Patients with advanced breast cancer who have more than five circulating tumor cells in the blood may have a more dangerous form of the disease, according to a study published in the Aug. 19 issue of The New England Journal of Medicine.
The pivotal study could lead to more tailored treatments that would spare some women from the most potent chemotherapy, or, conversely, recognize which patients need more aggressive therapy at the start of treatment, says the study's lead author Massimo Cristofanilli, M.D., associate professor in The University of Texas M. D. Anderson Cancer Center's Department of Breast Medical Oncology.
"This is the first time that we can actually stratify metastatic breast cancer patients based on their risk," says Cristofanilli. "When a physician assesses a woman with metastatic breast cancer, it is very difficult to make an accurate prediction of her prognosis. Now we may know more about what the prognosis will be, based on a simple blood test and a new technology. One day we may be able to suggest to a patient - based on personal risk - a more aggressive treatment, a less aggressive treatment, or no treatment at all."
Metastasis is the most life-threatening aspect of cancer, says Cristofanilli. To metastasize, cancer cells must leave the site of the primary tumor, travel through the blood and proliferate in a new site. Until recently, doctors have not been able to reliably isolate circulating tumor cells in the blood. Within the last few years, several methods have been developed to label tumor cells with antibodies that can then be measured precisely, identifying even one tumor cell in a vial of blood, writes Science Daily.
According to Boston Globe, more than 1.2 million people are expected to be diagnosed with breast cancer this year worldwide, and the disease is expected to kill 40,000 in the United States.
Cells of a tumor sometimes break off and circulate in the blood. When those nomadic cells find a new home and start to grow, a process known as metastasis, cancers become much harder to treat.
The technique to count such cells, known as the CellSearch System, was developed by Veridex LLC, a Johnson & Johnson company, in conjunction with Immunicon Corp., which funded the study. Each test is expected to cost $300 to $400.
Doctors now use a variety of methods to try to predict which treatment will be most effective. They include tumor size and type, the patient's age, whether cancer cells have spread to adjacent lymph nodes, and the tumor's sensitivity to estrogen.
The Cristofanilli team found that women with high levels of cancer cells in their blood survived for 10.1 months on average, while those with low levels survived for more than 18 months.