They are also setting up longer studies.
The researchers suggested that longer studies might find even larger problems.
Longer studies, he said, are needed to show whether the lipid benefits last and to find out whether low-carbohydrate diets carry other risks.
Both were early studies, and researchers emphasized that more definitive results would come from larger, longer studies that were under way.
Longer studies comparing the new technique with standard therapy are needed to confirm that it is equally effective in curing the cancers.
But those figures are based on just three years of follow-up, and it is possible that longer studies will show otherwise.
But longer studies are needed before the surgery, bilateral mastectomy, can be presented as anything but an option for women with the gene, researchers said.
With the withdrawal of Vioxx, the F.D.A. is considering whether longer studies will be needed for COX-2 inhibitors -- both those on the market and those still under development.
So they expanded the project even further, into two longer studies, broader in remit, and this time people who thought they'd had a vitamin pill were less likely to exercise and less likely to choose healthier food.
Many of the writers have published longer studies of the same people, or books that in some way touch on the figures they discuss.
The technique of PET was replaced with the more flexible technique of functional magnetic resonance imaging (fMRI), which allowed scientists to study people's brains without the use of the risky radioactive tracers, and to conduct longer studies that collected more data and yielded more reliable results.
