Comments on the letter of Toncheva and Nacheva concerning our paper “Latent chromosomal instability in cancer patients”

Abstract

The extensive literature on chromosome studies in cancer patients indicates that chromosomal instability is a basic genetic event that explains diverse characteristics of neoplasias, such as predisposition or clonal evolution (Nowel 1986). It is also known that the results obtained with the same protocol can vary greatly and depend, among other things, even on seasonal differences in the break frequency (Mattei et al. 1979).The data provided by the authors of the Letter to the Editor, Toncheva and Nacheva, are an example of this. In two successive evaluations, interestingly denoted as "our study" and "the previous one", they note differences in the chromosomal/chromatid breaks in cancer patients of more than 10% and state that the results of the second study are in agreement with those published by other authors and "contradict" our observations. It should be mentioned that the second "more reliable" study is performed on G-banded chromosomes, notwithstanding the fact that RV staining has previously revealed a higher percentage of breaks and that the results are statistically highly significant (P<0.001). More questions have to be addressed to the selection and heterogeneity of the material and the lack of information about histological type, clinical stage (TNM classification) or the relatively young age of the patientsall below 50 years. As an example, the peak age at presentation of colorectal cancer is around 65 years and of urinary bladder carcinoma between 59 and 65 years. A younger age generally implies the involvement of additional genetic factors in tumorigenesis and thus increased chromosomal instability. In this respect, our attention is attracted by the group of familial adenomatous polyposis colli (APC) patients in which, at the average age of 39 years, only tubular and tubulovillous adenomas are observed, instead of the expected progression towards villous adenomas, dysplasia and carcinomas. The diagnosis of LETTER TO THE EDITOR