SCIENCE / MEDICINE : Breast Cancer Survival Rate May Double, Study Finds : Treatment: A combination of bone marrow transplants and high doses of drugs is credited for 58% of patients being free of the disease after one year.
A combination of bone marrow transplants and very high doses of anti-cancer drugs may be able to double the survival rate of patients with advanced breast cancer, a Boston researcher reported last week.
Dr. Karen Antman, an associate professor of medicine at Harvard Medical School, said that 58% of 259 patients given the new treatment regimen at 13 medical centers were free of cancer at the end of one year. Normally, fewer than 30% of patients given conventional therapy show similar success.
The normal period of survival for patients with advanced breast cancer is only two years, but some women in the study are still alive after four, five and six years, she reported at a cancer symposium in Tokyo.
An estimated 150,000 women in the United States contract breast cancer each year. If the cancer is confined to the breast at the time of detection, surgery, radiation and chemotherapy are effective and the five-year survival rate is now 90%, according to the American Cancer Society.
If the cancer has spread locally, the five-year survival rate drops to 68%, and if it has spread to other organs, the rate plummets to only 18%. An estimated 44,000 women will die of the disease in 1990.
The problem with such “disseminated” breast cancer is that the cancer cells become resistant to the drugs that are normally used to kill them. Laboratory studies show, however, that very high doses of the drugs will kill virtually all of the malignant cells before they have time to develop resistance. “The higher the dose, the less likelihood of resistance and the more tumor cells that are killed,” Antman said.
But those high doses also kill the bone marrow that is necessary to produce life-sustaining blood cells.
To overcome this problem, Antman and other researchers are using a technique known as autologous bone marrow transplantation. At the beginning of treatment, about one quart of the patient’s bone marrow is removed through a thin needle inserted in the hip bone. The marrow is treated with a small amount of the anti-cancer drug to remove stray cancer cells and frozen.
The patient is then treated for four days with massive doses of anti-cancer drugs, about 10 times the amount normally used. This kills the cancer cells in the body, as well as the remaining bone marrow.
Three days later, the frozen bone marrow is thawed and infused into the patient through a vein. The patient must be kept in strict isolation for at least two weeks to protect her from infections until the bone marrow, which is the source of disease-fighting white blood cells, becomes sufficiently re-established to protect the patient.
According to Antman, two new developments have made high-dose chemotherapy medically and physically easier, less expensive and safer. The first is the use of human growth factors--produced by genetic engineering techniques--to speed the recovery of white cells needed to control infection and of platelets essential for blood clotting.
The second involves collecting immature blood cells, called blood stem cells, from patients who have been treated with growth factors during recovery from chemotherapy and reinfusing these cells into the patient. This appears to produce even speedier recovery than using bone marrow alone.