That's the gist of this Forbes.com article: Early, Unproven Findings Changing Doctors' Practice. From the article:
That's the conclusion of a study in the March 15 issue of the Journal of the National Cancer Institute that discovered early findings presented at a national cancer conference rapidly changed the way doctors treated breast cancer -- even though the trial needed much more data and time to offer up conclusive results.
Luckily for American women, the completed study -- published years later in a medical journal -- ended up confirming the effectiveness of the drug Taxol against a specific type of breast malignancy.
But the authors of the new study warn that many other treatments -- for example, cox-2 painkillers or the lung cancer drug Iressa -- looked just as promising during the early days of trials, only to prove useless or even harmful as more complete data emerged over time.