About Sentinel Lymph Node Mapping
What is Sentinel Lymph Node (SLN) Mapping?
Sentinel Lymph Node Mapping or SLN is a surgical technique. It is used to identify the first 1 to 3 lymph nodes in the axillary (arm pit) area which may have the first site of breast cancer spread. The SLN is seen by using both a radioactive substance and a special blue dye.
Why is SLN mapping important?
Your doctor can use this information to help you choose the best therapy after surgery is done. The use of chemotherapy and radiation therapy to treat breast cancer is determined by the presence of breast cancer cells that have spread (metastasized) to the axillary lymph nodes. The presence or absence of cancer cells in the axillary nodes is the most important predictor of overall risk for the recurrence of breast cancer. And only 1/3 of patients will have positive axillary nodes present at their initial surgery.
Surgeons have traditionally performed a much more extensive axillary lymph node dissection to check for cancer spread. An axillary lymph node dissection involves the removal of a packet of tissue containing between 5 and 20 lymph nodes. This operation may have many minor effects. The most major adverse effect is lymphedema of the arm. This only occurs in a small number of patients, but can cause significant problems in activities of daily living.
The axillary node dissection is an important way to check how many of the lymph nodes are involved. It also helps to decrease the risks of recurrence of cancer in the axillary area. With the new SLN mapping surgery, a smaller operation gives your doctor the same information about the number of nodes that have cancer in them while leaving the other nodes alone. This helps to decrease side effects after the surgery.
Surgeon training in this procedure is very important to its success. Experience shows that not all surgeons can be equally successful in finding SLN’s. Also not all hospitals have equal success in finding SLN’s. As a result of being done on a standardized protocol each patient can be assured that the technique of SLN is being performed consistently and safely.
The surgeons a the Center for Breast Health (CBH) are required to perform a minimum of ten SLN mappings with a backup axillary node dissection as part of their training in this technique. This is to assure us the surgeon is finding the true SLN and making sure there are no false negatives. Once past this stage a surgeon has the option of omitting the axillary lymph node dissection.
What is the importance of False Negatives?
A SLN is considered being a "false negative" if it does not have cancer cells, but there are other axillary lymph nodes that have cancer. In medical literature reported on a national basis the false negative rate is about 5%. Surgeons at the Center for Breast Health performing this surgery have noted a false negative rate of about 1%. Another statistical measurement of the success of this surgical technique is the "find rate". This is a measurement of the success of actually finding or locating the SLN. It is not 100% possible to do so with our current technology. At the Center for Breast Health, ours is about 80%. Although this is a bit less than what is reported nationally, it is our opinion that a lower "find rate" is better than having a higher "false negative" rate. During the surgical procedure if an SLN cannot be detected, the patient has a traditional axillary node dissection, so that all of the axillary nodes are checked. Once a SLN is located, if the pathologist determines that it is "negative" for cancer, further lymph node dissections are not done.
Which Breast Cancer Patients are suitable for SLN mapping?
A patient with a smaller cancer (usually less than 3 cm in size) that has a low chance of having lymph node involvement. Patients over the age of 80 or patients with previous breast cancer or axillary surgery are not eligible for SLN mapping. Also, some women with breast implants may not be suitable for SLN mapping because of the implant location or incision placement. In general if a patient has a significant risk for axillary nodal spread of their breast cancer a SLN mapping is not indicated.
How do I find out more information about SLN at the Center for Breast Health?
Call us 563-421-7625, or send an email. The general surgeons at the Center for Breast Health are available for consultation and additional opinions without specific physician referral. It has been our experience that by seeing a surgeon at CBH a patient's questions can be answered and they leave with a better understanding of their treatment options for breast cancer.