Early restaging positron emission tomography with 18F-fluorodeoxyglucose in aggressive non-Hodgkin's lymphomas: Is it too easy to be true? [3]

In summary, this paper outlines the well-known importance of early response to chemotherapy [3] on the basis of modern staging techniques such as PET. However, the authors' suggestions seem to be too enthusiastic and some doubts regarding the role of early PET restaging appear justified. In fact, in this study, a comparative analysis of midtreatment PET versus conventional diagnostic methods was not performed. Thus, it is difficult to draw any conclusion on the predictive role of PET compared with standard diagnostic approaches. In other words, how many patients could be defined as non-complete responders at midtreatment by means of more standard and less expensive techniques, such as ultrasound, CT (computed tomography) scan and maybe clinical evaluation? Probably all the eight progressing patients as well as a proportion of those in partial remission. Thus, it is possible that the differences in PFS, as reported in figure 2 of the paper, could be less impressive, even if still significant, if patients with resistant disease at midtreatment assessed independently of PET were removed from the analysis. The prognostic role of PET could be further reduced to only patients that appear to be in CR at midtreatment restaging by conventional procedures. Even if PET is a promising prognostic tool in restaging lymphoma patients, its use as the only staging and restaging method has yet to be defined, and appropriate studies to evaluate its diagnostic and prognostic role in lymphomas are of high priority.