Breast cancer cells gets their start in the breast, but at some point, these cells acquire the ability to travel to other parts of the body, a process known as “metastasizing.” As a general rule, the larger the cancer, the more likely it has acquired the ability to metastasize.
An important route that cancer cells take to leave the breast are through the lymphatic channels to lymph nodes, primarily under the arm. These lymph nodes are checked using the sentinel node procedure, and if disease is found, it is likely that cancer is present in other parts of the body as well. In this situation, chemotherapy is usually recommended in order to destroy those metastasizing cancer cells.
Sometimes, the cancer can leave the breast directly through the blood vessels, bypassing the nodal system. In this setting, the sentinel node will be negative but there may be circulating cancer cells that need chemotherapy to be controlled. To sort this situation out, your doctor may order an OncoType DX Recurrence Score on your cancer. This test is performed on the tumor itself and it determines what genes are turned on in your specific cancer. Based on the pattern of genes found in your cancer, we can predict whether or not chemotherapy will be of benefit. A low OncoType DX Recurrence Score is associated with a cancer that is generally very responsive to hormone blocking strategies and do not respond much to chemotherapy. In this setting, a hormonal blocking agent is prescribed instead of chemotherapy. If the OncoType DX Recurrence Score is high, the tumor will benefit from chemotherapy in addition to a hormonal blocking agent.
While chemotherapy is usually delivered after the tumor is removed from the breast and the status of the lymph nodes is known, in some cases, there are benefits to delivering the chemotherapy before the operation. This kind of treatment is known as “neoadjuvant chemotherapy.” By giving the chemotherapy before the tumor is removed, the oncologist has the opportunity to see firsthand how responsive that particular tumor is to the selected chemotherapeutic regimen. About 20% of the time, the tumor will shrink completely with chemotherapy alone. While the part of the breast that the tumor developed in must still be removed surgically in order to avoid recurrence of the disease, those women who have such a good response have a better prognosis than would have been predicted otherwise. For those women who do not have a complete response to chemotherapy, a different drug may be offered to improve her response. An added benefit of neoadjuvant chemotherapy is that, in many cases, a woman who would have required a mastectomy due to the large size of her tumor, becomes a candidate for breast preservation after the tumor shrinks.
The prospect of chemotherapy can be the most frightening part of breast cancer treatment for many women. While these drugs are very powerful and do have side effects, oncologists have become very good managing them. Many of these women describe their chemotherapy experience as “not as bad as I had expected” once they have completed their treatment.