Women with small breast tumors that seem cured after surgery have a substantially increased risk for relapse, U.S. researchers report. The researchers presented their data during a teleconference Friday at the annual San Antonio Breast Cancer Symposium in Texas.
The researchers said women who have breast cancer tumors known as HER2-positive, even those a centimeter or less in diameter, might need extra treatment with drugs such as Genentech Inc.'s Herceptin. These treatments aren’t usually recommended for women whose tumors are smaller than 1 centimeter. HER2-positive breast cancer tests positive for a protein called human epidermal growth factor receptor 2.
For the study, Texas researchers looked at records on 1,315 patients with small tumors, 1 centimeter in diameter or smaller and found that the 10 percent who had HER2-positive tumors had three times the risk of suffering a recurrence than did those with HER2-negative disease. The five-year recurrence was 23 percent for those with HER-2 positive disease, compared to about 6 percent for those with HER-2 negative disease. The participants in the study had been treated at the University of Texas M.D. Anderson Cancer Center in Houston or at two European hospitals in the 1990s.
Herceptin, known generically as trastuzumab, is a genetically engineered antibody that targets the particular mutation found in HER2-positive tumors. The new findings may lead doctors to rethink HER-2's importance and whether to more widely recommend Herceptin, said the study's leader, Dr. Ana Gonzalez-Angulo of M.D. Anderson.
A second study presented at the annual San Antonio Breast Cancer Symposium, in Texas, has shown that estrogen therapy may cause cancer cells to grow slow. Estrogen-receptor (ER)-positive breast cancer accounts for the majority of breast cancers diagnosed each year. About 75% of breast cancers are estrogen-receptor positive. Cells with estrogen receptors grow and multiply when estrogen attaches to their receptors. These types of cancers respond well to hormonal therapy.
