The invention relates to the field of medical devices and methods used in the treatment of diseases such as cancer which have the ability to metastasize within a patient's body. More specifically, the invention is directed to methods and devices for accessing sentinel lymph nodes associated with a lesion site within a patient's body and anchoring devices to these nodes accessed so that they may thereafter be selectively removed and analyzed to determine whether disease has spread from the primary lesion site to the sentinel lymph nodes. In the case of breast cancer patients, such methods and devices may eliminate the need for complete axillary lymph node dissection in patients who do not require such invasive and debilitating procedures.
Metastasis, or migration of cancerous cells, typically occurs through lymph ducts. Sentinel lymph nodes are so-called because, where metastasis occurs, such lymph nodes are often the first locations to harbor metastatic cancer cells. These lymph nodes thus serve as sentinels warning of the spread of the cancerous lesion. A sentinel lymph node may be identified by injection of radioactive material into a primary lesion site such as a cancerous tumor. Detection of radiation at a location other than the injection site indicates that migration of the radioactive material has occurred. The first lymph nodes into which the radioactive material migrates are thus identified as the sentinel lymph nodes.
With regard to breast cancer patients specifically, the determination of the severity of the disease or staging is frequently determined by the level of lymph node involvement in those lymph nodes which correspond to the primary cancer lesion site in the breast. The lymph nodes which correspond to the breast area are typically located in the armpit or axilla of the patient and are connected to the breast tissue of the patient by a series of lymph ducts. Other likely areas for sentinel nodes include inframammary and submammary locations and elsewhere in the patient's chest. The sentinel lymph nodes can be in fluid communication with other surrounding lymph nodes, however, lymph drainage from the lesion site will first flow to the sentinel lymph nodes. Thereafter, lymph fluid drainage may then continue on to lymph nodes surrounding the sentinel nodes.
Studies have shown that by the time a typical breast cancer lesion reaches the size of 1-2 cm, the cancer will have metastasized to at least one of the sentinel lymph nodes in about one third of patients. Malignant cells break off and drain through the lymph fluid ducts to the lymph nodes and will be apparent in excised lymph nodes if the malignant cells embed in the lymph node. In patients with more advanced disease, the likelihood of spread to sentinel nodes is higher as is the likelihood of spread of the disease to the lymph nodes surrounding the sentinel lymph nodes.
As discussed above, when a tumor lesion is under 1-2 cm, only about ⅓ of patients will have cancer cells in the corresponding lymph nodes, and in the patients where the disease has spread to the lymph nodes, it is often confined to the sentinel lymph nodes.
In the past, a breast cancer patient would normally have a complete axillary lymph node dissection as an adjunct to removal of the primary lesion in the breast. Thus, the patient's entire lymph node system in the armpit area is removed and biopsied to determine the stage of the cancer and what further treatment was required. However, as discussed above, when the lesion is under 1-2 cm, two thirds of the patients had no migration of cancer cells to the lymph nodes at all, and in others, cancer had only migrated to the sentinel lymph nodes. Thus, total axillary lymph node dissection in two-thirds of the cases were unnecessary. It should be noted that total axillary lymph node dissection can be an extremely painful and debilitating procedure for patients who often suffer from severe lymph edema as a result of the body's inability to channel the flow of lymph fluid once most or all of the lymph nodes have been excised.
Wires and other devices have been used to anchor devices and to mark suspected cancerous lesion sites within a breast. Such wires may have exposed, sharp ends to cut into tissue, and may expose physicians to accidental injury during excision of tissue. Placement of such marking and anchoring devices is typically performed in the operating room. However, there is a need for methods and devices that can be used to determine the location of sentinel lymph nodes corresponding to a patient's primary lesion site, in addition to the primary lesion site itself, and a reliable means of accessing the sentinel lymph nodes to determine whether they are involved in the disease. If the sentinel lymph nodes are determined not to have cancer cells within them, then a total axillary lymph node dissection may be avoided. Anchoring devices near to such sentinel nodes would be useful if the sentinel lymph nodes are determined to be involved in the disease.
Radioactive materials have been used as localizing agents which can be injected into the area of a primary lesion to monitor the flow of the materials within the patients body using a variety of detectors. A pharmaceutically-acceptable solution containing a radioactive material may be termed a radiopharmaceutical. Suitable radioactive materials include the radioactive elements Technetium 99, Indium 111, Iodine 123 or Iodine 125.
Although techniques exist to locate the sentinel lymph nodes of a patient with such radiopharmaceutical tagging, what has been needed are methods and devices to precisely access the sentinel lymph nodes of the patient and to anchor a device adjacent sentinel lymph nodes should it be determined that axillary node dissection is necessary.