Study may have ‘cracked the code’
“What’s exciting is that I think we kind-of ‘cracked the code’ to some extent of how to do this across diseases for all ancestries,” Thomas P. Slavin, MD, chief medical officer at Myriad Genetics, said in an interview. “The adaptation for breast cancer risk stratification and the new panel [is] for breast cancer across all ancestries, but what we developed is something that could be used across diabetes, or colon cancer, or anything.”
He explained that they realized that “for each one of these little hot spots” in the SNPs, “that make one person different from another, you really need to find out where in the world that originated from. So, if you have genetic ancestry on an individual, you can say this spot in the genome has more of an African ancestry to it, or a European ancestry, and then you can weight it appropriately by the population.”
Dr. Slavin said that standard PRSs that simply add up SNPs are “pretty good” and “add a lot” to risk stratification, “but to fine-tune it a little bit and make the best risk model, you really do need to bring in clinical and family history factors.”
Montserrat García-Closas, MD, DrPH, deputy director of the cancer epidemiology and genetics for the National Cancer Institute, said the study is of interest, but “does not give information on how ancestry was considered in the models used to derive the scores.” She also cautioned that the method used in the study to calibrate the model seems “to mean a comparison of scores, rather than comparing the observed and expected risk in prospective cohorts by ancestry groups. This would be a way to estimate bias in risk prediction by ancestry.”
Nevertheless, Dr. García-Closas said the degree of risk reclassification seen with the combined risk score is as expected and pointed to recent work by her and her colleagues in which they tested an integrated model incorporating classical risk factors and a 313-variant PRS to predict breast-cancer risk and achieved similar results.
Several study authors disclosed ties with Myriad Genetics, as well as AstraZeneca, Bristol Myers Squibb, Clovis Oncology, Helix BioPharma, Konica Minolta, Ambry Genetics, Invitae, Stryker, GAIL, Phenogen Sciences, Novartis, Pfizer, CancerIQ, Tempus, 54gene, Color Genetics, Roche/Genentech, ImpediMed, Prelude Therapeutics, BD, Agendia, Targeted Medical Education, Cerebrotech Medical Systems, Integra LifeSciences, Puma Biotechnology, GeneDX/BioReference, Change Health Care, Research to Practice, Clinical Care Options, Physician Education Resource, and Daiichi Sankyo.
The headline for this article was updated on 1/6/22.