Polygenic risk scores (PRS) derived from multiple single-nucleotide polymorphisms (SNPs) associated with breast cancer risk in populations of women of predominantly European ancestry were also predictive of the risk of breast cancer in Latina women, according to results of a case-control study reported in the Journal of the National Cancer Institute.
Genome-wide association studies have revealed over 180 SNPs associated with increased breast cancer risk. These SNPs have been combined into PRS that predict breast cancer risk based on variation in these multiple genetic loci. Nevertheless, these tools have been primarily developed and evaluated in populations of women with European ancestry, and data are limited on their performance in non-European populations, such as Latinas, that include individuals with varying amounts of Indigenous American, European, African, and Asian ancestry.
In this study, 2 PRS, based on 180 SNPs and 71 SNPs, were evaluated for their ability to predict the risk of invasive breast cancer in women pooled from 8 studies who identified as Latina with varying degrees of Indigenous American and European ancestry. The main analysis of the 180-SNP PRS included 4658 women classified as cases with invasive breast cancer and 7622 control patients, whereas the respective numbers of these patients included in a secondary analysis of the 71-SNP PRS were 5697 and 7927.
A key finding from this study was that both PRS were predictive of breast cancer risk in this Latina population. Specifically, multivariable logistic regression analyses adjusted for study and genetic ancestry showed that the odds ratios of breast cancer per SD increment of PRS relative to the mean in controls was 1.58 (95% CI, 1.52 -1.64; P <.001) and 1.51 (95% CI, 1.46 to 1.56; P <.001), for the 180-SNP and the 71-SNP PRS, respectively.
Of note, these results did not vary substantially across groups of Latina women with varying degrees of Indigenous American ancestry.
“Though our findings suggest that the PRS can predict breast cancer risk in Latinas, they do not nullify the prospect of disparities in genetic discovery research,” the study authors noted.
They further commented that “as genetic association studies identify more rare variants, those discovered in European populations will be less generalizable to other populations. Thus, high-quality genetic studies in non-European populations remain a priority.”
Shieh Y, Fejerman L, Lott PC, et al. A polygenic risk score for breast cancer in US Latinas and Latin American women. J Natl Cancer Inst. 2020;112:590-598.