Hodgkin lymphoma : effect of positron emission tomography results after two cycles of chemotherapy on the final outcome of the treatment

Do nedavno, evaluacija pacijenata s Hodgkinovim limfomom nakon kemoterapije i radioterapije se temeljila na procjeni morfoloških parametara, kao što su dimenzije tumorskih masa i uvećani limfnih čvorovi, pomoću slikovnih metoda, od kojih je najvažnija bila CT čitavog tijela. Međutim, u procjeni odgovora na terapiju, CT ne daje podatke o vijabilnosti tih lezija. Kao rezultat takvih ograničenja, razvijene su nove metode koje su postupno uvedene u kliničku praksu, kao što je FDG-PET. Ta molekularna dijagnostička pretraga se temelji na povećanom metabolizmu glukoze koji pokazuju neoplastične stanice. Svi limfomi ne nakupljaju FDG, međutim, najčešći oblici (npr. difuzni B-velikostanični limfom, folikularni limfom), uključujući i Hodgkinov limfom (97-100% slučajeva), pokazuju velik FDG aviditet. Pri tome osjetljivost prelazi 80%, a specifičnost se kreće oko 90%, što nadilazi vrijednost CT-a. Općenito se smatra da indolentni limfomi slabije nakupljaju FDG, dok agresivniji histološki tipovi pojačano nakupljaju FDG. Kombinacijom metaboličke procjene, koju pruža FDG-PET, te morfološke procjene, koju omogućava CT, prevladavaju se ograničenja samog PET-a. Na taj način se dobiva visoko vrijedno dijagnostičko sredstvo koje omogućava istovremenu anatomsku i funkcionalnu evaluaciju. Viša osjetljivost PET/CT-a u usporedbi s CT-om, čini PET/CT korisnim sredstvom za određivanje stadija bolesti, kao i za procjenu remisije nakon liječenja. Interim PET/CT koji se izvodi u tijeku liječenja, nakon 1-4 ciklusa kemoterapije, može se koristiti za ranu procjenu odgovora. Brojna klinička istraživanja koja su u tijeku nastoje utvrditi može li se prediktivna vrijednost interim PET/CT-a uspješno koristiti za vođenje individualiziranog liječenja u svrhu poboljšanja ishoda liječenja te smanjenja toksičnosti terapije.Until recently, the evaluation of Hodgkin’s lymphoma patients following chemotherapy and radiotherapy was based on the assessment of morphological parameters, such as dimension of lymphomatous masses and enlarged nodes, determined with imaging investigations, the most important of which was total body CT. In quantifying response to therapy, CT provides no data regarding the residual viability of lesions. As a result of the inherent limitations of CT, innovative imaging modalities such as FDG-PET have been developed and increasingly introduces into clinical practice. That molecular diagnostic test relies on the evaluation of increased glucose metabolism shown by neoplastic cells. Not all lymphomas show FDG avidity, but most common types (e.g. diffuse large B-cell lymphoma, follicular lymphoma), including Hodgkin’s lymphoma (97-100% of all cases), are FDG avid with a sensitivity that exceeds 80% and a specificity of about 90%, which is superior to CT. In general, indolent lymphomas are considered less FDG avid than aggressive histologic types of lymphoma. Combining the metabolic assessment provided by FDG-PET and the morphological assessment provided by CT makes it possible to overcome the limitations of PET. The result is a diagnostic tool of high value which enables anatomical and functional assessment at the same time. Increased sensitivity of PET/CT, compared to CT, makes PET/CT a useful staging tool and end-of-treatment PET/CT assesses remission. Interim PET/CT made early during treatment, after 1-4 cycles of chemotherapy, can be used for early response assessment. Clinical trials are currently seeking to establish whether the predictive value of PET/CT can be successfully used to guide individual treatment to improve outcomes an reduce treatment related toxicity