| Resumo: |
Squamous cell carcinoma (SCC) represents more than 90% of all oral and oropharyngeal malignancies. Involved in this process, there are extrinsic factors, such as the consumption of smoked and chewed tobacco, the consumption of alcoholic beverages, human papillomavirus infection and chemical-physical stimuli; and there are intrinsic factors, such as nutritional deficiencies and genetic conditions. In view of the relationship of alcohol ingested as a promoter of oral carcinogenesis, the effect of long-term topical use of substances containing alcohol is debated in the literature and the possible association of the use of mouthwashes with oral cancer is based on the fact that these products are of free sale with some compositions having high alcohol content. However, the published meta-analyzes on this subject, to the extent that they were based only on the biological plausibility of the cytotoxic effect of the alcohol content of the rinses, were unable to estimate a statistically significant weighted measure. Allied to this, until now, no study seems to have examined the effect of non-alcoholic mouthwashes, which suggests the possibility that other components of the formulations also contribute to the risk, altering the diversity of oral bacteria and causing cellular damage. That said, this work was proposed in order to update the published meta-analyzes, estimating a measure of the combined effect of the observational studies that present the outcome of oral cancer. This systematic review and meta-analysis was reported according to the recommendations of the PRISMA checklist and had its protocol registered on the PROSPERO website under the identifier number CRD42020143307. The search strategy used was with the acronym PECO. In the bibliographic search, 5.696 records were identified in indexed databases and gray literature, without restriction of time and language. After excluding duplicates, 4.711 titles and abstracts were read. Of these, 22 studies were selected to read the full text and 10 included in our review together with 01 article identified in the search for reference lists. The assessment of the risk of bias in the studies included in the review was carried out independently, by two reviewers, using the Newcastle - Ottawa scale (NOS) for case-control studies, and 05 out of 11 studies were found to have a low risk of bias and 06 with moderate risk of bias. For the meta-analysis, 09 case-control studies were selected, which went through the evaluation of the quality of the evidence by GRADEpro GDT Guideline Development Tool, proving to be of very low quality. In the grouped analysis, 10 measurements from the 09 studies were summarized using the random effects model, using the DerSimonian-Laird method. As a result, we obtained an association between the use of mouthwashes and oral cancer (OR = 1.46; 95% CI: 1.12-1.91). When stratifying by frequency of use, the association was not maintained among those who used it less than once a day (OR = 0.91; 95% CI: 0.61-1.36), but remained significant in the category of one or more times a day (OR = 1.74; 95% CI: 1.25-2.43), suggesting a possible dose-response. It was not possible to carry out a subgroup analysis according to the alcohol content of the mouthwashes, so that we could assess whether the substances present in their formulations are important for oral cancer independently of alcohol. Meta-regression was performed and the proportion of cases and controls contributed 33% to the explanation of heterogeneity. Publication bias was analyzed using the Egger regression test and was found to be statistically significant (p = 0.081). The present systematic review and meta-analysis demonstrates that the frequent use of mouthwashes was associated with a 46% higher chance of oral cancer when compared to non-use and we suggest that this relationship could be explained not only by the alcohol content, but also by the contribution antibacterial compounds, which reinforces the need for further studies with these data to properly clarify the association between this exposure and this outcome. |
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