Why useful genetic testing is hard.
The NZ Herald reports (from a Cancer UK press release): A single genetic fault in a gene that normally helps the body to repair its DNA increases a woman’s risk of ovarian cancer six-fold, a study has found. That sounds as if it might be useful as a way of detecting women at high risk, until you look at the numbers in more detail.
In the UK, where the study was conducted, about 6500 women per year are diagnosed with ovarian cancer, and 40-50 of these women will have the genetic fault. New Zealand has about 15 times fewer people than the UK, so that would be about 3 women per year in the whole country who develop ovarian cancer because of this genetic variant.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »