Can Isotretinoin Induce Cytogenetic Damage in Oral Cells?

For treating acne vulgaris, isotretinoin has been used with great success in recent decades [1]. However, a risk assessment in different cells and/or tissues is mandatory to evaluate the risks of cellular toxicity caused by this treatment [2]. Studies investigating the genotoxicity of isotretinoin are scarce in the literature. In the paper recently published in the Journal of Oral Pathology and Medicine titled “Cytological and genotoxic effects of systemic isotretinoin on oral mucosa cells (https://doi.org/10.1111/jop.70048)” Uslu and Donmez [3] detected increased levels of micronuclei in buccal cells of individuals exposed to isotretinoin. To the best of our knowledge, this is the first study to reveal isotretinoin as a genotoxic agent in oral cells. However, further analysis is necessary to accurately interpret these findings. First, Table 1 presents a comparison of participant ages by gender but it is confusing. For example, the subgroups “Woman control group,” “Woman study group,” “Man control group,” and “Man study group” appear twice in Table 1. Additionally, the respective values for the “Woman study group” and “Man study group” differ (mean and/or standard deviation). This requires further clarification. In addition, it was stated that “Among the participants, six participants (30%) reported using the systemic isotretinoin for > 6 months, while 14 participants (70%) reported using it for > 6 months.” These data should be demonstrated in Table 1, since they are very important for understanding the manuscript with accuracy. In the context of genotoxicity evaluation, it is imperative to adhere to some parameters in genotoxicity assays to ensure proper evaluation and, consequently, credible results [4]. For instance, the micronucleus assay necessitates compliance with certain requisites. This is done to uphold the quality of outcomes. In this regard, some factors are pivotal considerations, such as the cytotoxicity test, the minimum number of evaluated cells (2000 for buccal cells), and the use of a specific DNA stain [4]. Consequently, studies should adhere to the recommendations of the Micronucleus Assay Expert Group for high research quality [4]. In this study, the authors state that “Following Feulgen staining, a total of 1000 cells were counted in each preparation for the evaluation of micronucleus”. The small number of cells evaluated in this study interferes with the quality of the results, especially when comparing acute and chronic treatment with isotretinoin. In Material and Methods, it was purposed to identify the presence of micronucleus, nuclear budding and binucleation when performing the micronucleus assay, but these data are missing. The nuclear buds were not evaluated in the manuscript and binucleation was detected in the cytological analysis using Pap Smear (Table 2). How did the authors standardize “cell width” and “cell length” for cytomorphometric analysis? In our opinion, these data were collected empirically without any reproducibility (as demonstrated in Figure 1). Regarding the micronucleus analysis, the authors presented the number of micronucleus (MN score) and the presence of micronucleated cells (MNed cells). What is the difference between these parameters, and what is the distinct biological significance of each one? This needs to be clarified in the manuscript. In Discussion, it was stated that “The lack of a significant difference in MN counts between shorter (< 6 months) and longer (> 6 months) treatment durations suggest that these genotoxic effects may occur early in isotretinoin therapy”. These data must be presented in the manuscript, not in a supplementary file, since they are crucial for accurately interpreting the data. We believe such comments are useful for correctly understanding this important paper, which is the first to evaluate the systemic effects of isotretinoin on oral cells. Writing the letter: all authors. The authors acknowledge research grants received from CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Grant Number #001) for productivity fellowship (P.R.C., J.N.d.S. and D.A.R.). The authors have nothing to report. The authors have nothing to report. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.