Recent research revealed that little breast tumors of the type known as HER2 positive are more likely to come back even after being cured by surgery. Researchers said that women with these kinds of tumors should also be treated with drugs such as Genentech Inc.'s Herceptin.

Lead researchers, Dr. Ana M. Gonzalez-Angula of the M.D. Anderson Cancer Center in Houston said: "Most physicians do not treat these small tumors with Herceptin."

Research team looked at records on 1,315 such patients. Analysis of these records revealed that the 10 percent who had high levels of a protein known as HER-2 had three times the risk of suffering a recurrence than did women with less HER-2. The study also showed that only 77 percent of those with high HER-2 levels were alive and cancer-free five years after treatment versus 94 percent of the others.

Gonzalez-Angula said that after five years, 23 percent of patients with tiny tumors one cm (half an inch) or smaller whose cancer was HER2 positive had tumors come back after surgery.

Research team concluded that HER2-positive tumors had been more difficult to treat but Herceptin, known generically as trastuzumab, is a genetically engineered antibody -- an immune system molecule -- that homes in on that particular mutation.