Stage IV breast cancer has traditionally been considered an incurable cancer. In the mid to late 1980's the average patient with stage IV breast cancer treated with low-dose chemotherapy survived 8-10 months before their cancer relapsed and less than 5% of patients could expect to survive 5 years without their cancer recurring. In 1988, the results of a small clinical trial treating 22 women with stage IV breast cancer treated with high-dose chemotherapy and autologous stem cell transplant were published. Fourteen percent of these patients treated with high-dose chemotherapy survived without their cancer recurring beyond 5 years.
By 1997, these patients had been observed over 10 years and the original 14% remain alive without a relapse of their cancer and appear cured of their disease. It is important to understand that because over 50% of patients with stage IV breast cancer relapse, it is not useful to compare the response rate to chemotherapy, the average duration of survival or time to relapse. When evaluating treatment strategies in stage IV breast cancer, patients should compare the percent of patients alive with or without relapse 3-5 years from treatment to determine whether a treatment is truly superior.
In one clinical trial published in 1997, women in complete remission after induction chemotherapy were treated with high-dose chemotherapy or no further treatment. At 5 years from diagnosis, 24% of the women treated with immediate high-dose chemotherapy survived without disease recurrence, compared to only 8% of the women who did not receive further treatment.
This study suggested that there were no differences in survival between the standard-dose and high-dose chemotherapy regimens in women with metastatic breast cancer who had a complete or partial response to initial standard-dose therapy. However, the number of women treated in this trial does not allow the identification of any subsets of women that might benefit more than the overall group from the high-dose regimen.
Early detection is clearly the most important factor in breast cancer survival rates. Breast cancer detected at Stage 1 while it is still localized to the breast has a survival rate of 98%-100%, while metastasized breast cancer first detected at Stage 4 drops down to 16%-20%.
The main reason patients with breast cancer fail treatment is relapse. Relapse of breast cancer occurs because the high-dose chemotherapy is either unable to kill all the cancer cells in the patient and/or because cancer cells "contaminating" the stem cells are infused back into the patient. The majority of relapses occur because all the cancer cells were not destroyed by the high-dose chemotherapy treatment. However, some relapses may be due to infusion of breast cancer contaminated stem cells. Doctors are performing clinical trials designed to improve the treatment of breast cancer with high-dose chemotherapy that include the following approaches alone or in combination:
North American white women have the highest rates of breast cancer in the world, but the 5-year survival rate for all stages (Stage 1, Stage 2, Stage 3, and Stage 4) combined is 88% for the U.S. A recent study found European countries have lower 5-year breast cancer survival rates, with England at 77.8% and Ireland at 76.2% (Lancet Oncology).