integrated into the routine staging and restaging algorithm of lymphomas. This review will summarize the data on the proven and potential utility of PET/CT imaging for staging, response assessment, and restaging, describing current limitations of this imaging modality.

Interim 18F-FDG PET in Hodgkin lymphoma: would PET-adapted clinical trials lead to a paradigm shift?

Hodgkin lymphoma (HL) is a curable disease with currently available chemotherapy regimens. Major late morbidities can potentially be avoided in most limited-stage HL patients if the treatment can be adapted to the patient's early response profile. The therapy efficacy can also be increased early during therapy in nonresponding HL patients with the addition of involved-field radiation therapy or a switch to an escalated therapy protocol, particularly in advanced-stage or unfavorable-risk patients. (18)F-FDG PET is a well-established surrogate for tumor chemosensitivity early during therapy. The ongoing PET-adaptive clinical trials are testing the hypothesis that a decision can reliably be made on escalating or deescalating therapy based on interim PET results. Discussed in this review is the integral role of interim (18)F-FDG PET in HL, challenges, critical issues to improve its accuracy, and the observations from completed interim PET studies and ongoing PET-adaptive clinical trials.

State-of-the-Art Research on "Lymphomas: Role of Molecular Imaging for Staging, Prognostic Evaluation, and Treatment Response"

Lymphomas are heterogeneous but potentially curable group of neoplasms. Treatment of lymphomas has rapidly evolved overtime with significant improvement in the cure rate and reductions in treatment-related toxicities. Despite excellent results, treatment programs are continued to be developed to achieve better curative and safety profiles. In these patients individualized therapy schemes can be devised based on a well-defined risk categorization. The therapy efficacy can be increased early during therapy in non-responding patients with escalated therapy protocols or with the addition of radiation therapy, particularly, in advanced-stage or unfavorable risk patients. The increasing availability of positron emission tomography using 18F-fluorodeoxyglucose, particularly fused with computed tomography (FDG-PET/CT) has lead to the integration of this modality into the routine staging and restaging for lymphoma with convincing evidence that it is a more accurate imaging modality compared with conventional imaging techniques. FDG-PET/CT is also is a promising surrogate for tumor chemosensitivity early during therapy. This review will summarize published data on the utility of FDG-PET/CT imaging in the staging, restaging, and predicting therapy response in patients with lymphoma.

The role of fluorodeoxyglucose positron emission tomography-computerized tomography in resolving therapeutic dilemmas in pediatric Hodgkin lymphoma

Introduction:

Hodgkin lymphoma (HL) is a highly curable lymphoma with cure rates of over 80% and even higher with limited stage disease. Computerized tomography (CT) scan is currently the recommended modality in staging and assessment of response to therapy in patients with HL. However, CT has its limitations. This study describes our experience with patients of HL where fluorodeoxyglucose positron emission tomography (FDG-PET)-CT scan helped decide further management, after completion of chemotherapy.

Methodology:

This is a retrospective review of the records of children diagnosed with HL at our center. Patients with post-treatment CT scan showing evidence of residual disease, who underwent FDG-PET-CT for deciding further management, were included in the study.

Results:

Thirty one patients were diagnosed with HL during this period. Nine patients were eligible and underwent PET-CT. In 8 out of 9 patients, PET-CT showed no scan evidence of active disease. In one patient, FDG-PET-CT carried out after completion of chemotherapy showed evidence of active disease and was given radiotherapy.

Conclusion:

FDG-PET-CT is a promising modality in deciding further management when there is discordance between the post-treatment CT scan and clinical condition of the patient with HL thus avoiding unnecessary chemotherapy/radiotherapy.

The role of FDG-PET scanning in assessing lymphoma in 2012

Positron emission tomography (PET) has a proven role in the assessment diffuse large B-cell lymphoma (DLBCL) and Hodgkin's lymphoma (HL). The clinical impact of PET carried out at the end of the patient's course of treatment is undeniable and recommendations must be followed in the interpretation of these examinations. PET is highly recommended as part of the initial investigations of these diseases because it can be used as a reference for the interpretation at treatment completion and allows disease spread to be assessed with greater sensitivity and specificity than when computed tomography (CT) is used. It seems to be certain that PET is useful for interim examinations too, in terms of assessing prognosis in DLBCL and HL, although its impact in terms of early changes to treatment is still to be determined. The criteria for interpreting the results of these early assessments are still evolving and the annual meetings in Menton, France, of groups of experts are leading towards a uniform interpretation method. In other types of lymphoma, PET can be useful for confirming local disease staging, especially in follicular lymphoma, and for guiding biopsy in patients with low-grade lymphoma that is suspicious for transformation into more aggressive disease. Several studies are in agreement that PET is valuable for assessing prognosis at treatment completion in FL and mantle cell lymphoma, but prospective studies are needed for this new indication to be validated.

Early interim FDG PET/CT prediction of treatment response and prognosis in pediatric Hodgkin disease-added value of low-dose CT

BACKGROUND

Interim 18F-FDG PET helps predict outcome and tailor treatment in adults with Hodgkin disease (HD).

OBJECTIVE

The purpose of this study was to assess predictive values of interim 18F-FDG PET/CT in children with HD and to define the potential added value to interim PET of low-dose CT.

MATERIALS AND METHODS

Children were prospectively enrolled August 2002-April 2007. PET/low-dose CT was performed at staging, after 2 cycles, at the end of treatment and during follow-up (mean 45 months). Treatment was unchanged regardless of interim results. PET and low-dose CT were read independently.

RESULTS

Of 34 enrolled children (ages 3-17 years), 27 achieved complete response, 4 had progressive disease and 3 had relapse. Interim PET alone had positive and negative predictive values of 67% and 89%, respectively. Interim low-dose CT alone had positive and negative predictive values of 35% and 100%, respectively. Interim PET/CT had positive and negative predictive values of 75% and 96%, respectively.

CONCLUSIONS

Early interim PET/CT was a good predictor of outcome. Integrated PET and low-dose CT improved the predictive value in children with HD.

Tailored strategies for radiation therapy in classical Hodgkin's lymphoma

Radiotherapeutic advances have contributed to the evolution of Hodgkin's lymphoma (HL) treatment paradigms. A reduction in radiation therapy (RT) field size and dose has the potential to significantly impact the therapeutic ratio by diminishing late toxicities while maintaining curability. Substantial progress in risk stratification has contributed to the development of tailored RT strategies which address both field design as well as dose. Technologic improvements have also enhanced the ability to adapt the RT technique to the individual patient. The refinement of the RT approach and its incorporation into current combined modality strategies in adult classical HL is the subject of ongoing investigation and is critically reviewed.

FDG-PET/CT based response-adapted treatment

It has been shown that [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) provides robust and reproducible data for early metabolic response assessment in various malignancies. This led to the initiation of several prospective multicenter trials in malignant lymphoma and adenocarcinoma of the esophagogastric junction, in order to investigate whether the use of PET-guided treatment individualization results in a survival benefit. In Hodgkin lymphoma and aggressive non-Hodgkin lymphoma, several trials are ongoing. Some studies aim to investigate the use of PET in early identification of metabolic non-responders in order to intensify treatment to improve survival. Other studies aim at reducing toxicity without adversely affecting cure rates by safely de-escalating therapy in metabolic responders. In solid tumors the first PET response-adjusted treatment trials have been realized in adenocarcinoma of the esophagogastric junction. These trials showed that patients with an early metabolic response to neoadjuvant chemotherapy benefit from this treatment, whereas metabolic non-responders should switch early to surgery, thus reducing the risk of tumor progression during chemotherapy and the risk of toxic death. The trials provide a model for designing response-guided treatment algorithms in other malignancies. PET-guided treatment algorithms are the promise of the near future; the choice of therapy, its intensity, and its duration will become better adjusted to the biology of the individual patient. Today's major challenge is to investigate the impact on patient outcome of personalized response-adapted treatment concepts.

Interim [(18)F]fluorodeoxyglucose positron emission tomography imaging in stage I-II non-bulky Hodgkin lymphoma: would using combined positron emission tomography and computed tomography criteria better predict response than each test alone?

Our objective was to validate the International Harmonization Project (IHP) positron emission tomography (PET) response criteria and correlate with the Deauville criteria and diagnostic computed tomography-based (dCT) lesion size changes. All patients were recruited prospectively to the Cancer and Leukemia Group B (CALGB) 50203 trial for the treatment of stage I-II, non-bulky Hodgkin lymphoma (HL). [(18)F]Fluorodeoxyglucose (FDG) PET and dCT were performed at baseline and after two doxorubicin, vinblastine and gemcitabine (AVG) cycles (PET-2, dCT-2) in 88 patients. IHP and Deauville criteria and percent decrease in the sum of the products of the perpendicular diameters (%SPPD) after two cycles were correlated with progression-free survival (PFS). After a median follow-up of 3.3 years, 23.9% of patients relapsed/progressed (3-year PFS 77%). By IHP, the 2-year PFS was 88% and 54% for PET-2 negative and positive groups, respectively (p = 0.0009). Similar results were obtained for Deauville criteria. In a univariate analysis, PET-2 predicted PFS better than %SPPD, and in a combinatorial analysis, in the PET-2 positive group, a negative dCT-2 increased PFS by 27-35%. However, some confidence intervals were large due to small sample sizes. In conclusion, IHP and Deauville criteria-based interpretation of PET-2 was strongly associated with 2-year PFS. The combined analysis of PET-2 with dCT-2 suggested a better predictive value for PFS compared to either test alone. Further studies are under way to confirm these findings.

Interim FDG-PET in Hodgkin lymphoma: a compass for a safe navigation in clinical trials?

Despite the rewarding results achieved in the treatment of Hodgkin lymphoma (HL), concerns have been raised regarding the long-term complications induced by therapy. Hence, the current challenge is to develop a new therapeutic strategy maintaining excellent patient outcome while reducing potentially life-threatening late adverse effects. Therefore, it would be beneficial to identify chemoresistant or refractory patients early during therapy for appropriate and timely escalation of treatment. Recently, compelling data have emerged on the prognostic role of interim [18F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) performed early during the course of treatment to predict ultimate outcome, even proving superior to conventional prognostic factors. Several ongoing prospective trials are exploring the feasibility of treatment de-escalation strategies in patients with a negative interim PET, as well as therapy escalation in advanced-stage HL patients who have a positive interim PET result. In this article, the published reports on the contribution of interim PET to the design of ongoing response-adapted clinical trials are reviewed. Moreover, some of the unresolved issues revolving around the suboptimal positive predictive value of interim PET are addressed with an emphasis on the interpretation criteria. A final remark on the appropriate use of interim PET is also provided.

[Importance of PET/CT in lymphoma diagnostics]

CLINICAL/METHODICAL ISSUE

Staging or re-staging of lymphomas using conventional imaging modalities is based on morphological changes, usually on the diameter of lesions. However, vitality of tumors cannot be evaluated.

STANDARD RADIOLOGICAL METHODS

In this context computed tomography (CT) has been used as a standard modality.

METHODICAL INNOVATIONS

Since the introduction of positron emission tomography (PET), evaluation of tumor vitality has become possible. Moreover PET/CT hybrid scanners were brought onto the market one decade ago.

PERFORMANCE

The fluorodeoxyglucose (FDG) PET/CT technique is now accepted as one of the most accurate modalities in the diagnosis of aggressive lymphomas due to a high FDG uptake (overall accuracy > 90%, sensitivity >90%). However, indolent lymphomas suffer from lower FDG uptake due to a moderate metabolic activity. After the introduction of PET/CT hybrid imaging the specificity of this diagnostic technique increased significantly compared to PET alone (from > 80% to > 90%). With the utilization of PET approximately 20% more lesions are detected when comparing to CT alone and in up to 15% of the patients this also results in a change of the therapeutic regime. As post-chemotherapy scar tissue usually persists for months, evaluation of vitality within residual bulks using FDG-PET can predict therapy response much earlier than CT, enabling therapy stratification. Other PET tracers apart from FDG have low impact in imaging of lymphomas and only the thymidine analogue fluorothymidine (FLT) is used in some cases for non-invasive measurement of proliferation.

ACHIEVEMENTS

Despite the capability of FDG-PET/CT there is no evidence that the improvement in diagnostics is translated into a better patient outcome and therefore warrants the high costs. False positive findings in PET can result in unnecessary treatment escalation with subsequent higher therapy-associated toxicity and costs.

PRACTICAL RECOMMENDATIONS

Some pitfalls can be avoided by scheduling PET scans carefully. As treatment-induced inflammation early after therapy can be misinterpreted as vital tumor tissue, it is recommended to wait at least 3 weeks between the last treatment cycle and the subsequent FDG-PET follow-up. Until the results of the prospective multicenter trials "PETAL" and "HD-18" become available, in Germany FDG-PET is only recommended generally for restaging Hodgkin's disease with a known rest bulk of  > 2.5 cm in justifiable individual cases or in clinical trials.

[Quantitative and qualitative evaluation of the interim PET/CT in lymphoma treatment in the prediction of complete metabolic response]

OBJECTIVE

To compare two different methods for the interpretation of interim PET/CT (PET/CT-i) in lymphomas, and to establish which one best predicts a complete metabolic response (CMR) in the PET/CT study at the end of treatment (PET/CT-et).

MATERIAL AND METHODS

Retrospective longitudinal analysis of the PET/CT studies for staging (PET/CT-s), PET/CT-i and PET/CT-et of 65 patients, 35 Hodgkin's lymphoma (HL) and 30 Non-HL. The PET/CT-i was performed between the second and fourth chemotherapy cycle. It was interpreted using two different criteria: qualitative criteria (5 point visual scale), semiquantitative criteria (percentage difference between the lesion with more SUVmax in the PET/CT-s and PET/CT-i). We analyzed the likelihood of obtaining a CMR in the PET/CT-et according to the results obtained on the PET/CT-i with these two criteria.

RESULTS

We obtained sensitivity (S), specificity (Sp), positive predictive values (PPV), negative predictive values (NPV) and likelihood ratio (LR) for the qualitative/semiquantitative method of 91%/80%, 76.2%/67%, 88.9%/83.3%, 80%/60.9% and 32%/7.8%, respectively, to predict a CMR in the PET/CT-et. There were no statistically significant differences between the LR of both methods (p=0.1942).

CONCLUSION

We found clear differences in S, Sp, PPV and NPV between both interpretation criteria for the PET/CT-i to predict a CMR in the PET/CT-et. Nevertheless, we cannot confirm the superiority of the qualitative method over the semiqualitative method for this purpose as no statistically significance differences were found in their LR in our study.

Reduced-intensity chemotherapy and PET-guided radiotherapy in patients with advanced stage Hodgkin's lymphoma (HD15 trial): a randomised, open-label, phase 3 non-inferiority trial

BACKGROUND

The intensity of chemotherapy and need for additional radiotherapy in patients with advanced stage Hodgkin's lymphoma has been unclear. We did a prospective randomised clinical trial comparing two reduced-intensity chemotherapy variants with our previous standard regimen. Chemotherapy was followed by PET-guided radiotherapy.

METHODS

In this parallel group, open-label, multicentre, non-inferiority trial (HD15), 2182 patients with newly diagnosed advanced stage Hodgkin's lymphoma aged 18-60 years were randomly assigned to receive either eight cycles of BEACOPP(escalated) (8×B(esc) group), six cycles of BEACOPP(escalated) (6×B(esc) group), or eight cycles of BEACOPP(14) (8×B(14) group). Randomisation (1:1:1) was done centrally by stratified minimisation. Non-inferiority of the primary endpoint, freedom from treatment failure, was assessed using repeated CIs for the hazard ratio (HR) according to the intention-to-treat principle. Patients with a persistent mass after chemotherapy measuring 2·5 cm or larger and positive on PET scan received additional radiotherapy with 30 Gy; the negative predictive value for tumour recurrence of PET at 12 months was an independent endpoint. This trial is registered with Current Controlled Trials, number ISRCTN32443041.

FINDINGS

Of the 2182 patients enrolled in the study, 2126 patients were included in the intention-to-treat analysis set, 705 in the 8×B(esc) group, 711 in the 6×B(esc) group, and 710 in the 8×B(14) group. Freedom from treatment failure was sequentially non-inferior for the 6×B(esc) and 8×B(14) groups as compared with 8×B(esc). 5-year freedom from treatment failure rates were 84·4% (97·5% CI 81·0-87·7) for the 8×B(esc) group, 89·3% (86·5-92·1) for 6×B(esc) group, and 85·4% (82·1-88·7) for the 8×B(14) group (97·5% CI for difference between 6×B(esc) and 8×B(esc) was 0·5-9·3). Overall survival in the three groups was 91·9%, 95·3%, and 94·5% respectively, and was significantly better with 6×B(esc) than with 8×B(esc) (97·5% CI 0·2-6·5). The 8×B(esc) group showed a higher mortality (7·5%) than the 6×B(esc) (4·6%) and 8×B(14) (5·2%) groups, mainly due to differences in treatment-related events (2·1%, 0·8%, and 0·8%, respectively) and secondary malignancies (1·8%, 0·7%, and 1·1%, respectively). The negative predictive value for PET at 12 months was 94·1% (95% CI 92·1-96·1); and 225 (11%) of 2126 patients received additional radiotherapy.

INTERPRETATION

Treatment with six cycles of BEACOPP(escalated) followed by PET-guided radiotherapy was more effective in terms of freedom from treatment failure and less toxic than eight cycles of the same chemotherapy regimen. Thus, six cycles of BEACOPP(escalated) should be the treatment of choice for advanced stage Hodgkin's lymphoma. PET done after chemotherapy can guide the need for additional radiotherapy in this setting.

FUNDING

Deutsche Krebshilfe and the Swiss Federal Government.

Doing more harm than good? Do systematic reviews of PET by health technology assessment agencies provide an appraisal of the evidence that is closer to the truth than the primary data supporting its use?

Health technology assessment (HTA) has the objective of providing individual patients, clinicians, and funding bodies with the highest-quality information on the net patient benefits and cost effectiveness of medical interventions. Founded on systematic reviews of the available evidence, HTA aims to reduce bias and thereby provide a more valid evaluation of the benefits of new medical interventions than the primary studies themselves. Competing with the traditional role of medical experts, HTA agencies have gained considerable influence over public opinion and policy. The fundamental tenets of evidence-based medicine mandate that this influence should be used first and foremost for the benefit of patients. Over nearly 2 decades, multiple HTA systematic reviews in many countries have discredited most or all of the evidence pertaining to the ability of PET to improve patient-important outcomes. These determinations have delayed, restricted, and, in many cases, prevented access to this technology, especially by cancer patients. HTA systematic review findings are very much at variance with the opinion of clinicians. Our scrutiny of these reviews, benchmarking them against the core values of science and evidence-based medicine, has revealed errors of fact, inappropriate exclusion of pertinent data, and injudicious appraisal of the clinical relevance of evidence, potentially introducing bias into these reviews and compromising the validity of their conclusions about the net patient benefits of PET. We believe that our findings mandate that the molecular imaging community actively engage institutionalized HTA agencies to ensure appropriate representation of our primary data and adherence to the highest principles of evidence-based medicine.

HIV-Associated Hodgkin's Lymphoma: Prognosis and Therapy in the Era of cART

Patients with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) are at increased risk for developing Hodgkin's lymphoma (HL), a risk that has not decreased despite the success of combination antiretroviral therapy (cART) in the modern era. HIV-associated HL (HIV-HL) differs from HL in non-HIV-infected patients in that it is nearly always associated with Epstein-Barr virus (EBV) and more often presents with high-risk features of advanced disease, systemic "B" symptoms, and extranodal involvement. Before the introduction of cART, patients with HIV-HL had lower response rates and worse outcomes than non-HIV-infected HL patients treated with conventional chemotherapy. The introduction of cART, however, has allowed for the delivery of full-dose and dose-intensive chemotherapy regimens with improved outcomes that approach those seen in non-HIV infected patients. Despite these significant advances, HIV-HL patients remain at increased risk for treatment-related toxicities and drug-drug interactions which require careful attention and supportive care to insure the safe administration of therapy. This paper will address the modern diagnosis, risk stratification, and therapy of HIV-associated HL.

PET in T-Cell Lymphoma

Most non-Hodgkin lymphomas (NHL) are of B-cell origin; only about 10% are T-cell or NK-cell lymphomas. The clinical features of T/NK-cell lymphomas differ from those of B-cell lymphomas: advanced stage and extranodal disease are more common and the prognosis is worse. Several studies have confirmed that 2-[fluorine-18]fluoro-2-deoxy-D-glucose (18FDG) uptake varies among different subtypes of lymphoma, a disparity that can be explained by the differences in histology, proliferation of tumor cells, and the ratio of viable tumor and reactive cells in the environment. These observations are based on investigation of B-cell lymphomas. Positron emission tomography (PET)/computed tomography (CT) was found to be useful both at staging and at measuring the therapeutic outcome after two to three cycles of chemotherapy (interim PET/CT). Several meta-analyses have confirmed the role of PET in evaluating the viability of the residual tumor mass after treatment. 18FDG-PET has been proved to have an excellent negative predictive value. Conversely, only a few studies have investigated the role of FDG-PET in T/NK-cell lymphomas. This paper summarizes the current information regarding the potential use of PET/CT in patients with T-cell lymphoma.