Early detection of relapse by whole-body positron emission tomography in the follow-up of patients with Hodgkin's disease

Use of FDG-PET to monitor response to chemotherapy and radiotherapy in patients with lymphomas

Lymphoma is a heterogeneous group of diseases with many curable subtypes. Primary treatment cures a significant proportion of, but not all, patients. Patients not achieving a complete remission with primary treatment, or those who relapse later, have a second chance of cure with high-dose chemotherapy and haematopoietic stem cell transplantation. Response assessment is therefore crucial in the management of lymphomas. FDG-PET has an emerging role in assessing response, both at the end of and during treatment. This article will review the current published evidence and offer some suggestions on future directions from a clinician's viewpoint.

Comparison of magnetic resonance imaging and (67)gallium scintigraphy in the evaluation of posttherapeutic residual mediastinal mass in the patients with Hodgkin's lymphoma

INTRODUCTION

Detection of residual disease following the completion of primary treatment in Hodgkin's lymphoma (HL) patients diagnosed with mediastinal tumor mass has an exceptional importance in the assessment of therapeutic response. Magnetic resonance imaging (MRI) and (67)gallium ((67)Ga) scintigraphy can be used to identify active tumor tissue in the mediastinal residuum.

AIMS

To evaluate: the accuracy of MRI and (67)Ga scintigraphy in the prediction of clinical HL relapse/progression; congruence of findings and the probability of mediastinal disease relapse/progression regarding to the detection of active/inactive tissue by both imaging methods.

MATERIALS AND METHODS

Thirty HL patients with abnormal mediastinal tissue following the completion of primary treatment were examined by MRI and (67)Ga scintigraphy. Positive findings were: high signal intensity on unenhanced T2-weighted images on MRI and the abnormal accumulation of gallium on scintigraphy or SPECT. These findings were compared with the clinical follow-up.

RESULTS

Sensitivity, specificity, accuracy, positive and negative predictive values were: 75.0%, 96.2%, 93.3%, 75.0%, 96.2% in MRI and 50.0%, 88.5%, 83.3%, 40.0%, 92.0% in (67)Ga scintigraphy. Discrepant results concerning the mediastinal tissue activity were found in 3 of 30 patients (10%). No statistically significant differences were found between both imaging methods in sensitivity, specificity and accuracy. Estimated 2-years progression free survival (PFS) for patients without and with active residual mediastinal tissue by MRI was 96% and 25% (p=0.0001), respectively. The probability of 2-years PFS in the cases with negative and positive findings on (67)Ga scintigraphy was 92% and 60% (p=0.026), respectively.

CONCLUSION

Although MRI showed better results than (67)Ga scintigraphy in the assessment of residual mediastinal tissue activity in HL patients after primary treatment, the difference between these methods was not statistically significant. Both methods could be included in the standard restaging protocol.

Utility of PET scans to predict disease relapse in pediatric patients with Hodgkin lymphoma

BACKGROUND

Positron emission tomography (PET) differentiates normal from abnormal cells based on metabolic activity. Numerous studies report that PET scan offers increased sensitivity, specificity and predictive values as compared to computed tomography (CT) in adult lymphoma patients.

PROCEDURE

Twenty-three consecutive pediatric Hodgkin lymphoma (HL) patients were evaluated with PET scan either at diagnosis or during treatment, then at therapy completion and in follow-up.

RESULTS

Twenty two of the 23 patients had a negative PET scan at the end of therapy; however, ten later developed a positive scan for a total of 11 (47.8%) patients with a positive post treatment PET scan. Six tissue biopsies were performed in five patients; four specimens were negative for disease and two confirmed HL relapse. Six patients were monitored clinically and remained asymptomatic; four had resolution of abnormalities on repeat PET while two had persistently positive, but stable PET scan findings and continue to be in remission at 11 and 40 months following treatment. Twelve (52.2%) patients of the original cohort have had consistently negative PET scans and have not relapsed.

CONCLUSIONS

PET is a sensitive (100%), but not a specific (57.1%) method for evaluating post-treatment pediatric HL patients with a strong negative predictive value (NPV; 100%), but poor positive predictive value (PPV; 18.2%). We do not recommend treatment decisions be based solely on PET scan results.

Revised Response Criteria for Malignant Lymphoma

Purpose

Standardized response criteria are needed to interpret and compare clinical trials and for approval of new therapeutic agents by regulatory agencies.

Methods

The International Working Group response criteria (Cheson et al, J Clin Oncol 17:1244, 1999) were widely adopted, but required reassessment because of identified limitations and the increased use of [18F]fluorodeoxyglucose-positron emission tomography (PET), immunohistochemistry (IHC), and flow cytometry. The International Harmonization Project was convened to provide updated recommendations.

Results

New guidelines are presented incorporating PET, IHC, and flow cytometry for definitions of response in non-Hodgkin's and Hodgkin's lymphoma. Standardized definitions of end points are provided.

Conclusion

We hope that these guidelines will be adopted widely by study groups, pharmaceutical and biotechnology companies, and regulatory agencies to facilitate the development of new and more effective therapies to improve the outcome of patients with lymphoma.

[Filling the thymic space after treatment of Hodgkin's disease: rebound or relapse]

We report the case of a 36-year-old women with Hodgkin's disease treated with polychemotherapy and bone marrow autograft. Progressive growth of a thymic mass suggested possible relapse four months after treatment withdrawal. This mass did not exhibit gallium-67 uptake but showed strong affinity for 18-FDG (SUV=6.8). Surgical biopsy ruled out recurrence of Hodgkin's disease of the thymus and led to the diagnosis of thymic rebound. The aspect of the thymic compartment returned to normal spontaneously at one year.

Predictive Role of Positron Emission Tomography in the Outcome of Patients with Follicular Lymphoma

PURPOSE

The purpose of this study was to evaluate the reliability of positron emission tomography (PET) in patients with follicular lymphoma (FL) after induction treatment.

PATIENTS AND METHODS

In all, 45 previously untreated patients with FL were studied with PET and computed tomography (CT) scans after chemotherapy induction treatment (fludarabine-containing regimens and CHOP [cyclophosphamide/doxorubicin/vincristine/prednisone] chemotherapy). Histopathologic analysis was performed when considered necessary.

RESULTS

After treatment, 4 of 5 patients (80%) who had CT-negative/PET-positive findings experienced relapse/progression, compared with only 1 of 22 patients (4.5%) in the CT-negative/PET-negative subset. Among the 18 patients with CT-positive findings, all 6 patients (100%) who had PET-positive findings experienced relapse or progression, compared with 1 of 12 patients (8.3%) who had PET-negative findings. The 2-year progression-free survival rates were 20% and 90% in the CT-negative/PET-positive and CT-positive/PET-negative subsets, respectively (P = 0.0031). During the follow-up, 2 patients, who presented a PET positivity with a negative CT scan, underwent a lymph node biopsy, which confirmed the presence of FL infiltration.

CONCLUSION

In patients with FL, persisting PET positivity is predictive of early disease progression, because it is still highly likely that patients with PET-negative findings will ultimately progress, but this has not yet been manifested during the period of observation.

Positron emission tomography/computed tomography in the management of Hodgkin's disease and non-Hodgkin's lymphoma

The incidence of Hodgkin's disease (HD) and Non-Hodgkin's lymphoma (NHL) is around 8% of all malignancies. Fortunately, HD and NHL are among the few malignancies that are potentially curable with current existing treatment modalities, even in advanced or recurrent disease. Accurate staging, early therapy monitoring, and posttreatment evaluation of lymphomas are important for optimum management of these patients. We reviewed the imaging findings of patients with histologically proved lymphoma who underwent staging positron emission tomography/computed tomography (PET/CT), early monitoring therapy PET/CT (after 3 cycles of chemotherapy), and posttreatment PET/CT. PET/CT imaging findings are shown. Utility of PET/CT in recognizing false-positive and false-negative cases of CT and PET alone is addressed. Pitfalls and diagnostic difficulties are analyzed. PET/CT is a new imaging technology that improves the evaluation of lymphoma. This review will help the reader to better understand the imaging findings and applications of PET/CT in the management of lymphoma.

Molecular Imaging of Proliferation in Malignant Lymphoma

We have determined the ability of positron emission tomography (PET) with the thymidine analogue 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) to detect manifestation sites of malignant lymphoma, to assess proliferative activity, and to differentiate aggressive from indolent tumors. In this prospective study, FLT-PET was done additionally to routine staging procedures in 34 patients with malignant lymphoma. Sixty minutes after i.v. injection of approximately 330 MBq FLT, emission and transmission scanning was done. Tracer uptake in lymphoma was evaluated semiquantitatively by calculation of standardized uptake values (SUV) and correlated to tumor grading and proliferation fraction as determined by Ki-67 immunohistochemistry. FLT-PET detected a total of 490 lesions compared with 420 lesions revealed by routine staging. In 11 patients with indolent lymphoma, mean FLT-SUV in biopsied lesions was 2.3 (range, 1.2-4.5). In 21 patients with aggressive lymphoma, a significantly higher FLT uptake was observed (mean FLT-SUV, 5.9; range, 3.2-9.2; P < 0.0001) and a cutoff value of SUV = 3 accurately discriminated between indolent and aggressive lymphoma. Linear regression analysis indicated significant correlation of FLT uptake in biopsied lesions and proliferation fraction (r = 0.84; P < 0.0001). In this clinical study, FLT-PET was suitable for imaging malignant lymphoma and noninvasive assessment of tumor grading. Due to specific imaging of proliferation, FLT may be a superior PET tracer for detection of malignant lymphoma in organs with high physiologic fluorodeoxyglucose uptake and early detection of progression to a more aggressive histology or potential transformation.

Routine use of PET scans after completion of therapy in pediatric Hodgkin disease results in a high false positive rate

PURPOSE

Fluoro-2-deoxy-D-glucose positron emission tomography scans are becoming standard of care in the evaluation of Hodgkin disease (HD). The frequency of false positive (FP) PET scans in pediatric HD after completion of therapy has not been well studied.

PATIENTS AND METHODS

All PET scan reports on pediatric HD patients at our institution between February 2000 and February 2005 were retrospectively reviewed. Scans were considered positive if the interpretation was most consistent with malignancy. FP results were determined by pathologic evaluation, resolution on scan, or absence of disease progression over at least 1 year without intervention.

RESULTS

We reviewed 255 PET scans on 47 patients, including 156 posttherapy scans on 34 patients. Positive predictive value for scans obtained during routine follow-up was 11%, with an FP rate of 16%. Identifiable etiologies of FP scans included: fibrosis, progressive transformation of germinal centers, abdominal wall hernia, appendicitis, thymus and HIV associated lymphadenopathy.

CONCLUSIONS

Routine PET scans after completion of therapy in pediatric HD patients have a low positive predictive value and a high FP rate. Prospective studies are needed to reduce the ambiguity of positive results. In the interim, positive PET scans after treatment should be interpreted cautiously and therapeutic decisions should not be made without histologic confirmation.

PET in lymphoma

This review attempts to discuss the role of positron emission tomography (PET) imaging for staging, treatment response and follow-up of patients with lymphoma. The pitfalls and impact of PET imaging on the clinical management are also addressed.

False-positive axillary lymph node on FDG-PET/CT scan resulting from immunization

An initial CT of a 59-year-old man with increasing back pain and weight loss showed lymphadenopathy in multiple nodal beds. A biopsy showed diffuse, large B-cell lymphoma (DLBCL). After initial chemotherapy, residual disease prompted an autologous stem cell transplant. After a follow-up FDG-PET/CT scan showed no FDG-avid disease, a subsequent study showed FDG uptake in a nonenlarged left axillary lymph node. Questioning elicited a recent immunization history. A follow-up PET/CT scan showed no uptake in this lymph node and no disease recurrence. Without this history, an unnecessary biopsy or treatment may have ensued. Methods to avoid such occurrences are discussed.

Unsuspected FDG–PET findings in the follow-up of patients with lymphoma

18F-Fluorodeoxyglucose-positron emission tomography (FDG-PET) plays an increasing role in the management of patients with lymphoma, for which it is successfully used for staging and treatment monitoring. We report seven patients with a history of lymphoma who presented a positive FDG-PET suggestive of lymphoma relapse and for which FDG-PET oriented biopsies revealed alternative diagnoses. Early in lymphoma follow-up, persistence of focal increased FDG activity corresponded to inflammatory or infectious lesions in two patients: one aspergillosis and one sarcoidosis. Later in the follow-up, five cases of secondary malignancies were identified (three lung cancers, one epidermoid carcinoma, and one villous tumor) in this particularly exposed population. The routine use of FDG PET to evaluate lymphoma significantly increases the probability of detecting unexpected diseases. These cases illustrate the potential pitfalls in PET follow-up. Because FDG is not lymphoma-specific, a relapse suspected only on FDG-PET imaging requires biopsy, as alternative diagnoses--infectious or malignant--are possible. Our data draws clinician's attention to potential false-positive FDG-PET findings, which may lead to therapeutic mistakes. Our data also suggests that FDG-PET might be a new imaging modality for long-term monitoring of late effects, especially second cancer occurrence.

Cost-effectiveness analysis of computerized tomography in the routine follow-up of patients after primary treatment for Hodgkin's disease

PURPOSE

To estimate the clinical benefits and cost effectiveness of computed tomography (CT) in the follow-up of patients with complete response (CR) after treatment for Hodgkin's disease (HD).

PATIENTS AND METHODS

We developed a decision-analytic model to evaluate follow-up strategies for two hypothetical cohorts of 25-year-old patients with stage I-II or stage III-IV HD, treated with doxorubicin, bleomycin, vinblastine, and dacarbazine-based chemotherapy with or without radiation therapy, respectively. We compared three strategies for observing asymptomatic patients after CR: routine annual CT for 10 years, annual CT for 5 years, or follow-up with non-CT modalities only. We used Markov models to calculate life expectancy, quality-adjusted life expectancy, and lifetime costs. Baseline probabilities, transition probabilities, and utilities were derived from published studies. Cost data were derived from the Medicare fee schedule and medical literature. We performed sensitivity analyses by varying baseline estimates.

RESULTS

Annual CT follow-up is associated with minimal survival benefit. With adjustments for quality of life, we found a decrement in quality-adjusted life expectancy for early-stage patients followed with CT compared with non-CT modalities. Sensitivity analyses showed annual CT for 5 years becomes more effective than non-CT follow-up if the specificity of CT is 80% or more or if the disutility associated with a false-positive CT result is less than 0.01 quality-adjusted life years (QALYs). For advanced-stage patients, annual CT for 5 years is associated with a very small quality-adjusted survival gain over non-CT follow-up with an incremental cost-effectiveness ratio of 9,042,300 dollars/QALY.

CONCLUSION

Our analysis suggests that routine CT should not be used in the surveillance of asymptomatic patients in CR after treatment for HD.

FDG-PET/CT predicts outcome in patients with aggressive non-Hodgkin’s lymphoma and Hodgkin’s disease

Early therapy response assessment with metabolic imaging is potentially useful to determine prognosis in aggressive lymphoma and, thus, can guide first-line therapy. Forty-eight patients with aggressive lymphoma [24 Hodgkin's disease (HD); 24 non-Hodgkin's lymphoma (NHL)] underwent fluoro-deoxyglucose positron emission tomography (FDG-PET) before chemotherapy (PET1) and at mid-treatment (PET2). Therapeutic response was evaluated using conventional methods at mid-treatment. PET2 results were related to event-free survival (EFS) and overall survival (OS) using Kaplan-Meier analyses. PET1 was positive in all patients. PET2 was negative in 38 patients (18 NHL-20 HD) and positive in 10 (6 NHL-4 HD). Of the PET-negative patients, 61 and 65% achieved complete remission, and only 50 and 25% of PET-positive patients, respectively, for NHL and HD, achieved complete remission. Significant associations were found between PET2 and EFS (p = 0.0006) and OS (p = 0.04) for NHL, and EFS (p < 0.0001) for HD (but not for OS, because no HD patient died). FDG-PET at mid-treatment can predict the outcome of patients with aggressive lymphoma and should be a useful tool to modify an ineffective therapy.

Is 3′-deoxy-3′-18F-fluorothymidine a better marker for tumour response than 18F-fluorodeoxyglucose?

3'-Deoxy-3'-(18)F-fluorothymidine (FLT) was developed in 1998 by Shields and co-workers because monitoring of treatment response would be facilitated by imaging agents able to provide measures of tissue and tumour proliferation. Since then, FLT metabolism has been clarified in more detail in cell culture and experimental animal tumour models and also in clinical studies. Recently, FLT has increasingly been used for the assessment of response to anticancer treatment, mainly in tumour xenograft SCID mouse models; in contrast, clinical data are scarce. In this article we briefly summarise the intermediary metabolism of FLT and its application as an anticancer treatment response probe. The potential value and limitations of FLT as a highly promising proliferation imaging probe and its use for monitoring of treatment response are discussed.

Positron emission tomography imaging for lymphoma

PURPOSE OF REVIEW

To review the current role and the limitations of F-fluorodeoxygenase positron emission tomography in the management of lymphoma, with a particular focus on studies published since January 2004.

RECENT FINDINGS

F-fluorodeoxygenase positron emission tomography should be routinely performed at the initial diagnosis of patients with suffering from Hodgkin's disease because it adds useful informations to conventional staging techniques. Residual F-fluorodeoxygenase uptake is an important prognostic factor after one or a few cycles of chemotherapy, but it is clearly too early to change patient treatment on the basis of F-fluorodeoxygenase positron emission tomography results. F-fluorodeoxygenase positron emission tomography is the best noninvasive imaging technique after treatment; however, it is always indicated to correlate positron emission tomography findings with clinical data, other imaging modalities, a biopsy, or all three to reduce the risk of false positive results. There are some concerns about the positive predictive value of positron emission tomography after treatment, especially in childhood lymphoma. Clinicians should be aware of positron emission tomography findings in specific clinical conditions in this patient population. F-fluorodeoxygenase positron emission tomography combined with computed tomography offers advantages over the two used separately and read side by side. It may be particularly useful for the planning of radiation therapy or for the planning of a surgical biopsy. Several studies have shown that F-fluorodeoxygenase positron emission tomography is definitively superior to Ga scintigraphy. New radiotracers such as F-fluorothymidine may be useful for the noninvasive assessment of proliferation in vivo.

SUMMARY

F-fluorodeoxygenase positron emission tomography has become the most important nuclear medicine imaging modality in the field of lymphoma. It should be routinely used in the treatment of lymphoma patients.

Utility of FDG-PET/CT in follow-up of children treated for Hodgkin and non-Hodgkin lymphoma

Positron emission tomography using F-flurodeoxyglucose (FDG-PET) is considered an excellent tool for staging and monitoring disease status in adults with lymphoma. We retrospectively reviewed results of PET/CT and diagnostic computed tomography (CT) scans performed during follow-up after completion of therapy in 41 children <18 years of age with Hodgkin lymphoma and non-Hodgkin lymphoma. PET/CT scan with uptake greater than that of the liver was considered positive. Uptake that increased over the background but less than in the liver was equivocal. Clinical outcomes were obtained from medical records. Thirteen (32%) had a positive PET/CT scan and an equal number had equivocal scans in a median follow-up of 2.3 years. Diagnostic CT scans revealed new findings in 13 (32%) and persistent abnormalities in 21 (51%) of the children. Five children developed recurrent disease, and one developed a second cancer. No children with equivocal positivity developed recurrent disease. PET/CT scan was 95% sensitive, with a positive predictive value (PPV) of 53%. Diagnostic CT was 79% sensitive, with a PPV of 52%. We conclude that a negative PET/CT scan during routine follow-up for lymphoma in children strongly suggests absence of recurrence but a positive PET/CT and diagnostic CT scans have low PPV and should be interpreted with caution in this setting.

Utility of positron emission tomography (PET) scanning in managing patients with Hodgkin lymphoma

Use of positron emission tomography (PET) or PET/ computed tomography (CT) in Hodgkin lymphoma (HL) continues to expand worldwide. PET is currently widely utilized for response assessment after completion of therapy and, to a lesser extent, for pretreatment staging and assessment of response during therapy (therapy monitoring). In pretreatment staging, PET cannot replace CT or bone marrow biopsy (BMB); however, it can provide complementary information to both CT and BMB, potentially resulting in a modification of disease stage (usually upstaging) in about 15-20% of patients with impact on management in about 5-15%. PET for response assessment at the conclusion of treatment is substantially more accurate than CT because of its ability to distinguish between viable tumor and necrosis or fibrosis in posttherapy residual mass (es) that are present in about two-thirds of patients with HL without any other clinical or biochemical evidence of disease. PET, therefore, provides more accurate response classifications compared with CT-based assessment. The role of PET for therapy monitoring is still evolving but may prove to be the most exciting with potentially high impact on patient management and outcome. PET evaluation during therapy appears to be at least as accurate for predicting patient outcome as evaluation after completion of therapy and its use is clearly justified if the purpose is to provide an early and yet accurate assessment of response with the clear intent of tailoring therapy according to the information provided by the scan. The role of PET scanning for post-therapy surveillance without clinical, biochemical or radiographic evidence of disease remains controversial, primarily because of the potential for a disproportionate fraction of false-positive findings, potentially resulting in increasing cost without proven benefit from earlier PET detection of disease compared to standard surveillance methods. Large prospective studies are therefore needed to determine whether routine surveillance by PET is both cost-effective and whether it results in meaningful changes in patient management and/or outcome.

Value of [18F]Fluorodeoxyglucose–Positron Emission Tomography in Managing Adults with Aggressive Non-Hodgkin's Lymphoma

An increased glucose metabolic rate is observed with various degrees of intensity in different subtypes of aggressive lymphomas. [(18)F]Fluorodeoxyglucose (FDG)-positron emission tomography (PET; FDG-PET) allows functional imaging of this phenomenon through 3-dimensional tomographic slices, which are now easily fused with computed tomography (CT) images. [(18)F]Fluorodeoxyglucose-PET staging appears superior to conventional staging modalities for detecting nodal and extranodal lymphoma. When performed after first-line chemotherapy, FDG-PET is more efficient than CT and conventional diagnostic methods to predict the disease outcome. Some studies have reported that the relapse rate is 100% in patients with positive PET findings after treatment and 17% in patients with negative PET findings. This imaging modality can also assess early response after 1-2 cycles of chemotherapy, thus identifying responders from patients whose cancer will fail to respond to first-line therapy or will relapse shortly after having exhibited a partial or complete remission. [(18)F]Fluorodeoxyglucose-PET also seems useful for an accurate selection of patients who will benefit from highly intensive treatment.

Intense 18-fluorodeoxyglucose uptake by the thymus on PET scan does not necessarily herald recurrence of thyroid carcinoma

This is the first report of intense fluorodeoxyglucose positron emission tomography (FDG-PET) uptake secondary to thymic hyperplasia during follow-up for thyroid carcinoma. A 36-yr-old woman underwent thyroidectomy for a papillary carcinoma measuring 4 cm in diameter. After two doses of radioiodine, thyroglobulin (Tg) remained detectable following recombinant human TSH (rhTSH) stimulation. A whole body scan (WBS) was negative. On computed tomography (CT) scan, a slightly lobulated thymus was visualized. PET scan showed intense thymic uptake. Following resection, anatomo-pathological analysis showed homogenous hyperplastic thymic gland without neoplastic cells. Two months later, under levothyroxin (L-T4) substitution, Tg was no longer detectable and PET scanning did not show any 18-FDG uptake. This observation suggests that thymic FDG uptake does not necessarily herald recurrence of thyroid carcinoma and must be interpreted with caution in such a setting. Other conditions associated with abnormal uptake by hyperplastic thymus must also be envisaged.

MRI and PET in monitoring response in lymphoma

The potential of FDG-PET and MRI in monitoring response to treatment in lymphoma is reviewed. Both FDG-PET and MRI can provide whole body imaging. Both also share the advantage of combining functional and anatomical information. At present, hybrid FDG-PET and MDCT is the best technique for monitoring response to treatment, especially early response to treatment. Early assessment of response to treatment has the potential to tailor therapy. MR imaging is useful especially in assessing bone marrow and central nervous system involvement.

Role of active follow-up for early diagnosis of relapse after elective end of therapies

OBJECTIVE

To evaluate the role of active follow-up for the detection of relapses occurring after completion of therapy in children with cancer.

METHODS

The clinical records of all children who had a cancer relapse more than 3 months after the end of therapies in the period 1985-2000 were reviewed. Relapses were defined "diagnosed at a scheduled visit" or "at an unscheduled visit" based upon how the visit that lead to the suspected diagnosis was scheduled. Information was collected on how the first suspicion of relapse was made. Survival after relapse was calculated, by type of visit and tumor type.

RESULTS

Among 739 children who completed therapy for a malignant tumor in first complete remission (CR), 101 relapses [74 after solid tumors (ST), 27 after leukemia/lymphoma (L)] occurred after a median time of 12 months (range 3-87). Fifty-one (50.5%) first relapses were diagnosed during a visit scheduled because of symptoms (36 ST, 15 L), and 50 relapses (49.5%) at a regularly scheduled visit (38 ST, 12 L). Overall, 75% of relapses were first suspected on clinical basis, 16% via imaging, and only 9% via lab tests. Survival more than 10 years from first relapse was 25.7% (SE: 0.05%), with no significant differences between relapses diagnosed at a scheduled visit (20.5%), or at an unscheduled visit (32.1%; P = 0.826). Children with L had a better overall survival (OS, 70.6%) as compared to those with ST (9.2%, P < 0.001), probably because of a more extensive use of stem cell transplantation (SCT) as part of the salvage regimens.

CONCLUSIONS

Scheduled follow-up programs failed to detect relapses in 50% of cases presented here. Survival after relapse is not affected by whether relapse was detected at a scheduled or an unscheduled visit.

A metaanalysis of 18F-2-deoxy-2-fluoro-D-glucose positron emission tomography in the staging and restaging of patients with lymphoma

BACKGROUND

In recent years, the use of positron emission tomography (PET) has become widespread for the staging and follow-up of several malignancies. In the current study, the authors conducted a metaanalysis of the published literature to evaluate the diagnostic performance of 18F-2-deoxy-2-fluoro-D-glucose PET (FDG-PET) in the staging of patients with lymphoma.

METHODS

The authors conducted a systematic MEDLINE search of articles published between January 1995 and June 2004. Studies that evaluated FDG-PET with a dedicated camera and that reported sufficient data to permit the calculation of sensitivity and specificity were included in the analysis. Two reviewers independently reviewed the eligibility of the studies and abstracted data (sample population; characteristics of FDG-PET; and the number of true-positive results, true-negative results, false-positive results, and false-negative results). The authors estimated the pooled sensitivity, false-positive rate, and maximum joint sensitivity and specificity.

RESULTS

Twenty studies were eligible for the metaanalysis. Fourteen studies included patient-based data, comprising a sample size of 854 subjects, and 7 studies included lesion-based data, totaling 3658 lesions. Among those studies with patient-based data, the median sensitivity was 90.3% and the median specificity was 91.1%. The pooled sensitivity was 90.9% (95% confidence interval [95% CI], 88.0-93.4) and the pooled false-positive rate was 10.3% (95% CI, 7.4-13.8). The maximum joint sensitivity and specificity was 87.8% (95% CI, 85.0-90.7). The pooled sensitivity and false-positive rate appeared to be higher in patients with Hodgkin disease compared with those with non-Hodgkin lymphoma.

CONCLUSIONS

The results of the current study indicate that FDG-PET is a valuable tool for the staging and restaging of patients with lymphoma; showing a high positivity and specifity. Clinicians may consider adding FDG-PET to the staging workup of patients with lymphoma.

Evaluation of Therapy for Lymphoma

Positron emission tomography (PET) using (18)F-fluorodeoxyglucose ((18)F-FDG) is the best noninvasive imaging technique for to assess response in patients suffering from lymphoma. Early response evaluation ("interim PET") after one, a few cycles, or at midtreatment can predict response, progression-free survival, and overall survival. We calculated from data of 7 studies an overall sensitivity to predict treatment failure of 79%, a specificity of 92%, a positive predictive value (PPV) of 90%, a negative predictive value (NPV) of 81%, and an accuracy of 85%. Although it is not yet indicated to change patient management based on residual (18)F-FDG uptake on interim scan in chemotherapy-sensitive patients, prospective studies evaluating the role of an interim PET in patient management clearly are warranted. (18)F-FDG PET also has an important prognostic role in relapsing patients after reinduction chemotherapy before high-dose chemotherapy (HCT) followed by autologous stem cell transplantation (ASCT). However, all chemotherapy-sensitive patients remain candidates for HCT followed by ASCT, even if (18)F-FDG PET showed residual (18)F-FDG uptake. We calculated from data of 3 studies an overestimated risk of relapse in 16% of all PET-positive patients. Some patients with residual (18)F-FDG uptake will have a good outcome after HCT followed by ASCT. (18)F-FDG PET is the imaging technique of choice for end-of-treatment evaluation. However, (18)F-FDG is not specific for tumoral tissue. Active inflammatory lesions and infectious processes can be falsely interpreted as malignant residual cells. However, a negative (18)F-FDG PET cannot exclude minimal residual disease. Consequently, it is always indicated to correlate PET findings with clinical data, other imaging modalities, and/or a biopsy. We calculated, from data of 17 studies in end-of-treatment evaluation, a sensitivity of 76%, a specificity of 94%, a PPV of 82%, a NPV 92%, and an accuracy of 89%.

FDG-PET in the management of germ cell tumor

Germ cell tumor is the most common malignancy in young men. The cure rate of these patients has tremendously increased in the cisplatin era, and recent results have indicated that the management of patients with GCT is still improving. The use of FDG-PET in the management of patients with GCT has been recently investigated. This report attempts to comprehensively review new advances and delineate the potential applications of FDG-PET in GCT.

Contribution of PET imaging to the initial staging and prognosis of patients with Hodgkin's disease

BACKGROUND

Positron emission tomographic (PET) scanning utilizing [18F]fluorodeoxyglucose (FDG) is a new method of tumor imaging based on the increased glucose metabolic activity of malignant tumors. In Hodgkin's disease (HD), PET has proven value for the evaluation of residual masses following treatment and for the early diagnosis of relapse. In the initial staging of HD, PET frequently shows a higher stage than conventional methods (upstaging by PET). In the present study, we evaluated the frequency of stage changes by PET in a multicenter setting and determined its prognostic relevance.

PATIENTS AND METHODS

A total of 73 patients with newly diagnosed HD were staged with both conventional methods and whole-body PET scanning. All histological types and stages were represented. The median time of follow-up after the initial diagnosis was 25 months (range 1 month to 5 years). The response to treatment was determined by standard clinical and diagnostic criteria. For the purpose of this analysis, data from a PET center associated with a university medical center and a PET center associated with a group oncology practice were combined.

RESULTS

A total of 21 patients (28.8%) were upstaged by PET compared with conventional methods. In two cases (2.7%), a lower stage was suggested by PET scanning. With one possible exception, the upstaging had no obvious clinical or biological correlate. Among 12 patients in stage I (A + B) by conventional methods, seven were upstaged by PET (58.3%), four to stage II, one to stage III and two to stage IV. Among 42 patients in stage II, eight were upstaged by PET (19.0%), six to stage III and two to stage IV. Among 12 patients in stage III, six (50%) were upstaged to stage IV by PET. If only early-stage patients and major changes are considered (stages IA-IIB to III or IV), among 49, 10 were upstaged to III or IV, whereas in 39 staging was unchanged following PET. In the former group, three relapsed or were refractory compared with none in the latter group (P<0.006). In advanced stage patients (IIIA or IIIB) a trend toward treatment failure was apparent in patients who were upstaged by PET.

CONCLUSIONS

PET scanning is an interesting new modality for the accurate staging of patients with HD and frequently shows a higher stage than conventional methods. PET should be performed at initial diagnosis and should be included in prospective studies of patients with HD. Upstaging by PET may represent a risk factor for a more advanced stage or a biologically more aggressive tumor. Patients with early-stage disease as identified by conventional methods have a significant risk of treatment failure if a more advanced stage is indicated by PET. At present, major stage changes suggested by PET imaging should be confirmed by an independent diagnostic method.

Use of 18F-FDG positron emission tomography following allogeneic transplantation to guide adoptive immunotherapy with donor lymphocyte infusions

Fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) provides valuable prognostic information in the management of lymphoma patients. However, the utility of (18)F-FDG PET following allografting is unclear. We analysed the use of (18)F-FDG PET after allogeneic reduced-intensity transplantation (RIT) performed in our institution. Between June 1998 and January 2002, 55 patients underwent RIT for either Hodgkin or non-Hodgkin lymphoma. At least one (18)F-FDG PET scan was performed during the post-transplant period (median five studies) in 15 (27.2%) of these 55 patients. PET scans were performed after re-staging computed tomography (CT) and were categorised depending on (18)F-FDG uptake. The first PET scan was informative in 11 of 15 patients (73%) and influenced the administration of donor lymphocyte infusions (DLI) in nine: leading to earlier DLI administration in two patients, earlier dose escalation in one, withholding of DLI administration in five and dose reduction in one. In addition, subsequent monitoring with (18)F-FDG PET scans documented a graft-versus-lymphoma effect in five patients (median post-DLI follow-up 33 months, range 13-36 months). These preliminary data suggest that (18)F-FDG PET has a role in guiding DLI administration and monitoring the immunotherapeutic effect in patients after allogeneic transplantation. This retrospective pilot study forms the basis for a prospective study to clarify the utility of (18)F-FDG PET/CT in these patients.

FDG PET in the Evaluation of Treatment for Lymphoma: Clinical Usefulness and Pitfalls

Positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) may play an important role in the evaluation and management of malignant lymphoma. FDG uptake is predictive of therapeutic response during the course of treatment. After completion of chemotherapy, residual abnormalities representing either residual tumor or necrotic or fibrotic tissue are not uncommon, and FDG PET may be more accurate than computed tomography (CT) or magnetic resonance imaging in assessing residual disease and identifying patients who require more intense treatment. However, posttreatment FDG PET does not help exclude the presence of minimal residual disease, which may lead to disease relapse. Furthermore, FDG is not a tumor-specific substance, and increased accumulation may be seen in a variety of benign entities and scenarios (eg, infection, drug toxicity, granulocyte colony-stimulating factor therapy, radiation therapy, physiologic activity, postoperative or postbiopsy changes, fracture, degenerative change, injection leakage), which may yield false-positive findings. Nevertheless, recognition of these entities and correlation of FDG PET findings with clinical and other radiologic findings-especially those at combined PET and CT or PET-CT fusion imaging-allows improved diagnostic accuracy. If the interpretation of positive findings is exceptionally difficult, short-term follow-up may be helpful.

Utility of fluorodeoxyglucose-PET imaging in the management of patients with Hodgkin's and non-Hodgkin's lymphomas

FDG-PET imaging has a number of advantages in the management of patients with lymphoma. PET shows a functional metabolic status and gives quantitative information. In addition, PET provides whole-body images that give a comprehensive assessment of disease extent during the staging and followup. Based on the present literature, FDG-PET is at least equivalent to CT for the initial staging of lymphomas. The impact of new technologies of combined PET/CT and fast-scanning CT with contrast has yet to be evaluated in the management of lymphoma patients, however. At this point, FDG-PET and CT must be considered as giving complementary staging information. FDG-PET also has high diagnostic accuracy for restaging lymphoma after initial treatment. FDG-PET has shown high accuracy in the early prediction of response to chemotherapy and in the evaluation of residual masses after chemotherapy or radiation therapy. Therefore, PET is likely to play a major role in tailoring the intensity of the treatment to the individual patient. A pretreatment FDG-PET study is essential for accurate assessment of residual masses and early monitoring of response to the treatment. In addition, a baseline PET scan will help detect relapse or residual disease, because relapse occurs most often in the region of previous disease.

FDG-PET in the clinical management of Hodgkin lymphoma

Positron emission tomography (PET) is a molecular functional imaging technique that provides qualitative and quantitative information about the localization and activity of pathophysiological processes. The most commonly used tracer for oncological purposes is 2-[18F]fluoro-2-deoxy-d-glucose (FDG). FDG-PET has within recent years become the most important nuclear medicine imaging modality in the management of lymphoma. This review summarizes the data published so far concerning the value of FDG-PET in staging, treatment monitoring, therapy planning, and follow-up of Hodgkin lymphoma (HL). FDG-PET detects more disease sites and involved organs than conventional staging procedures including computerized tomography (CT) and has a large influence on staging. FDG-PET during and after therapy appears to provide considerable prognostic information. However, the impact on patient outcome is not clear since no controlled trials are conducted and follow-up periods are generally short. The value of dual-modality PET/CT and its potential role in the radiotherapy planning is discussed.

18F-FDG PET in children with lymphomas

PURPOSE

The aim of this study was to retrospectively evaluate the performance of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) in children with lymphomas, at various stages of their disease.

METHODS

Twenty-eight children (mean age 12.5 years, 14 girls, 14 boys) with Hodgkin's disease (HD, n=17) or non-Hodgkin's lymphoma (NHL, n=11) were evaluated. Patients were investigated at initial staging (n=19), early in the course of treatment (n=19), at the end of treatment (n=16) and during long-term follow-up (n=19). A total of 113 whole-body PET studies were performed on dedicated scanners. PET results were compared with the results of conventional methods (CMs) such as physical examination, laboratory studies, chest X-rays, computed tomography, magnetic resonance imaging, ultrasonography and bone scan when available.

RESULTS

At initial evaluation (group 1), PET changed the disease stage and treatment in 10.5% of the cases. In early evaluation of the response to treatment (group 2), PET failed to predict two relapses and one incomplete response to treatment. In this group, however, PET did not show any false positive results. There were only 4/75 false positive results for PET among patients studied at the end of treatment (group 3, specificity 94%) or during the systematic follow-up (group 4, specificity 95%), as compared with 27/75 for CMs (specificity 54% and 66%, respectively).

CONCLUSION

18F-FDG-PET is a useful tool for evaluating children with lymphomas. Large prospective studies are needed to appreciate its real impact on patient management.

The role of PET imaging in lymphoma

Positron emission tomography using fluorine-18 (FDG-PET) is increasingly used in the staging and follow-up of malignant lymphomas, although its precise role has not yet been determined. This review considers the results reported at the different stages in the disease history and separately considers the major histological subtypes. Attention is given to the situations in which PET scanning is most likely to influence management. Finally, this review discusses ongoing developments in PET scanning with improved resolution and different radiolabelled tracers.

Positron emission tomography in the evaluation of lymphoma

Positron emission tomography (PET) using (18)F-fluoro-deoxyglucose (FDG) has emerged in recent years as an important tool for the evaluation of lymphoma patients during their course of disease. At diagnosis, FDG imaging is capable of detecting nodal and extra nodal sites of disease and provides accurate staging. FDG-PET is superior to computed tomography, during and at the end of first-line treatment or salvage therapeutic regimens, as a tool for monitoring therapeutic response. PET enables the differential diagnosis of residual viable tumor versus a remnant fibrotic or necrotic mass. PET also provides prognostic data of high clinical significance for both Hodgkin's disease and non-Hodgkin's lymphoma. Results of this metabolic imaging modality, interpreted in view of the pretherapy risk profile of the individual patient, are predictive of the immediate success of a certain therapeutic strategy, as well as of overall and disease-free survival. PET appears to play also an important role in the detection of lymphoma relapse. Data comparing (67)Gallium scintigraphy and FDG-PET indicate the latter as the functional imaging modality of choice for assessment of lymphoma patients. Preliminary studies show an additional value of fused PET/computed tomography imaging for further improved diagnosis, staging and definition of status of lymphoma.

Pitfalls and artifacts in 18FDG PET and PET/CT oncologic imaging

It is estimated that in excess of one million positron emission tomography (PET) scans are performed each year and PET can now truly be regarded as a routine imaging procedure in clinical management. Many potential pitfalls and artifacts have previously been described with (18)F-fluorodeoxyglucose PET imaging, but more continue to become apparent as worldwide experience increases. In addition, the advent of combined PET/CT scanners in clinical imaging practice has brought their own specific pitfalls and artifacts. It is essential that we learn these potential pitfalls so that patients can be optimally prepared for their scans and that accurate interpretation can be made.

Part II: Hodgkin's lymphoma—diagnosis and treatment

The outcome of patients with all stages of Hodgkin's lymphoma has improved dramatically over the past few decades. This is mainly due to the use of risk-adapted therapies using intensive polychemotherapeutic regimens in combination with other modalities. Patients with early favourable or unfavourable (intermediate) stage disease receive two or four cycles of chemotherapy, respectively, followed by involved-field radiotherapy (20-30Gy). Advanced stage Hodgkin's lymphoma is treated more aggressively using six to eight cycles of chemotherapy but the effectiveness of consolidative radiotherapy for patients who show a complete response after chemotherapy alone is still unknown. The main challenge in the near future will be the development of strategies that decrease late morbidity and mortality but retain the same efficacy of current regimens. In this paper we review current diagnostic techniques and management strategies used to treat Hodgkin's lymphoma, and the range of new modalities being used to improve long-term outcome and patient quality of life.

Hodgkin's lymphoma: evolving concepts with implications for practice

Hodgkin's lymphoma is a unique neoplasm of B lymphocytes. Recent data provide new understandings of the pathogenesis and options for staging and therapy of the disease. Three specific topics are addressed in this chapter. In Section I, Dr. Richard Ambinder reviews implications of the relationship of Epstein-Barr virus (EBV) and Hodgkin's lymphoma. This relation includes varying geographic epidemiologic associations, including varying associations with the clinical syndrome of infectious mononucleosis. There are plausible mechanisms, including processes initiated by viral proteins, by which EBV might lead to tumorigenesis. These mechanisms include promotion of genetic instability and alteration of normal processes of apoptosis. In addition to an epidemiologic association and potential role in pathogenesis, viral antigens may pose theoretical targets for anti-cancer therapies, including vaccination. In Section II, Dr. Sigrid Stroobants describes the potential role of positron emission tomographic (PET) scanning. By assessing differences in the metabolic activities of cancer cells, PET scanning may be superior to computerized tomographic scanning, which is limited to showing structural anatomical abnormalities. In patients with Hodgkin's and non-Hodgkin's lymphoma, PET scanning has been tested as an initial staging tool, to assess the rate of therapeutic response from a prognostic perspective, and to differentiate residual tumor from fibrotic masses in patients who have completed therapy. Particularly in assessing the nature of a residual mass seen with other post-therapeutic imaging modalities, PET scanning may provide unique information; very high negative predictive values have been reported. However, before this technology can be recommended for incorporation into standard management, properly conducted prospective trials are required to better evaluate the clinical utility of PET with respect to eventual patient outcomes. In Section III, Dr. Ralph Meyer reviews current data regarding the management of patients with limited-stage Hodgkin's lymphoma. Over the past decade, standard treatment has evolved to consist of combined-modality therapy that includes an abbreviated course of chemotherapy and involved-field radiation. As this therapy continues to include radiation therapy, patients will remain at risk of long-term toxicities that include the development of second cancers and cardiovascular events. These "late-effects" now account for more deaths than those attributed to progressive Hodgkin's lymphoma. Comparative data testing the role of chemotherapy alone are now available and demonstrate that omission of radiation therapy results in small but statistically significant reduction in disease control, but no detectable differences in overall survival. Further follow-up will clarify whether chemotherapy alone is the preferred treatment option; at present patients should be informed of the trade-offs involved in choosing between this option and combined modality therapy.

PET Scans in the Staging of Lymphoma: Current Status

Positron emission tomography (PET) is a novel functional imaging technique that provides several inherent advantages over conventional nuclear scintigraphy. Several studies have suggested a role for PET using the positron emitter fluorine-18 in the diagnosis and follow-up of patients with lymphoma. This review summarizes the existing data evaluating the role of 2-fluoro-2-deoxy-D-glucose (FDG)-PET in both the staging and follow-up of patients with lymphoma. Most studies of PET involve patients with either Hodgkin's disease or diffuse large B-cell non-Hodgkin's lymphoma. PET detects more disease sites above and below the diaphragm on staging of lymphoma than gallium scintigraphy and may have particular utility in the evaluation of the spleen. Moreover, persistently positive PET scans during and after chemotherapy appear to have a high sensitivity for predicting subsequent relapse. A negative PET scan at the end of therapy provides very favorable prognostic information. Persistently positive PET scans at the end of therapy warrant close follow-up or additional diagnostic procedures, since some of those patients may remain in prolonged remission. Clearly, additional studies, including prospective blinded trials and cost-effectiveness analyses, are warranted to determine which subsets of patients with lymphoma ultimately will benefit from this modality.

PET scan imaging in oncology

With the emergence of positron emission tomography (PET) from research laboratories into routine clinical use, it is important to redefine the most appropriate use of each imaging technique. The aim of this review article is to show the potential of PET in oncology. We discuss the most promising indications and the perspectives for the future. We will also point out the shortcomings and the important questions to be answered before fully considering PET as a necessary tool in the day-to-day practice of oncology. Although many studies have documented the high accuracy of 18F-FDG PET for the detection and staging of malignant tumours and for the monitoring of therapy results in these patients, it is very important to assess the impact of the technique on patient outcome and to show cost-effectiveness from the societal viewpoint.