AUTHOR=Durães Ronilson Oliveira , Berardinelli Gustavo Noriz , da Costa Allini Mafra , Scapulatempo-Neto Cristovam , Pereira Rui , Oliveira Marco Antônio , Guimarães Denise Peixoto , Reis Rui Manuel TITLE=Role of Genetic Ancestry in 1,002 Brazilian Colorectal Cancer Patients From Barretos Cancer Hospital JOURNAL=Frontiers in Oncology VOLUME=10 YEAR=2020 URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2020.00145 DOI=10.3389/fonc.2020.00145 ISSN=2234-943X ABSTRACT=

Background: Colorectal cancer (CRC) is the third most frequent and the second deadliest cancer worldwide. The ethnic structure of the population has been gaining prominence as a cancer player. The purpose of this study was to determine the genetic ancestry of Brazilian CRC patients. Moreover, we intended to interrogate its impact on patients' clinicopathological features.

Methods: Retrospective observational cohort study with 1,002 patients with CRC admitted from 2000 to 2014 at Barretos Cancer Hospital. Following tumor DNA isolation, genetic ancestry was assessed using a specific panel of 46 ancestry informative markers. Survival rates were obtained by the Kaplan–Meier method, and the log-rank test was used to compare the survival curves. Multivariable Cox proportional regression models were used to estimate hazard ratios (HRs).

Results: We observed considerable admixture in the genetic composition, with the following average proportions: European 74.2%, African 12.7%, Asian 6.5%, and Amerindian 6.6%. The multivariate analysis for cancer-specific survival showed that clinical stage, lymphovascular invasion, and the presence of recurrence were associated with an increased relative risk of death from cancer (p < 0.05). High African proportion was associated with younger age at diagnosis, while high Amerindian proportion was associated with the mucinous histological subtype.

Conclusions: This represents the larger assessment of genetic ancestry in a population of Brazilian patients with CRC. Brazilian CRC patients exhibited similar clinicopathological features as described in Western countries.

Impact: Genetic ancestry components corroborated the significant admixture, and importantly, patients with high African proportion develop cancer at a younger age.