Department of Clinical Oncology and Hematology, Istituto Clinico Humanitas, Rozzano, Milano, Italy
*E-mail: monica.balzarotti@humanitas.it
In the September 2002 issue of Annals of Oncology, Spaepen and coworkers [1] reported the prognostic value of early restaging positron emission tomography with fluorine-18 fluorodeoxyglucose [(18F) FDG PET] in 70 consecutive patients with aggressive non-Hodgkins lymphoma (NHL) treated with anthracycline-containing regimens. Among 33 cases with positive midtreatment PET, no patients maintained a durable complete remission (CR). Conversely, all cases with durable CR had negative midtreatment PET. Only five of 37 with previously negative PET relapsed, and one with mantle cell lymphoma did not achieve CR because of persistent bone marrow disease undetectable by PET. The differences in terms of progression-free survival (PFS) and overall survival (OS) among these two groups are highly statistically significant (P <1 x 105 for both parameters). On the basis of Cox regression analysis, the authors conclude that midtreatment PET is a stronger prognostic factor than the International Prognostic Index [2] for both PFS and OS.
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.
M. Balzarotti* M. Magagnoli & A. SantoroDepartment of Clinical Oncology and Hematology, Istituto Clinico Humanitas, Rozzano, Milano, Italy (*E-mail: monica.balzarotti@humanitas.it)
References
1. Spaepen K, Stroobants S, Dupont P et al. Early restaging positron emission tomography with 18F-fluorodeoxyglucose predicts outcome in patints with aggressive non-Hodgkins lymphoma. Ann Oncol 2002; 13: 13561363.
2. The International Non-Hodgkins Lymphoma Project. A predictive model for aggressive non-Hodgkins lymphoma. N Engl J Med 1993; 329: 987994.
3. Armitage J, Weisenburger D, Hutchins M et al. Chemotherapy for diffuse large-cell lymphoma: rapidly responding patients have more durable remission. J Clin Oncol 1986; 4: 160164.[Abstract]