Presence of Cancer Cells in Circulating Blood Predicts Worse Outcomes
According to an article recently published in the Journal of Clinical Oncology, the presence of small amounts of cancer cells in circulating blood as detected by a gene panel predicts a 300% increased risk of death among women with early breast cancer who undergo high-dose therapy and a stem cell transplant.
Stages II–III breast cancer refer to cancer that has spread from the breast but not to distant sites in the body. Patients with Stages II–III breast cancer typically undergo surgery, chemotherapy, and radiation therapy.
Adjuvant therapy is additional treatment administered after initial surgery and radiation therapy. The goal of adjuvant therapy is to eliminate any cancer that remains after surgery or radiation therapy; this is intended to reduce the risk of cancer recurrence.
Despite undergoing surgery and radiation, some breast cancer patients already have small amounts of cancer that have spread outside the breast. These cancer cells are referred to as micrometastases and cannot be detected with currently available tests.
The presence of micrometastases causes breast cancer recurrences after local treatment with surgery and/or radiation therapy. To reduce the risk of a cancer recurrence, breast cancer patients may receive adjuvant therapy with chemotherapy, hormonal therapy, or biologic therapy. Unfortunately, a significant portion of women who are treated with standard adjuvant therapy experience a recurrence, particularly those with a greater extent of cancer spread or more aggressive cancers.
In an effort to reduce the chance of recurrence, researchers have been evaluating the use of high-dose chemotherapy and stem cell transplantation in women with breast cancer.
High-dose chemotherapy generally kills more cancer cells than moderate doses, but this approach also results in more side effects. One particular side effect is damage to the blood-producing hematopoietic stem cells; these immature blood cells are produced in the bone marrow and mature into red blood cells (which carry oxygen to tissues), white blood cells (which fight infection), and platelets (which aid in blood clotting).
To restore stem cells that are depleted by high-dose chemotherapy, patients may undergo an autologous stem cell transplant. An autologous stem cell transplant involves collection of the patient’s own stem cells prior to chemotherapy; these cells are then reinfused after chemotherapy.
Previous studies have produced conflicting results regarding outcomes in women with early-stage breast cancer who are treated with high-dose chemotherapy and stem cell transplant. As a result, physicians generally do not accept this procedure other than in a clinical trial. However, it appears that specific sub-groups of these patients may achieve significant benefit from high-dose chemotherapy, and researchers continue to evaluate data to specifically determine which women will benefit.
Researchers from Spain and Johns Hopkins University recently conducted a study to evaluate the significance of cancer cells detected in circulating (peripheral) blood (PB) among women with early breast cancer considered to be at a high risk of developing a recurrence.
This study included 84 women whose cancer had spread to more than 10 lymph nodes under the arms. They were all treated with adjuvant chemotherapy and radiation or hormone therapy if appropriate. The women then underwent high-dose chemotherapy and a stem cell transplant. A gene panel utilizing a sensitive laboratory test called real-time polymerase chain reaction (RT-PCR) was used to identify circulating PB cells. Patients were followed for over five years.
- Among patients with detected PB cancer cells, the rate of cancer relapses was increased by 269% compared to those without PB cancer cells.
- Among patients with detected PB cancer cells, the risk of death was increased by 300% compared to those without PB cancer cells.
- Cancer relapses occurred at 84.2 months for those without PB cancer cells, compared with only 31.3 months for those with PB cancer cells.
The researchers concluded that using a gene panel with results detected by RT-PCR identifies patients with breast cancer who achieve a significantly greater benefit from high-dose therapy and a stem cell transplant. Results such as these contribute to evidence that specific subgroups of patients with breast cancer may derive great benefit from high-dose chemotherapy and stem cell transplantation. Patients diagnosed with early breast cancer may wish to speak with their physician regarding their individual risks and benefits of participating in a clinical trial further evaluating high-dose therapy and stem cell transplantation. Two sources of ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and www.cancerconsultants.com.
Reference: Quintela-Fandino M, Lopez J, Hitt R, et al. Breast Cancer–Specific mRNA Transcripts Presence in Peripheral Blood After Adjuvant Chemotherapy Predicts Poor Survival Among High-Risk Breast Cancer Patients Treated With High-Dose Chemotherapy With Peripheral Blood Stem Cell Support. Journal of Clinical Oncology. 2006;24: 3611-3618.
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