Efficacy of routine surveillance with positron emission tomography/computed tomography in aggressive non-Hodgkin lymphoma in complete remission: status in a single center

Clinical Utility of Routine Postoperative Imaging in Spinal Fusion Surgery: A Systematic Review

OBJECTIVE

Following spinal fusion surgery, routine imaging is often obtained in all patients regardless of clinical presentation. Such routine imaging may include x-ray, computed tomography, or magnetic resonance imaging studies in both the immediate postoperative period and after discharge. The clinical utility of this practice is questionable. Our goal is to assess the existing literature for evidence of impact on clinical care from routine radiographic surveillance following spinal fusion.

METHODS

A systematic search of Embase, Scopus, PubMed, Cochrane, and Ovid databases was performed for studies investigating postoperative imaging following spinal fusion surgery. Studies were analyzed for imaging findings and rates of change in management due to imaging.

RESULTS

In total, the review identified 9 studies that separated data by unique patient or by unique clinic visits. The 4 studies reporting per-patient data totaled 475 patients with 328 (69%) receiving routine imaging. Among these, 28 (8.5%) patients had abnormal routine findings with no patients having a change to their clinical course. Of the 5 studies that reported clinic visit data, 3119 patient visits were included with 2365 (76%) clinic visits accompanied by imaging. Across these 5 studies, 146 (6.2%) visits noted abnormal imaging with only 12 (0.5%) subsequent management changes.

CONCLUSIONS

Our analysis found that routine imaging after spinal fusion surgery had no direct benefit on clinical management. The utility of baseline imaging for long-term comparison and medicolegal concerns were not studied and remain up to the provider's judgment. Further research is necessary to identify optimal imaging criteria following spinal fusion surgery.

Surveillance imaging during first remission in follicular lymphoma does not impact overall survival

BACKGROUND

Although many patients with follicular lymphoma (FL) undergo routine radiographic surveillance during their first remission, no consensus exists on the modality, duration, frequency, or need for routine imaging studies. The authors retrospectively examined the effect of surveillance imaging on relapse detection and overall survival (OS) in patients with FL.

METHODS

Patients with newly diagnosed FL who had a response to induction therapy were identified from the Lymphoid Malignancies Enterprise Architecture Database (LEAD) at Emory University and from the Molecular Epidemiology Resource (MER) of the University of Iowa/Mayo Clinic. Patients were evaluated for both relapse and method of relapse detection (ie, clinical concerns vs radiologic detection through surveillance imaging in an asymptomatic patient).

RESULTS

Of 148 patients in the LEAD cohort, 55 (37%) relapsed, and the majority (n = 35; 64%) of relapses were detected clinically. In the MER cohort, 63 of 177 relapses (54%) were detected clinically. There was no significant difference in OS from the date of diagnosis between the 2 methods of relapse detection in the LEAD (hazard ratio [HR], 0.61; 95% CI, 0.13-2.94; P = .54) and MER (HR, 1.02; 95% CI, 0.47-2.21; P = .96) cohorts. Similarly, there was no significant difference in OS from the date of relapse between the 2 methods of relapse detection in the LEAD (HR, 0.47; 95% CI, 0.10-2.27; P = .35) and MER (HR, 1.02; 95% CI, 0.47-2.21; P = .96) cohorts.

CONCLUSIONS

These findings suggest a limited role for routine surveillance imaging in patients with FL who complete front-line therapy. Future studies should evaluate which patients may benefit from a more aggressive surveillance approach and should explore novel methods of relapse detection.

Exosomes and extracellular vesicles as liquid biopsy biomarkers in diffuse large B-cell lymphoma: Current state of the art and unmet clinical needs

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma, and it constitutes biologically heterogeneous entities. Standard first-line therapies cure ~60% of patients, the rest being either refractory or experiencing relapse. Currently, there are no robust predictive biomarkers of therapeutic response. Heterogeneity of DLBCL is partly explained by the cell of origin (COO), ie, germinal centre B cell or activated B cell, with the latter exhibiting worse prognosis. While gene expression profiling (GEP) is the gold standard for determining COO, surrogate immunohistochemical algorithms are used clinically, but show significant discordance with GEP. Recently, additional genetic subgroups with different prognoses have been reported. However, the tools/expertise required for analysis prohibit widespread deployment. Liquid biopsy-based assays show promise in providing clinically actionable information, are noninvasive and facilitate serial sampling to assess mechanisms of therapy resistance. Circulating, cell-free DNA analysis has shown enhanced sensitivity for detecting molecular alterations, but this modality cannot determine alterations of the tumor proteome or on signalling pathways. Exosomes are endosomally derived vesicles, are found in high abundance in body fluids and are readily isolated using a variety of methods. Tumour-derived exosomes can yield data regarding genetic, transcriptional, and proteomic changes useful for diagnosis, prognosis, and therapy of DLBCL. At present, standardized techniques for isolating exosomes are lacking and discriminating between exosomes from neoplastic and normal B cells is challenging. Refinements in isolation procedures are required to realize their full potential as precision medicine tools to provide comprehensive information on disease subtypes, identify prognostic factors, allow real-time monitoring of therapy response and delineate novel drug targets.

Updates on Circulating Tumor DNA Assessment in Lymphoma

PURPOSE OF REVIEW

The use of circulating tumor DNA (ctDNA) for the purposes of diagnosis, prognosis, assessment of treatment response, and monitoring for relapse is a new and developing field in lymphoma. This review aims to summarize many of the most recent advances in ctDNA applications.

RECENT FINDINGS

Recent studies have demonstrated the use of ctDNA assessment across many lymphoma subtypes including diffuse large B-cell lymphoma, follicular lymphoma, Hodgkin lymphoma, and T-cell lymphoma. In addition, many novel applications of ctDNA assessment have been described such as the development of new prognostic models, investigation of clonal evolution and heterogeneity, early assessment of treatment response, and prediction of response to targeted therapy as a form of personalized medicine. The use of ctDNA has been shown to be feasible across many lymphoma subtypes and has shown significant promise for several new applications. Additional studies will be needed to validate these findings prior to routine use in clinical practice.

Monitoring clinical outcomes in aggressive B-cell lymphoma: From imaging studies to circulating tumor DNA

Recent guidelines have de-emphasized the role of routine surveillance computed tomography (CT) scans for diffuse large B-cell lymphoma (DLBCL) patients who achieve a complete response to front-line therapy. This shift in practice recommendations was prompted by retrospective studies that failed to demonstrate clear clinical utility for surveillance CT in unselected DLBCL patients. Controversy remains, however, over the role of routine surveillance CT in the highest risk patients for treatment failure who would remain candidates for aggressive salvage therapies. Novel high-throughput sequencing methods can non-invasively monitor tumor-specific DNA in the blood and offers clear advantages designed to overcome fundamental limitations of CT scans. This review will discuss the current controversies surrounding monitoring clinical outcomes in aggressive B-cell lymphomas, with a specific emphasis on DLBCL. Fundamental limitations of imaging scans will be addressed and the potential of monitoring circulating tumor DNA as an adjunct or replacement for CT scans will be discussed.

Utility of routine surveillance imaging for diffuse large B-cell lymphoma post autologous transplant: A single center experience

Surveillance scans after autologous stem cell transplant (auto-HCT) for patients with relapsed/refractory (RR) diffuse large B Cell lymphoma (DLBCL) have no proven survival benefit. We studied survival differences among patients with RR DLBCL post auto-HCT whose recurrences were detected clinically versus with routine surveillance imaging. Among the 139 patients with RR DLBCL that underwent auto-HCT from 2000 to 2014 at our institution, 37 relapsed: 21 clinical and 16 radiological. The median time to progression was 167 days for the clinical cohort and 565 days for the radiological cohort (p = 0.03), and median overall survival (OS) was 587 days and not reached, respectively (p = 0.006). Most patients with relapsed DLBCL after auto-HCT were diagnosed clinically and were likely to be detected earlier and have a shorter OS. Relapse in patients with aggressive disease will likely be detected when clinically apparent, and the outcome of these patients is independent of the way the relapse is diagnosed. Thus, universal scanning after auto-HCT appears to have little benefit.

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

OPINION STATEMENT

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

Circulating Tumor DNA to Monitor Therapy for Aggressive B-Cell Lymphomas

OPINION STATEMENT

The goal of therapy for aggressive B-cell lymphomas such as diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL) is to achieve cure. Combination chemotherapy with rituximab cures most patients, but those with recurrent disease have a poor prognosis. Medical imaging scans such as computed tomography (CT) and positron emission tomography (PET) are the principal methods to assess response and monitor for disease relapse after therapy but are fundamentally limited by risks of radiation, cost, and a lack of tumor specificity. Novel sequencing-based DNA monitoring methods are capable of quantifying small amounts of circulating tumor DNA (ctDNA) before, during, and after therapy for mature B-cell lymphomas. Detection of ctDNA encoding clonal rearranged variable-diversity-joining (VDJ) receptor gene sequences has demonstrated improved analytical sensitivity and enhanced tumor specificity compared to imaging scans in DLBCL, offering broad clinical applicability across a range of aggressive B-cell lymphomas. Molecular monitoring of ctDNA has vaulted into the spotlight as a promising non-invasive tool with immediate clinical impact on monitoring for recurrence after therapy prior to clinical symptoms. As these clinical observations are validated, ctDNA monitoring needs to be investigated as a tool for response-adapted therapy and as a marker of minimal residual disease upon completion of therapy in aggressive B-cell lymphomas. Molecular monitoring of ctDNA holds tremendous promise that may ultimately transform our ability to monitor disease in aggressive B-cell lymphomas.

Surveillance Scans in Lymphoma: Friend or Foe?

OPINION STATEMENT

Advancements in the treatment of lymphoma over the last few decades have allowed more patients to achieve a remission after the completion of therapy. Due to the improvement in response rates, methods to detect recurrence early and accurately during follow-up, especially in patients with potential curable aggressive lymphomas, are a key. Observation has always involved close clinical follow-up with the use of physical exams and routine labs, but rapid changes in technology have allowed CT scans, PET scans, and MRIs to become an integral part of managing patients with lymphoma. While the utility of scans in initial staging and immediately after completion of therapy is well established, the use of these imaging modalities for monitoring recurrence in lymphoma patients is still controversial. Patient advocacy groups and other regulatory committees have questioned the frequency and in some cases even the need for these tests in patients without evidence of active disease given the concern for radiation-associated health risks. Additionally, the extent to which this form of testing impacts the psyche of our patients is not completely known. Given the numerous questions raised about the benefits, safety, and cost-effectiveness of CT imaging, firm guidelines are needed at this time in standard practice and within our clinical trials to limit the use of surveillance imaging. Such efforts are expected to improve the utility of these scans in asymptomatic patients, reduce healthcare costs, and reduce patient exposure to radiation.

Relapsed or Refractory Lymphoblastic Lymphoma in Children: Results and Analysis of 23 Patients in the EORTC 58951 and the LMT96 Protocols

BACKGROUND

The treatment of children with T-cell lymphoblastic lymphoma (T-LBL) and precursor B-cell lymphoblastic lymphoma (pB-LBL) has improved during the last decades. However, patients with relapsed or refractory lymphomas still have a poor prognosis.

METHODS

We report the characteristics and evolution of T-LBL and pB-LBL relapses in two multicenter prospective studies (LMT 96, European Organization for Research and Treatment of Cancer 58951).

RESULTS

From 1997 to 2008, 194 patients were included in these studies (157 T-LBL; 37 pB-LBL); among them, 23 patients underwent relapse or progression (18 T-LBL and 5 pB-LBL). The median age was 7.7 years (range 1.4-16.3). The survival rate at 8 years was 8.7% (21 deaths). The median time from diagnosis to relapse was 9 months [1-69] and 11 months [1-45] for T-LBL and pB-LBL, respectively. Twenty-two patients received a second-line treatment but remission was achieved in only seven patients. In 10 patients, intensification with hematopoietic stem cell transplantation (HSCT) was performed and four of them had a second relapse. Two patients still alive had T-LBL, experienced relapses 15 and 69 months after diagnosis, and received HSCT. Relapse during the intensive phase and second-line treatment without HSCT were identified as risk factors for bad prognosis (P = 0.01).

CONCLUSIONS

The results of second-line treatment, including intensive chemotherapy and HSCT, show that salvage treatment is still disappointing in controlling refractory forms. Early identification of patients at high risk of relapse is mandatory, allowing earlier intensification. Valid prognostic parameters, such as biological markers, are needed. International cooperation is warranted to collect more data on these rare diagnoses.

Role of computed tomography on large B-cell non-Hodgkin's lymphoma follow-up and the risk of radiation-induced neoplasm: A retrospective cohort study

INTRODUCTION

To evaluate the role of surveillance computed tomography (CT) in detection of tumor relapse after complete remission for large-cell lymphoma and to estimate the cancer risk related to those examinations.

MATERIALS AND METHODS

We retrospectively identified the cases of large-cell lymphoma diagnosed at our institution during a fifteen years period. We extracted from charts the information needed. Agreement between clinical and radiological evaluation for relapse detection was determined with index kappa and McNemar tests. We analysed the surveillance CT examinations performed to the patients in complete remission with no recurrence during the follow-up period and we estimated the life attributable risk (LAR) of radiation-induced cancer above base line using the approach of the Biological Effects of Ionizing Radiation (BEIR) VII.

RESULTS

184 patients with biopsy confirmed large-cell lymphoma were included. Complete remission was attained in 125 patients. After a median follow-up of 93.73 months, 97 of them remain in remission. Relapse was confirmed in 28 patients; only 3 of them were asymptomatic. Kappa and McNemar analyses revealed good agreement for diagnosis of recurrence and significant difference for exclusion of relapse. Patients in remission received a median of 6 surveillance CT examinations. Fifty-seven patients had total cumulative doses greater than 100mSv. The mean increase in estimated radiation-induced cancer risk was 0.5%.

CONCLUSION

Our results suggest that periodic CT examinations have a limited role in detecting relapse in large-cell lymphoma as the clinical surveillance dictates the patient management.

Routine Imaging for Diffuse Large B-Cell Lymphoma in First Complete Remission Does Not Improve Post-Treatment Survival: A Danish–Swedish Population-Based Study

Purpose

Routine imaging for diffuse large B-cell lymphoma (DLBCL) in first complete remission (CR) is controversial and plays a limited role in detecting relapse. This population-based study compared the survival of Danish and Swedish patients with DLBCL for whom traditions for routine imaging have been different.

Patients and Methods

Patients from the Danish and Swedish lymphoma registries were included according to the following criteria: newly diagnosed DLBCL from 2007 to 2012, age 18 to 65 years, and CR after R-CHOP/CHOEP. Follow-up for Swedish patients included symptom assessment, clinical examinations, and blood tests at 3- to 4-month intervals for 2 years, with longer intervals later in follow-up. Imaging was only recommended when relapse was clinically suspected. Follow-up for Danish patients was similar but included routine imaging (usually computed tomography every 6 months for 2 years).

Results

Danish (n = 525) and Swedish (n = 696) patients with DLBCL had comparable baseline characteristics. Cumulative 2-year progression rate after CR was 6% (95% CI, 4 to 9) for International Prognostic Index (IPI) ≤ 2 versus 21% (95% CI, 13 to 28) for IPI > 2. Age > 60 years (hazard ratio [HR], 2.3; 95% CI, 1.6 to 3.4), elevated lactate dehydrogenase (HR, 2.3; 95% CI, 1.4 to 3.8), B symptoms (HR, 1.7; 95% CI, 1.1 to 2.5), and Eastern Cooperative Oncology Group performance status ≥ 2 (HR, 1.8; 95% CI, 1.0 to 3.0) were associated with worse post-CR survival. Imaging-based follow-up strategy had no impact on survival, neither for all patients nor for IPI-specific subgroups.

Conclusion

DLBCL relapse after first CR is infrequent, and the widespread use of routine imaging in Denmark did not translate into better survival. This favors follow-up without routine imaging and, more generally, a shift of focus from relapse detection to improved survivorship.

Imaging of non-Hodgkin lymphomas: diagnosis and response-adapted strategies

Optimal lymphoma management requires accurate pretreatment staging and reliable assessment of response, both during and after therapy. Positron emission tomography with computerized tomography (PET/CT) combines functional and anatomical imaging and provides the most sensitive and accurate methods for lymphoma imaging. New guidelines for lymphoma imaging and recently revised criteria for lymphoma staging and response assessment recommend PET/CT staging, treatment monitoring, and response evaluation in all FDG-avid lymphomas, while CT remains the method of choice for non-FDG-avid histologies. Since interim PET imaging has high prognostic value in lymphoma, a number of trials investigate PET-based, response-adapted therapy for non-Hodgkin lymphomas (NHL). PET response is the main determinant of response according to the new response criteria, but PET/CT has little or no role in routine surveillance imaging, the value which is itself questionable. This review presents from a clinical point of view the evidence for the use of imaging and primarily PET/CT in NHL before, during, and after therapy. The reader is given an overview of the current PET-based interventional NHL trials and an insight into possible future developments in the field, including new PET tracers.

Use of subsequent PET/CT in diffuse large B-cell lymphoma patients in complete remission following primary therapy

Interim 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (I-PET/CT) is a powerful tool for monitoring the response to therapy in diffuse large B-cell lymphoma (DLBCL). This retrospective study aimed to determine when and how to use I-PET/CT in DLBCL. A total of 197 patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) were enrolled between October 2005 and July 2011; PET/CT was performed at the time of diagnosis (PET/CT0), after 2 and 4 cycles of chemotherapy (PET/CT2 and PET/CT4, respectively), and at the end of treatment (F-PET/CT). According to the International Harmonization Project for Response Criteria in Lymphoma, 110 patients had negative PET/CT2 scans, and 87 had positive PET/CT2 scans. The PET/CT2-negative patients had significantly higher 3-year progression-free survival rate (75.8% vs. 38.2%) and 3-year overall survival rate (93.5% vs. 55.6%) than PET/CT2-positive patients. All PET/CT2-negative patients remained negative at PET/CT4, but 3 were positive at F-PET/CT. Among the 87 PET/CT2-positive patients, 57 remained positive at F-PET/CT, and 32 progressed during chemotherapy (15 at PET/CT4 and 17 at F-PET/CT). Comparing PET/CT4 with PET/CT0, 7 patients exhibited progression, and 8 achieved partial remission. Comparing F-PET/CT with PET/CT0, 10 patients exhibited progression, and 7 achieved partial remission. In conclusion, our results indicate that I-PET/CT should be performed after 2 rather than 4 cycles of immunochemotherapy in DLBCL patients. There is a limited role for subsequent PET/CT in the detection of relapse in PET/CT2-negative patients, but repeat PET/CT is required if the PET/CT2 findings are positive.

Utility of routine post-therapy surveillance imaging in diffuse large B-cell lymphoma

PURPOSE

We examined the utility of post-therapy surveillance imaging in a large, prospectively enrolled cohort of patients with diffuse large B-cell lymphoma (DLBCL) from the United States and confirmed our results in an independent cohort of patients from France.

METHODS

Patients with newly diagnosed DLBCL and treated with anthracycline-based immunochemotherapy were identified from the Molecular Epidemiology Resource (MER) of the University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellence and the Léon Bérard Cancer Center, Lyon, France. In those with relapse, details at relapse and outcomes were abstracted from records.

RESULTS

680 individuals with DLBCL were identified from the MER, 552 (81%) of whom achieved remission after induction. 112 of the 552 patients (20%) suffered a relapse. The majority (64%) of relapses were identified before a scheduled follow-up visit. Surveillance imaging detected DLBCL relapse before clinical manifestations in nine out of 552 patients (1.6%) observed after therapy. In the Lyon cohort, imaging identified asymptomatic DLBCL relapse in four out of 222 patients (1.8%). There was no difference in survival after DLBCL relapse in patients detected at scheduled follow-up versus before scheduled follow-up in both the MER (P = .56) and Lyon cohorts (P = .25).

CONCLUSION

The majority of DLBCL relapses are detected outside of planned follow-up, with no difference in outcome in patients with DLBCL detected at a scheduled visit compared with patients with relapse detected outside of planned follow-up. These data do not support the use of routine surveillance imaging for follow-up of DLBCL.

Diagnosis of mantle-cell lymphoma relapse by 18F-FDG PET/CT after water gastric distention

Proper gastric distention with oral contrast agents is a well-recognized CT technique for imaging of the stomach. We present the basal and after water ingestion F-FDG PET/CT images that show abnormal focal FDG uptake in a clinically unsuspected gastric relapse of mantle-cell lymphoma. The patient had achieved complete remission after chemoradiotherapy and autologous stem-cell transplantation 3 years before. The images obtained after the distention of the stomach with water were crucial to confirm the presence of an FDG-avid lesion in the antrum and to distinguish between physiological and pathological radiotracer uptake. Histological analysis confirmed mantle-cell lymphoma infiltration.

Role of routine imaging in detecting recurrent lymphoma: A review of 258 patients with relapsed aggressive non-Hodgkin and Hodgkin lymphoma

After first-line therapy, patients with Hodgkin lymphoma (HL) and aggressive non-HL are followed up closely for early signs of relapse. The current follow-up practice with frequent use of surveillance imaging is highly controversial and warrants a critical evaluation. Therefore, a retrospective multicenter study of relapsed HL and aggressive non-HL (nodal T-cell and diffuse large B-cell lymphomas) was conducted. All included patients had been diagnosed during the period 2002-2011 and relapsed after achieving complete remission on first-line therapy. Characteristics and outcome of imaging-detected relapses were compared with other relapses. A total of 258 patients with recurrent lymphoma were included in the study. Relapse investigations were initiated outside preplanned visits in 52% of the patients. Relapse detection could be attributed to patient-reported symptoms alone or in combination with abnormal blood tests or physical examination in 64% of the patients. Routine imaging prompted relapse investigations in 27% of the patients. The estimated number of routine scans per relapse was 91-255 depending on the lymphoma subtype. Patients with imaging-detected relapse had lower disease burden (P = 0.045) and reduced risk of death following relapse (hazard ratio = 0.62, P = 0.02 in multivariate analysis). Patient-reported symptoms are still the most common factor for detecting lymphoma relapse and the high number of scans per relapse calls for improved criteria for use of surveillance imaging. However, imaging-detected relapse was associated with lower disease burden and a possible survival advantage. The future role of routine surveillance imaging should be defined in a randomized trial.

Symptom-oriented clinical detection versus routine imaging as a monitoring policy of relapse in patients with diffuse large B-cell lymphoma

This study aimed at evaluating the role of routine imaging versus symptom-directed unplanned early outpatient department (OPD) visits in patients with diffuse large B-cell lymphoma (DLBCL) in complete remission (CR) by analyzing the patterns and outcomes of OPD visits for disease monitoring. Patients with DLBCL in CR after treatment in the rituximab era with any OPD monitoring visit were analyzed. A total of 856 OPD visits were recorded: 501 visits were with routine imaging, 322 were without routine imaging and 33 visits (3.9%) were unplanned early visits due to abnormal symptoms. Of the 106 analyzed patients, 15 experienced a relapse (median follow-up duration of 38.1 months). Routine imaging showed an unsatisfactory positive predictive value due to frequent false-positive visits, and a substantial number of patients with false-positive imaging underwent unnecessary biopsies or additional scans. Compared with planned OPD visits, unplanned early visits were highly related to relapse.

Surveillance imaging for lymphoma: pros and cons

There is no international consensus on the optimal frequency or duration of computed tomography or positron emission tomography scanning for surveillance in patients who achieve complete remission after initial therapy for lymphoma. Although some clinical practice guidelines suggest periodic imaging is reasonable, others suggest little or no benefit to this practice. From a theoretical perspective, the frequency and duration of surveillance imaging is largely dependent upon the lymphoma subtype. Aggressive lymphomas with a fast growth rate will require surveillance more frequently and for a shorter duration compared to the indolent lymphomas. Historically, relapse has been detected in a majority of patients based upon clinically evident signs and symptoms. Currently, no study has demonstrated an overall survival difference for patients with relapse detected by imaging as opposed to clinical evaluation, although one study did demonstrate a lower second-line International Prognostic Index in patients with relapse detected by surveillance imaging. Enthusiasm for this finding has been tempered by recent studies highlighting the potential long-term risk of secondary malignancies because of ionizing radiation exposure from diagnostic imaging. These factors along with the significant costs associated with diagnostic imaging have contributed to an ongoing debate regarding the relative costs, risks, and benefits of radiographic surveillance. Herein we present perspectives for and against routine surveillance imaging in an effort to facilitate a better understanding of the issues relevant to what is ultimately a clinical decision made by an oncologist and his or her patient.

Fluoro-deoxy-glucose positron emission tomography/computed tomography in lymphoma: A pictorial essay

F-18 fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT) has emerged as a powerful imaging modality in the field of oncology. F-18 FDG PET/CT is now an established tool in the management of lymphoma. This has been shown to be useful in staging, detection of bone marrow involvement (BMI), early response assessment and end of therapy response assessment in lymphoma. Interpretation of F-18 FDG PET/CT in lymphoma is carried out by various qualitative response assessment criteria. London criteria are used for interpretation of interim PET/CT and International Harmonization Project (IHP) criteria are used to interpret PET/CT done after the end of chemotherapy. Quantitative analysis is also found to be useful in assessment of response early after two cycles of chemotherapy in patients with diffuse large B cell lymphoma (DLBCL). This pictorial essay provides few images describing the FDG avidity of lymphoma, patterns of bone marrow uptake and their relevance in predicting BMI, role of staging PET/CT, quantitative analysis in response assessment, example images of response according to London criteria and IHP criteria. Few pitfalls in imaging of lymphoma with PET/CT are also discussed in the images legend.

When should FDG-PET be used in the modern management of lymphoma?

Positron Emission Tomography (PET) is a functional imaging technique that, combined with computerized tomography (PET-CT), is increasingly used in lymphoma. Most subtypes accumulate fluorodeoxyglucose (FDG) and the increased sensitivity of PET-CT, especially for extranodal disease, compared to CT, makes PET-CT an attractive staging tool. The availability of a staging PET-CT scan also improves the accuracy of subsequent response assessment. 'Interim' PET-CT can be used to assess early response and end-of-treatment PET-CT assesses remission. Clinical trials are currently seeking to establish whether the predictive value of PET-CT can be successfully used to guide individual treatment to reduce toxicity and/or to improve outcomes. Standardized methods for performing and reporting PET have been developed in the context of trials. The role of PET in transplantation selection is currently evolving, as it appears to be more accurate and prognostic than CT. The role of FDG PET-CT throughout the management course in patients with lymphoma is explored in this review, with areas discussed that may limit the use of PET-CT imaging which clinicians should be familiar with to inform practice.

The lack of evidence for PET or PET/CT surveillance of patients with treated lymphoma, colorectal cancer, and head and neck cancer: a systematic review

PET and PET/CT are widely used for surveillance of patients after cancer treatments. We conducted a systematic review to assess the diagnostic accuracy and clinical impact of PET and PET/CT used for surveillance in several cancers.

METHODS

We searched MEDLINE and Cochrane Library databases from 1996 to March 2012 for English-language studies of PET or PET/CT used for surveillance of patients with lymphoma, colorectal cancer, or head and neck cancer. We included prospective or retrospective studies that reported test accuracy and comparative studies that assessed clinical impact.

RESULTS

Twelve studies met our inclusion criteria: 6 lymphoma (n = 767 patients), 2 colorectal cancer (n = 96), and 4 head and neck cancer (n = 194). All studies lacked a uniform definition of surveillance and scan protocols. Half the studies were retrospective, and a third were rated as low quality. The majority reported sensitivities and specificities in the range of 90%-100%, although several studies reported lower results. The only randomized controlled trial, a colorectal cancer study with 65 patients in the surveillance arm, reported earlier detection of recurrences with PET and suggested improved clinical outcomes.

CONCLUSION

There is insufficient evidence to draw conclusions on the clinical impact of PET or PET/CT surveillance for these cancers. The lack of standard definitions for surveillance, heterogeneous scanning protocols, and inconsistencies in reporting test accuracy preclude making an informed judgment on the value of PET for this potential indication.

Limited role for surveillance PET-CT scanning in patients with diffuse large B-cell lymphoma in complete metabolic remission following primary therapy

Background:

The usefulness of positron emission tomography with computed tomography (PET–CT) in the surveillance of patients with diffuse large B-cell lymphoma (DLBCL) in complete metabolic remission after primary therapy is not well studied.

Methods:

We performed a retrospective review of our database between 2002 and 2009 for patients with de novo DLBCL who underwent surveillance PET–CT after achieving complete metabolic response (CMR) following primary therapy.

Results:

Four-hundred and fifty scans were performed in 116 patients, with a median follow-up of 53 (range 8–133) months from completion of therapy. Thirteen patients (11%) relapsed: seven were suspected clinically and six were subclinical (all within first 18 months). The positive predictive value in patients with international prognostic index (IPI) <3 was 56% compared with 80% in patients with IPI⩾3. Including indeterminate scans, PET–CT retained high sensitivity 95% and specificity 97% for relapse.

Conclusion:

Positron emission tomography with computed tomography is not useful in patients for the majority of patients with diffuse large B-cell lymphoma in CMR after primary therapy, with the possible exception of patients with baseline IPI ⩾3 in the 18 months following completion of primary therapy. This issue could be addressed by a prospective clinical trial.

Strikingly high false positivity of surveillance FDG-PET/CT scanning among patients with diffuse large cell lymphoma in the rituximab era

Predictive value (PV) of surveillance fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with diffuse large B-cell lymphoma (DLBCL) treated with chemotherapy-rituximab (R) versus chemotherapy only, remains unclear. The aim of the current study was to compare the performance of surveillance PET in DLBCL patients receiving CHOP (cyclophosphamide, hydroxydaunorubicin hydrochloride, vincristine, and prednisone) alone versus CHOP-R. Institutional database was retrospectively searched for adults with newly diagnosed DLBCL, receiving CHOP or CHOP-R, who achieved complete remission and underwent surveillance PETs. Follow-up (FU) PET was considered positive for recurrence in case of an uptake unrelated to physiological or known benign process. Results were confirmed by biopsy, imaging and clinical FU. One hundred nineteen patients, 35 receiving CHOP and 84 CHOP-R, who underwent 422 FU-PETs, were analyzed. At a median PET-FU of 3.4 years, 31 patients relapsed (17 vs. 14, respectively; P = 0.02). PET detected all relapses, with no false-negative studies. Specificity and positive PV (PPV) were significantly lower for patients receiving CHOP-R vs. CHOP (84% vs. 87%, P = 0.023; 23% vs. 74%, P < 0.0001), reflecting a higher false-positive (FP) rate in subjects receiving CHOP-R (77% vs. 26%, P < 0.001). In the latter group, FP-rate remained persistently high up to 3 years post-therapy. Multivariate analysis confirmed rituximab to be the most significant predictor for FP-PET. In conclusion, routine surveillance FDG-PET is not recommended in DLBCL treated with rituximab; strict criteria identifying patients in whom FU-PET is beneficial are required.

Positron emission tomographic scans in lymphoma: convention and controversy

The use of sensitive and specific imaging techniques for accurate initial staging and evaluation of response to therapy in patients with lymphoma is essential for their optimal management. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) integrated with computed tomography (CT) has emerged as a powerful imaging tool and is being routinely used in staging, response evaluation, and posttreatment surveillance in patients with non-Hodgkin lymphoma and Hodgkin lymphoma. PET/CT is currently widely used in clinical practice, but the established clinical benefit is currently restricted to the posttreatment evaluation of Hodgkin lymphoma, diffuse large B-cell lymphoma, and follicular lymphoma. Although used in other histologic subtypes and in other clinical situations including response assessment, its impact on patient outcome remains to be demonstrated. We performed a literature search of PubMed from 1999 to 2011 using the following keywords: PET scan, FDG-PET, PET/CT, lymphoma. This review addresses the challenges and controversies in the use of PET/CT scans in the management of patients with lymphoma.

Utility of positron emission tomography scans in mantle cell lymphoma

Positron emission tomography (PET) scans are widely used in patients with lymphoma but little is known about their utility in mantle cell lymphoma (MCL). MCL patients were included from two prospective trials and one observational study at our institution. A total of 276 PET scans were performed among 52 patients. After a median follow-up of 37.5 months, the 3-year event-free survival (EFS) and overall survival (OS) were 73% (95% confidence interval [CI]: 61-85%) and 92% (95% CI 85-100%), respectively. There were 34 pretreatment PET scans, 26 interim, 28 end-of-treatment, 162 surveillance, and 26 scans at relapse or beyond. Pretreatment PETs were positive in 94%. A negative interim or end-of-therapy PET scan was not significantly associated with better EFS or OS, but no deaths were observed in patients who had a negative interim or end-of-therapy PET. Surveillance PET scans had a high false positive rate (35%) and low positive predictive value (8%). PET scans contributed to an earlier diagnosis of relapse in only two out of the 18 patients (11%) who relapsed. PET scans did not meaningfully contribute to staging or surveillance of MCL patients in this study. There was a trend toward improved survival in patients who had a negative end-of-therapy PET scan.