Reply to “Early interim 2-(1)fluoro-2-deoxy-D-glucose positron emission tomography is prognostically superior to peripheral blood lymphocyte/monocyte ratio at diagnosis in classical Hodgkin’s lymphoma” Haematologica 2012;97(6):e21–3

We read with interest the article by Romano et al.1 entitled “Early interim 2-(1)fluro-2-deoxry-D-glucose positron emission tomography is prognostically superior to peripheral blood lymphocyte/monocyte ratio at diagnosis in classical Hodgkin’s lymphoma”. In this study, the authors compared the absolute lymphocyte/monocyte count ratio at diagnosis (ALC/AMC-DX) recently published by us1 with the interim 2-(1)fluro-2-deoxy-D-glucose positron emission tomography (PET-2) in a cohort of 115 classical Hodgkin’s lymphoma (cHL) patients. In this study, the authors were able to correlate prognosis with ALC/AMC-DX ratio. However, in this cohort of 155 cHL patients, the predicting value of ALC/AMC-DX was inferior to PET-2 in predicting 2-year progression-free survival and disease-free survival. Only 10 of the 115 patients presented with an ALC/AMC-DX ratio of less than 1.1 and 91.3% presented with an ALC/AMC-DX ratio equal or greater than 1.1.2 The authors raised a valid question with regard to calculating different cut-off points in different series of the ALC/AMC-DX ratio. This is a very important assessment because either data-oriented or outcome-oriented statistical methods to identify cut-off points from continuous variables are limited by the sample inter-variability. This limitation is well-described by Buettner et al.3 who stratified random samples of 5,093 melanoma patients from six artificial distributions to identify the best cut-off points of tumor thickness. Each random sample distribution provided different cut-off points. This is further validated by the fact that other groups are making similar observations of the prognostic ability of the ALC/AMC-DX ratio with different cut-off points in confirmation of our findings2 and those of Romano et al.1 Another important point to address is that even though statistical methods are used to identify new prognostic bio-markers, it is important that these new bio-markers are biologically sound to help us understand and improve clinical outcomes. This article by Romano et al. continues to add more information to the growing medical literature of the impact of the peripheral blood absolute lymphocyte count and absolute monocyte count on the survival of cancer patients.4