But a big question still to be worked out is why people still succumbed to the disease.
"They all had progressive disease, which basically means they had developed mechanisms of resistance," Simon said. "We need to study what were these mechanisms of resistance and how can we counteract them, developing methods of either prevention of the emergence of resistance or treatment once resistance has emerged."
A second study in the same issue of the journal, conducted in East Asia, found that Iressa worked better than a chemotherapy regimen of carboplatin-paclitaxel as a first-line treatment for nonsmokers and former light smokers who also had non-small-cell lung cancer.
Here again, people with the EGFR mutation responded better to Iressa.
At one year, almost 25 percent of those on Iressa had continued without a recurrence, compared with nearly 7 percent in the other group.
"Overall, patients who got gefitinib [Iressa] had a longer time from the start of treatment to the worsening of disease," Simon said. "And it appeared that the drug's benefit was primarily seen in patients with EGFR mutations."
Overall survival, however, did not differ between the two groups, probably because many people started the other type of treatment after they had relapsed on the first treatment, Simon said.
The study was funded by AstraZeneca, which makes Iressa.
"This basically confirmed what we have thought, that in selected populations [light smokers or those who never smoked], those testing p
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