Letter in reply: Prognostic prediction by liver tissue proteomic profiling in patients with colorectal liver metastases

Abstract

We thank S Sabour for the interest expressed in our article [1] and we acknowledge his continu ous quest to improve the design of predictive studies through several letters to journal editors during the last years, to point out methodo logical issues, mistakes, misconceptions and misinterpretations [2][3][4].The results from our study showed that a single protein peak (7371 m/z) could differen tiate colorectal liver metastases patients from control patients with a sensitivity of 94.1% and a specificity of 100%. Also, with regard to colorectal liver metastases patients prognosis after surgery, we found that the algorithm that best differentiated favorable and unfavorable groups only needed two protein peaks (2970 and 2871 m/z) to discern prognosis with a sensitivity of 100% and a specificity of 90%. These promising results, which S Sabour seems to minimize, come from a preliminary study, are not at all clinically definitive (i.e., vali dated) and should thus encourage further validation studies as we clearly wrote in the 'Discussion'. We were fully aware of these design limitations from the initial moment we designed the study and that was the reason to necessarily include some words of caution in the 'Discussion'. Moreover, among other rea sons for this prudent statement we can include that some preliminary studies can give mis leading results without validation of the ini tial prediction (as S Sabour rightly points out) but also because validation studies (and not exploratory or preliminary studies like ours) are the ones that have the power to ascertain the strength of the relation and properly study the interaction between variables.