THERAPY RESPONSE IN NUCLEAR MEDICINE
Guest Editor: Bombardieri E. 

The Quarterly Journal of Nuclear Medicine 2003 March;47(1):8-13

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

PET-FDG as predictor of therapy response in patients with colorectal carcinoma

Dimitrakopoulou-Strauss A. ¹, Strauss L. G. ¹, Rudi J. ²

¹ Division of Oncological Diagnostics and Therapy German Cancer Research Center, Heidelberg, Germany 2 Department of Internal Medicine, Theresien Krankenhaus University of Heidelberg, Heidelberg, Germany

Aim. The pur­pose of ­this ­study was to eval­uate the prog­nostic ­value of quan­ti­ta­tive ­dynamic FDG PET ­studies in ­patients ­with met­a­stastic color­ectal ­cancer ­receiving ­FOLFOX (flu­o­rou­racil, ­folinic ­acid and oxa­lip­latin) chem­o­therapy.
­Methods. The eval­u­a­tion ­includes 28 ­patients ­with 55 metas­tases ­from pri­mary color­ectal ­cancer. Ref­er­ence for the FDG ­studies was the clin­ical ­response ­data, ­according to the WHO clas­sifi­ca­tion. ­Three ­response ­groups ­were ­defined: pro­gres­sive dis­ease (PD), ­stable dis­ease (SD) and par­tial ­response (PR). The FDG ­studies ­were accom­plished as ­dynamic ­series for 60 min. The eval­u­a­tion of the FDG ­kinetics was per­formed ­using the SUV, and ­fractal dimen­sion (FD) of the ­time ­activity ­curves ­based on the box ­counting pro­ce­dure (param­eter for the inho­mo­ge­neity of the ­tumors).
­Results. The ­median SUV as meas­ured in the ­tumor ­lesions ­prior to ­onset to ­FOLFOX was 3.15, in com­par­ison ­with 2.68 SUV ­after the ­first ­cycle and 2.61 SUV ­after the ­second ­cycle. Dis­crim­i­nant anal­ysis (DA) was ­used for the clas­sifi­ca­tion of the ­data ­into the 3 cat­e­go­ries. ­Both param­e­ters SUV and FD pro­vided 2 of the 3 “pre­dicted” cat­e­go­ries, ­namely PD and SD. It was pos­sible to cor­rectly clas­sify PR in ­only 10% of the ­patients, ­using the FD of ­both ­studies. Gen­er­ally, DA ­inclined to mis­clas­sify the ­data ­towards PD. ­Even the ­first PET ­study was pre­dic­tive ­with ­respect to ­therapy out­come (96% for PD and 47% for SD ­using ­only the base­line SUV). Metas­tases ­with a base­line SUV ­lower ­than 4.6 did not ­respond to ­FOLFOX chem­o­therapy. The com­bi­na­tion of SUV and FD of the ­first ­study ­lead to a cor­rect clas­sifi­ca­tion of 93% of PD and 60% of SD. ­Best ­results ­were ­obtained for the FD of the ­initial PET ­study (90% for PD and 75% for SD) as ­well as for the FD of ­both ­studies (77% for PD, 73% for SD, 10% for PR).
Con­clu­sion. Quan­ti­ta­tive, ­dynamic FDG-PET ­should be ­used pref­e­ren­tially for mon­i­toring ­patients ­with met­a­static color­ectal ­cancer ­receiving chem­o­therapy. ­Even the ­first FDG ­study ­prior to ­onset to chem­o­therapy is pre­dic­tive for the ­therapy out­come.