Role of interim and end of treatment positron emission tomography for response assessment and prediction of relapse in posttransplant lymphoproliferative disorder.

Background: Fluorine-18-fluorodeoxyglucose positron emission tomography (PET) has an established and central role in diagnosis, staging and response evaluation of lymphoproliferative diseases. It has shown a high sensitivity and specificity at diagnosis in posttransplant lymphoproliferative disorders (PTLDs). However, little is known about the performance of interim and end of treatment (EOT) PET in PTLD patients with regards to response assessment, relapse prediction and outcome. Methods: We performed a single-center retrospective study in which we analyzed consecutive patients diagnosed with CD20-positive PTLD after solid organ transplantation between 2008 and 2017, who all received risk-stratified sequential treatment according to the PTLD-1 phase II trial. Interim and EOT PET studies were scored according to the Deauville criteria. Results: Forty-one patients were included with median follow-up of 41.5 months (range 1-108). Positive and negative predictive values for disease recurrence were 13% and 85% for interim and 33% and 87% for EOT PET, respectively. There was no significant difference in overall survival, progression-free survival nor time to progression between negative versus positive patients on interim and EOT scans. Conclusions: Negative interim and/or negative end of treatment PET identify PTLD patients with low risk of disease recurrence.

External quality assessment for KRAS testing is needed: setup of a European program and report of the first joined regional quality assessment rounds.

The use of epidermal growth factor receptor-targeting antibodies in metastatic colorectal cancer has been restricted to patients with wild-type KRAS tumors by the European Medicines Agency since 2008, based on data showing a lack of efficacy and potential harm in patients with mutant KRAS tumors. In an effort to ensure optimal, uniform, and reliable community-based KRAS testing throughout Europe, a KRAS external quality assessment (EQA) scheme was set up. The first large assessment round included 59 laboratories from eight different European countries. For each country, one regional scheme organizer prepared and distributed the samples for the participants of their own country. The samples included unstained sections of 10 invasive colorectal carcinomas with known KRAS mutation status. The samples were centrally validated by one of two reference laboratories. The laboratories were allowed to use their own preferred method for histological evaluation, DNA isolation, and mutation analysis. In this study, we analyze the setup of the KRAS scheme. We analyzed the advantages and disadvantages of the regional scheme organization by analyzing the outcome of genotyping results, analysis of tumor percentage, and written reports. We conclude that only 70% of laboratories correctly identified the KRAS mutational status in all samples. Both the false-positive and false-negative results observed negatively affect patient care. Reports of the KRAS test results often lacked essential information. We aim to further expand this program to more laboratories to provide a robust estimate of the quality of KRAS testing in Europe, and provide the basis for remedial measures and harmonization.

Aggressive and indolent non-Hodgkin's lymphoma: response assessment by integrated international workshop criteria.

Until recently, response assessment in patients with lymphoma was primarily performed by computed tomography (CT). Based on CT, International Workshop Criteria (IWC) were developed and widely used. Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) is a more sensitive and specific imaging technique for the detection of residual disease in lymphoma, and Revised Integrated International Workshop Criteria (IWC + PET) were recently proposed by the members of the International Harmonization Project (IHP), which combine both imaging techniques. We determined whether these new IWC + PET-criteria, can more accurately predict outcome compared to IWC-criteria in aggressive and indolent non-Hodgkin's lymphoma (NHL), and therefore correlated IWC and IWC + PET response with time-to-next-treatment (TNT) in 69 patients with NHL. We demonstrated that IWC + PET-guidelines are highly recommended over IWC-guidelines for patients with potentially-curable and routinely FDG-avid lymphoma. In contrast, no additional value of IWC + PET was demonstrated in a small group of patients with incurable histological subtypes.

Hodgkin lymphoma: Response assessment by revised International Workshop Criteria.

Until recently, response assessment in patients with Hodgkin's lymphoma (HL) was primarily performed by computed tomography (CT). Based on CT, International Workshop Criteria (IWC) were developed and widely used. Fluorodeoxyglucose positron emission tomography (FDG-PET) has a higher sensitivity and specificity compared with that of CT, and Revised International Workshop Criteria (IWC + PET) were recently proposed, which combine both imaging techniques. We determined whether these integrated IWC + PET-criteria can more accurately predict outcome compared with IWC-criteria in 56 patients with HL. Of the original 56 patients, nine patients relapsed and 47 are still in remission after a median follow-up of 9 years. Based on IWC-criteria, 15 patients had a complete remission (CR) after chemotherapy, 20 had complete remission unconfirmed (CRu), 19 had partial remission (PR) and two had stable disease (SD). In comparison, by IWC + PET, 47 had CR, seven had PR and two had SD. For IWC, outcome was not significantly different in patients with CR/CRu compared to PR (P = 0.61), while for IWC + PET criteria, time-to-next-treatment was significantly shorter in patients with PR compared to CR (P = 0.01). Therefore, IWC + PET-guidelines provide a more accurate response classification compared with that of IWC-guidelines, and are the preferred method for response assessment in patients with Hodgkin's lymphoma.