A case-control study with oral squamous cell carcinoma (OSCC) patients from Instituto do Câncer do Estado de São Paulo (ICESP) and healthy volunteers. In this study, it will be collected saliva samples from both groups that will be submitted to sequencing analysis to evaluate the frequency of ALDH1b1 and ALDH2 polymorphisms in the Brazilian population. Also, correlate OSCC risk to alcohol consumption or smoke, by applied questionnaires.

According to the World Health Organization (WHO), in 2016 there were 3 million deaths worldwide from alcohol abuse. ALDH1b1 and ALDH2 proteins are involved in the alcohol metabolism promoting the conversion of acetaldehyde to acetate. The genes that encode these proteins have genetic variants, also called polymorphisms, that can promote changes in their functions such as the accumulation of acetaldehyde in the body, resulting in facial flushing, tachycardia and headache. Studies reported the correlation between alcohol consumption and/or smoking and these polymorphisms to a higher risk for head and neck cancer, including oral squamous cell carcinoma (OSCC). The aim of this study is to determine the frequency of the ALDH1b1 and ALDH2 polymorphisms in the Brazilian population, in addition to estimating the risk for OSCC among those with polymorphisms. For this, unstimulated saliva samples will be collected from OSCC patients and healthy volunteers. All study participants must complete two questionnaires on alcohol consumption, smoking and disease history. Saliva samples will be collected using the DNA/RNA Shield Saliva Collection Kit and stored at -20ºC. The DNA will be extracted, quantified by the Nanodrop equipment and amplified by the polymerase chain reaction (PCR), using specific primers for each of the genetic variants. The PCR product will be sent to the Sequencing Service of the Centro de Pesquisas sobre o Genoma Humano e Células-Tronco/IBUSP, where the Sanger sequencing technique will be performed and the results will be analyzed in the ICB-USP laboratory. For the group of patients, medical records will be monitored to correlate clinical data and genetic variants with overall survival. These data will allow the characterization of the genetic variants of ALDH1b1 and ALDH2 in the Brazilian population and support the development of future public policies to reduce the main risk factors for OSCC, especially among those with these genetic variants.

Inclusion Criteria:

• OSCC diagnostic for case group
• Able to read and sign the consent form.
• Able for saliva collection.
• Able to understand the applied questionnaires.

Exclusion Criteria:

• Unable to read and sign the consent form.
• Unable for saliva collection.
• Unable to understand the applied questionnaires.
• OSCC patient's companions for healthy volunteers.

OSCC patients (n = 60) and healthy volunteers (n = 240) matched by age and sex.