After five years, roughly 96 percent of both groups were alive, and most deaths were not from breast cancer. About 1 percent of those given radiation had cancer recur in the treated breast versus 4 percent of those who skipped radiation.
For every 100 women given radiation, “one will have a recurrence anyway, four will have a recurrence prevented, but 95 will have had unnecessary treatment,” Kunkler said. Since radiation did not affect survival or the risk of cancer spreading, skipping it “is a reasonable option.”
Doctors are unsure how to treat women with small tumors involving the gene that the drug Herceptin targets. Those tumors are low risk because they’re still confined to the breast, but high risk because the gene is thought to make them more aggressive. Some women get heavy-duty chemo, including drugs that can damage the heart.
Dr. Eric Winer of the Dana-Farber Cancer Institute in Boston led a study of 406 women given “light chemo” — paclitaxel plus Herceptin for 12 weeks, followed by nine months of Herceptin alone. More than three years later, only four had cancer recur in the same breast, and two had recurrences in other places.
“This is likely to become a new standard,” Winer said.
The cancer conference is sponsored by the American Association for Cancer Research, Baylor and the UT Health Science Center.