Washington, Sept 12 : Researchers at the Stanford University School of Medicine have found that computer models commonly used to decide who might benefit most from genetic testing under predicted the risk of breast cancer among Asian-American women.
Mutations in the BRCA1 and BRCA2 genes significantly increase the risk of breast and ovarian cancers, and women who learn they have these mutations are encouraged to seek more frequent cancer screening or may undertake other measures to reduce their cancer risk, such as preventive mastectomy or removal of the ovaries.
"We've been repeatedly surprised when Asian women who the models predicted would probably not have the mutations do in fact have them," said oncologist Allison Kurian, MD, of the university.
She showed that in a head-to-head comparison between whites and Asians, two of the most commonly used models failed in predicting the presence of mutations in almost half of the Asian women studied.
Kurian and her colleagues used two of the most widely used computer models, named BRCAPRO and Myriad II, to predict the presence of the mutations in 200 white women and 200 Asian-American women.
They sequenced the BRCA1 and BRCA2 genes of all of the study subjects and compared them to the models' predictions.
The researchers found that the models were highly accurate in predicting the presence of mutations in white women; one program identified 24 of the 25 women with BRCA1 or BRCA2 mutations and the other identified all 25.
However, both programs performed much worse in predicting the 49 Asian women in the study sample with mutations. One program predicted that only 25 of the 49 women would carry mutations, while the other recommended testing of 26 women.
"It's clear that these models are far from foolproof. These results emphasize the need for expert evaluation by a genetics professional to guide all clinical genetic testing," said Kurian.
The study was published online in the Journal of Clinical Oncology on Sept 8.