Associação entre os hábitos alimentares e as concentrações séricas das vitaminas A e E com os preditores de prognóstico histopatológico do carcinoma papilífero da tireoide

Abstract

Thyroid cancer (TC) is the most common malignancy of the endocrine system. According to last estimates from the Brazilian National Cancer Institute (INCA), this neoplasm is expected to reach 9610 people in Brazil by the end of 2018, and the largest number of cases is expected to occur in the Northeast region (Ceará, Paraíba and Rio Grande do Norte). Papillary thyroid carcinoma (PTC) accounts for about 70% of TC cases, and considering that the rate of incidence varies in different parts of the world, modifiable risk factors may play an important role in TC carcinogenesis. Moreover, alterations in microRNAs (miRNAs) expression may also be part of TC risk factors. In addition, the frequent consumption of certain foods has also been associated with the progression of malignant tumors. Experimental and clinical studies have shown that antioxidant vitamins can inhibit the development and progression of cancer, thus the biochemical status of vitamins A and E have emerged as potential markers of risk for genesis and evolution of the disease. Therefore, the present study aimed to investigate the current knowledge on modulation of miRNA expression induced by vitamins A and E in TC, and the association of dietary habits and serum concentrations of vitamins A and E with histopathological prognostic factors of CPT. For this, a systematic review was conducted following the guidelines "The Prism: Statement for Reporting Systematic Reviews and Meta-Analyzes of Studies That Evaluate Health Care Interventions: Explanation and Elaboration". Furthermore, weekly eating habits before TC diagnosis were evaluated using a Food Frequency Questionnaire (FFQ) developed by the Elsa-Brazil study. Serum retinol and serum αtocopherol were measured in three times liquid chromatography: one before thyroidectomy and two after thyroidectomy of PTC patients. The results showed that evidence of changes in miRNA expression induced by vitamins A and E in TC are scarce, however, vitamin A appears to be relevant in the modulation of miRNAs in other tumors. In addition, weekly food intake > 1/week of couscous/farofa and/or margarine/vegetable cream may increase the risk of CPT patients present extrathyroidal extension (p = 0.021 and 0.004 respectively), while beef intake > 1/week may increase risk of extrathyroidal extension (p = 0.040) and lymph node metastases (p = 0.046). Regarding serum concentrations of retinol and α-tocopherol, high serum retinol levels may be associated with a lower predisposition to develop angiolymphatic invasion, and lymph node metastases (p = 0.027 and 0.015 respectively), and PTC patients with extrathyroidal extension or angiolymphatic invasion tend to have post-operative vitamin E concentrations lower than the preoperative. We suggest that both food intake and vitamin A status and may be relevant in predicting histopathological outcomes of CPT. Thus, future studies on the modulation of miRNAs induced by vitamin A in TC are necessary.