Utility of Positron Emission Tomography (PET) Scanning in Managing Patients with Hodgkin Lymphoma

Abstract

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 CTbased 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 falsepositive 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.

Tandem high-dose chemotherapy strategy as first-line treatment of primary disseminated multifocal Ewing sarcomas in children, adolescents and young adults

“…22,23 The use of PET-CT response (PERCIST 15 ) to guide ES treatment has so far not been evaluated, whereas it is routinely used for this purpose in Hodgkin disease. 24 Early metastatic relapses after Mel/Bu at sites that were not involved at diagnosis, especially in the patient who received local treatment for metastasis, suggests persistent micrometastatic disease, such as that observed in other tumour types. 25 This finding does not argue in favour of local treatment of metastases, although it has been suggested by others for ES and other sarcoma types (for example, rhabdomyosarcoma).…”

Fluorine-18 fluorodeoxyglucose PET-CT for extranodal staging of non-Hodgkin and Hodgkin lymphoma

“…Various groups have used care-dose CT without the injection of intravenous iodinated contrast agent for attenuation, correction, or anatomical correlation. Previous studies revealed that 18 F-FDG PET-CT has a higher sensitivity and specificity than CE-CT in the evaluation of HL and high-grade NHL (3,4,(7)(8)(9)(10)(11). Moreover, several studies have suggested that PET imaging with care-dose unenhanced CT alone might be sufficient for staging, therapy monitoring, or follow-up in patients with HL and aggressive NHL, except in special cases (7,12).…”

“…This provides a significant advantage for the evaluation of lymphoproliferative malignancies, particularly for the detection of lymphomatous involvement in organs and nodes of normal size without any mass. Several studies suggest that the sensitivity and specificity of 18 F-FDG PET-CT for the assessment of nodal and extranodal involvement were higher than those of standard contrast-enhanced CT (CE-CT) (3,4,(7)(8)(9)(10)(11). These benefits make 18 F-FDG PET-CT the standard imaging technique for the initial staging, therapy response evaluation and restaging of patients with lymphoma.…”

Prognostic Factors in Follicular Lymphoma in the Rituximab Era: How to Identify a High-Risk Patient?

“…Imaging of viable tumour tissue is a brand new modality in oncology. Induction of post-treatment PET negativity is associated with a significantly better prognosis in patients with diffuse large cell lymphoma and Hodgkin's lymphoma 41,42 . A new generation of hybrid PET/CT scanners provides an unprecedented quality of imaging by fusing a morphological CT scan and functional (metabolic) image from a PET detector 43 .…”