Dados do Trabalho

Título

RISK FACTORS FOR ADENOMA AND COLORECTAL CANCER IN A BRAZILIAN SCREENING POPULATION

Introdução

Colorectal cancer (CRC) is the second most common cancer in Brazil. A Fecal Immunochemical Test (FIT)-based CRC screening program was implemented in the region of Barretos. Risk factors and the prevalence of baseline neoplasia are important features for guiding a screening strategy.

Objetivo

This study aims to measure screening outcomes (adenoma, advanced adenoma (AA), and cancer) and associate with risk factors and genetic ancestry.

Método

This cross-sectional analysis included subjects from 50 to 65 years from the Barretos' screening program. The ancestry components were analyzed using a multiplex PCR of 46 ancestry informative markers, based on insertion-deletion polymorphisms. A binary logistic regression model was used to associate sociodemographic factors and outcomes. The excess risk by municipality was analyzed considering the number of cases of CRC, adenomas (early and advanced) and participants’ risk factors.

Resultado

From November 2017 to March 2020, 2946 asymptomatic individuals were enrolled, being 83.0% females (mean age of 57.1 ± 4.5 years), mainly from São Paulo State (79.1%). Self-reported skin color revealed 56.8% white, 36.6% brown, 5.8% black, and 0.7% yellow, and 69.9% had < high school. The genetic ancestry revealed a mean proportion of 67.9% for European ancestry, 17.0% for African, 7.3% for East Asian, and 7.8% for Native American. A significant association of genetic ancestry and self-reported skin colors (p<0.001) was found. Current/former smokers comprised 41.9%, 31.2% alcohol drinkers, 73.3% exercised < 3x/week, and 71.9% had a BMI > 25kg/m². 82.8% participants returned the FIT kits, the inadequate FIT rate was 2.5%, and the positivity was 6.2%. The follow-up colonoscopy compliance was 90.5%, and the cecal intubation was successful in 99.0%. The PPV was 64.1% for adenoma, 20.1% for AA, and 3.7% for CRC. Five cancer patients had stage I or II. Male gender (OR=2.94, 95% CI 1.06-8.17), overweight (OR=5.40, 95% CI 1.42-20.52), alcohol (OR=3.86, 95% CI 1.38-10.78), fried foods (OR=2.82, 95% CI 1.02-7.78) were associated to AA. Non-white skin color (OR=2.83, 95% CI 1.11-7.17), overweight (OR=3.54, 95% CI 1.21-10.30), and eggs/milk (OR=5.25, 95% CI 1.32-20.80) were associated to early adenoma. Around one third of the municipalities presented relative risk up to 2.0. The municipality of Guaíra presented higher excess risk for most factors.

Conclusão

CRC detected in early stages corroborates the role of screening programs increasing the early diagnosis. Lifestyle risk factors were significantly associated with high and low-risk precursor lesions. Overall, our results in an admixed population can contribute to delineating strategies and a targeted CRC screening program to improve CRC prevention and control.

Palavras-chave

Colorectal cancer; adenoma; screening; FIT