[Role of FDG-PET/CT in diffuse large B-cell lymphoma]

FDG-PET/CT has been widely used not only at the time of diagnosis of non-Hodgkin's lymphoma but also during and after treatment. With the help of large amount of data on Hodgkin's lymphoma, for which FDG-PET is extraordinarily useful, evidence is also rapidly accumulating for non-Hodgkin's lymphoma. Currently, there is a consensus that FDG-PET/CT is effective in stratifying the prognosis of non-Hodgkin's lymphoma in a PET-avid disease, especially diffuse large B-cell lymphoma (DLBCL). However, in the enormous evidence accumulated till date, the variability in the clinical conditions of the patients, timing, and the FDG-PET/CT assessment method makes it difficult to overlook and understand the complete picture. In this article, we will review the position of FDG-PET/CT in the response assessment of DLBCL, evolution of evaluation methods, and evidence for determining therapeutic efficacy using FDG-PET/CT and for modifying treatment based on the FDG-PET/CT results.

Semiquantitative analysis of interim 18F-FDG PET is superior in predicting outcome in Hodgkin lymphoma patients compared to visual analysis

PURPOSE

To investigate the prognostic value of interim PET (PETi) in adult HL patients, comparing visual with semiquantitative analysis.

MATERIAL AND METHODS

Retrospective analysis of Hodgkin's lymphoma (HL) patients diagnosed between 2012 and 2016 in the Onco-hematology Department of Instituto Português de Oncologia - Porto (median follow-up: 46.5 months [2.6-66.4]). Fifty-eight patients with available PET at diagnosis (PET0) and PETi data were included. PETi scans were analyzed according to Deauville 5-point scale (5-PS), and cut-off values for changes in maximum standardized uptake value [SUVmax], peak SUV [SUVpeak], metabolic tumour volume [MTV] and total lesion glycolysis index [TLG] between PETi and PET0 were computed using ROC analysis. Visual and semiquantitative data were compared with each other in the prediction of patient outcomes.

RESULTS

Semiquantitative analysis obtained a higher sensitivity for persistent/relapsed disease compared to the 5-PS (70% vs. 10%, respectively), but lower specificity. It also demonstrated better predictive performance for response to first-line therapy (negative predictive value >92%). The positive predictive value was similar for all five measurements. At 60 months of follow-up, there was a significant difference between the progression free survival (PFS) curves of patients with positive and negative PETi according to ΔSUVmax (56.9% vs. 88.0%, p<0.05), ΔSUVpeak (55.9% vs. 88.1%, p<0.05), ΔMTV (35.3% vs. 88.7%, p<0.05), and ΔTLG (42.4% vs. 88.1%, p<0.05). Statistical significance was not reached when considering 5-PS results.

DISCUSSION

PETi interpretation according to a semiquantitative approach appears to discriminate HL patients better than the visual 5-PS analysis. This could allow better detection of persistent or early relapsed disease, while a negative PETi result could support de-escalating therapy intensity.

Semiquantitative analysis of interim 18F-FDG PET is superior in predicting outcome in Hodgkin lymphoma patients compared to visual analysis

PURPOSE

To investigate the prognostic value of interim PET (PETi) in adult HL patients, comparing visual with semiquantitative analysis.

MATERIAL AND METHODS

Retrospective analysis of Hodgkin's Lymphoma (HL) patients diagnosed between 2012 and 2016 in the Onco-Hematology Department of Instituto Português de Oncologia - Porto (median follow-up: 46.5 months [2,6-66,4]). Fifty-eight patients with available PET at diagnosis (PET0) and PETi data were included. PETi scans were analysed according to Deauville 5-point scale (5-PS), and cut-off values for changes in maximum standardized uptake value [SUVmax], peak SUV [SUVpeak], metabolic tumour volume [MTV] and total lesion glycolysis index [TLG] between PETi and PET0 were computed using ROC analysis. Visual and semiquantitative data were compared with each other in the prediction of patient outcomes.

RESULTS

Semiquantitative analysis obtained a higher sensitivity for persistent/relapsed disease compared to the 5-PS (70% vs. 10%, respectively), but lower specificity. It also demonstrated better predictive performance for response to first-line therapy (negative predictive value > 92%). The positive predictive value was similar for all five measurements. At 60 months of follow-up, there was a significant difference between the progression free survival (PFS) curves of patients with positive and negative PETi according to ΔSUVmax (56.9% vs. 88.0%, p < 0.05), ΔSUVpeak (55.9% vs 88.1%, p< 0.05), ΔMTV (35.3% vs. 88.7%, p< 0.05), and ΔTLG (42.4% vs. 88.1%, p< 0.05). Statistical significance wasn't reached when considering 5-PS results.

DISCUSSION

PETi interpretation according to a semiquantitative approach appears to discriminate HL patients better than the visual 5-PS analysis. This could allow better detection of persistent or early relapsed disease, while a negative PETi result could support de-escalating therapy intensity.

Role of FDG PET-CT in the treatment management of Hodgkin lymphoma

Fluorodeoxyglucose (FDG) positons emission tomography (PET)-computed tomography (CT) is used in many ways at baseline and during the treatment of patients with Hodgkin lymphoma. Many properties of the technique are used in the different steps of patient's management. Initial staging with PET-CT is more accurate than conventional imaging and PET-CT also became the gold standard imaging at the end of treatment with a negative PET-CT mandatory for reaching a complete remission. Early assessment of response by PET-CT is one of the most powerful prognostic factors for progression-free survival of patients with localized and advanced stages and allows guiding treatment. Conversely, previous studies showed that there is no role of FDG PET-CT for the patient's follow-up.

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

BACKGROUND

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Treatment of advanced-stage Hodgkin lymphoma

There is now good evidence that the escalated BEACOPP regimen (bleomycin, etoposide, adriamycin, cyclophosphamide, vincristine, procarbazine, prednisone) is more effective in controlling advanced-stage Hodgkin lymphoma (HL) than the widely used ABVD regimen (adriamycin, bleomycin, vinblastine, dacarbazine), but the extra efficacy comes at the expense of both short- and long-term toxicity, and there is debate as to whether overall survival is affected. Baseline prognostic factors have proven of limited utility for determining which patients require more intensive therapy and recent studies have sought to use interim fluoro-deoxyglucose positron emission tomography (FDG-PET) evaluation as a means to guide the modulation of treatment, both upwards and downwards in intensity. These suggest that if treatment starts with ABVD then patients remaining PET-positive after 2 months can be salvaged with escalated BEACOPP in around 65% of cases, but those becoming PET-negative may still experience recurrences in 15%-20%, an event that is more common in those with more advanced disease at presentation. There are early data to suggest that starting with escalated BEACOPP may reduce the rate of recurrence after a negative interim PET to less than 10%. This may be an attractive approach for those with very high-risk features at presentation, but risks overtreating many patients if applied nonselectively. New regimens incorporating antibody-drug conjugates may shift the balance of efficacy and toxicity once again, and further studies are underway to evaluate this.

Treatment of early-stage Hodgkin lymphoma

Hodgkin lymphoma (HL) has become one of the best curable malignancies today. This is particularly true for patients with early-stage disease. Today, most patients in this risk group are treated with a combination of chemotherapy followed by small-field radiotherapy. More recent clinical trials such as the German Hodgkin Study Group (GHSG) HD10 study demonstrated, that even two cycles of ABVD followed by 20 Gy involved-field radiation therapy (IF-RT) are sufficient and result in more than 90% of patients being cured. The current treatment for early unfavorable patients is either four cycles of ABVD plus 30 Gy IF-RT or two cycles of BEACOPPbaseline followed by two cycles of ABVD plus IF-RT. Here, the European Organization for Research and Treatment of Cancer (EORTC) demonstrated that in positron emission tomography (PET)-positive patients after two cycles of ABVD, treatment switched to two cycles of BEACOPPbaseline plus radiotherapy results in significantly improved outcomes. Other aspects including attempts to further reduce intensity of treatment will be discussed.

Baseline and ongoing PET-derived factors predict detrimental effect or potential utility of 18F-FDG PET/CT (FDG-PET/CT) performed for surveillance in asymptomatic lymphoma patients in first remission

PURPOSE

To identify both clinical and FDG PET/CT-derived factors predicting the occurrence of relapse, or conversely, the likelihood of false positive findings in surveillance FDG-PET/CT studies (PETsv).

METHODS

The study included 149 asymptomatic patients with Hodgkin's lymphoma (HL) (n = 55) or diffuse large B cell lymphoma (DLBCL) (n = 94) in first remission. PETSv studies were performed 12, 18, 24 and 36 months thereafter. Logistic regression analysis was performed to identify clinical and imaging-derived predictors of either PET-detected relapse or false-positive (FP) results. Tested clinical variables were: 1) age, 2) HL vs. DLBCL, 3) stage of disease, 4) bulky disease, 5) previous radiotherapy. PET/CT-derived variables were: 1) maximum standardized uptake value at baseline, 2) size-incorporated maximum standardized uptake value (SIMaxSUV) at baseline, 3) positive interim PET(PET-2), 4) presence of hot spots likely to be unrelated to the disease in final PET, 5) residual non-FDG avid mass.

RESULTS

Accuracy was 88 % for PETsv1, 95 % for PETsv2, 95 % for PETsv3 and 91 % for PETsv4. However, PPV was relatively low in all PETsv. Best predictors of relapse were result of interim PET, HL versus NHL type, SIMaxSUV, age ≥ 60. Best predictors of FP were previous radiotherapy and hot spots unrelated to the disease in final PET.

CONCLUSIONS

The present study confirms the need of restricting the use of surveillance PET/CT to patients at high risk of relapse. Information derived from PET/CT performed at baseline (metabolic disease burden), in the course (PET2) and at the end of therapy (unrelated hot spots) can help to select high-risk patients and also to identify patients more likely to present equivocal findings at PETsv.