Overview of Axillary Sentinel Lymph Node Biopsy
If you’re diagnosed with breast cancer, doctors use a process known as staging to determine how much the cancer has spread. One vital area they examine are the regional lymph nodes, which are small glands that produce and store cells that fight infection and disease.
A method called the sentinel lymph node biopsy helps doctors assess the condition of the axillary lymph nodes positioned in your armpit, without having to perform a full axillary dissection, or removal of all nodes from that area. The sentinel nodes are the first lymph nodes that the cancer is likely to spread to from the breast. By identifying and removing these nodes, doctors can figure out the extent of the cancer spread.
Usually, discovering cancer in a sentinel node led doctors to perform a complete axillary dissection. However, recent studies suggest that this full procedure might not be necessary for all cases, even when the sentinel node tests positive for cancer. This is good news because the broader operation can lead to complications such as lymphedema (swelling caused by a blockage in the lymphatic system), nerve injury, lasting pain, and lymphangiosarcoma, a rare form of soft tissue cancer.
Doctors are cautious in deciding who can safely skip the complete axillary dissection when the sentinel node is positive with cancer. A patient generally should have a small tumor (classified as T1 or T2) and have less than three nodes affected by the tumor.
Anatomy and Physiology of Axillary Sentinel Lymph Node Biopsy
The axillary sentinel lymph node, which is typically found in the armpit’s fat pad, is categorized as a level I or level II lymph node. These nodes are known to doctors as the pectoral (near the chest) and clavicular (near the collarbone) nodes. The fat pad in the armpit region is deeper compared to the normal fatty layer just beneath the skin and has a different feel.
When the surgeon is doing a biopsy to check these lymph nodes, they would make an incision in this deeper layer of skin-fascia. Below this fascial layer, you’ll find another structure called the clavipectoral fascia. This fascia is located beneath a muscle in your chest, the pectoralis major, and includes various important structures such as blood vessels (axillary artery and vein) and nerves (axillary nerve).
During the surgery, the surgeon might come across two main arteries branching off from the axillary artery. These are the lateral thoracic artery and thoracodorsal artery. There are also two main motor nerves in this area that control the movement of muscles. These are the long thoracic and thoracodorsal nerves.
If injured, the long thoracic nerve could lead to a condition where the shoulder blade sticks out, often called ‘winging of the scapula’. There are also several small nerves which can be found in the fat pad of the armpit, like the intercostobrachial nerve. Damage to these nerves can result in a numb feeling in the upper inner part of the arm.
The surgeon should not come across the network of nerves in the upper chest and shoulders (brachial plexus) during the procedure. This is possible if the dissection doesn’t go above the axillary vein. Going above this vein does not help in counting the lymph nodes but can result in serious conditions like lymphedema (swelling due to problems in lymph drainage) and nerve damage.
Why do People Need Axillary Sentinel Lymph Node Biopsy
A sentinel lymph node biopsy is a test to see if breast cancer has spread to the lymph nodes. This test is usually done for early-stage breast cancers of the ductal and lobular types. These types of cancer often spread to the lymph nodes. However, there are certain kinds of breast cancers, like cystosarcoma phyllodes tumors, that generally spread to the lung instead of the lymph nodes. So, they don’t need this test.
If someone is diagnosed with invasive ductal and lobular cancers, and the cancer is still small (known as T1 and T2), they usually have this test. But if images taken by ultrasound, x-ray, or MRI show that the lymph nodes might be bigger, a different kind of biopsy is done first. This biopsy takes a small piece of the enlarged lymph node through a procedure called a ‘core needle biopsy’.
It’s debated whether to fully remove all the lymph nodes in the armpit if two or more have cancer cells. There’s also controversy over whether to use imaging tests on patients who don’t have enlarged lymph nodes. Some studies say it’s not helpful, while others say that imaging is useful for identifying patients with a large number of affected lymph nodes. The decision usually depends on the situation.
In some cases, a complete lymph node removal might be considered if a PET scan shows cancer in the lymph nodes. However, if the PET scan doesn’t show cancer, the next step would typically be a sentinel lymph node biopsy.
A unique situation arises for patients who receive chemotherapy before surgery. In such cases, the lymph node test is usually performed before the chemotherapy since the result might not be reliable after chemotherapy.
Whether or not to perform a sentinel node biopsy when doing a preventive mastectomy (removal of a healthy breast to reduce the risk of cancer) is another area of debate. This is because a small amount of hidden cancer is found in 7% to 10% of these preventive surgeries. Both MRI and sentinel lymph node biopsy have been studied in these cases. MRI is less accurate and more expensive than sentinel lymph node biopsy. Therefore, many healthcare providers might recommend a sentinel lymph node biopsy for high-risk patients undergoing preventive mastectomy.
Finally, for breast cancer that is present in more than one part of the breast, sentinel lymph node biopsy has proven effective in patients whose lymph nodes are not enlarged. With a very low risk of the cancer coming back in the lymph nodes, some doctors might recommend removing all the lymph nodes in the armpit if the sentinel lymph node biopsy is positive.
When a Person Should Avoid Axillary Sentinel Lymph Node Biopsy
Sentinel node biopsy is a procedure where a doctor checks for cancer in the first few lymph nodes (small glands that filter harmful substances from the body) near a tumor. However, it might not be the best course of action for patients with large breast tumors or many lumps in the armpit (axillary) area, as these conditions suggest widespread disease in this region. In such cases, other options might be considered.
For instance, there’s research showing that a preoperative lymph node core needle biopsy could be useful. In this procedure, a doctor uses a needle to extract a sample of tissue from a lymph node for examination before surgery. If this test shows cancer, it’s more likely that the patient will need a complete axillary dissection, where all the lymph nodes in the armpit area are removed due to the increased number of affected nodes.
However, there’s debate about the role of the sentinel lymph node biopsy in patients receiving neoadjuvant chemotherapy, a treatment given before the main treatment to shrink a tumor. Most patients have their lymph nodes tested prior to this therapy. This is because performing a sentinel node biopsy after neoadjuvant chemotherapy can often yield incorrect negative results (indicating cancer is not present when it actually is) more than 10% of the time.
Equipment used for Axillary Sentinel Lymph Node Biopsy
To carry out this procedure, we need a special room with specific surgical tools, a team of medical professionals to assist, and appropriate anesthesia. We also need a tool called a gamma probe, which is used to find the axillary sentinel lymph node during the biopsy using a radioactive marker. Keep in mind that there are several kinds of gamma probes out there. The commonly used ones can count and also measure an average of the radioactive readings. Since the node becomes radioactive, its management regarding the leftover radiation in the room after the procedure is done according to hospital rules.
Who is needed to perform Axillary Sentinel Lymph Node Biopsy?
Different types of surgeons – general surgeons, cancer surgeons, and breast surgeons – have the skills necessary to perform a special test called a sentinel lymph node biopsy for patients with breast cancer. This test is typically done while the patient is under general anesthesia, which means the patient is fully asleep and will not feel any pain, or deep sedation, which is a state where the patient is relaxed and sleepy but not totally unconscious.
If a special type of imaging liquid called a radiotracer is used, it’ll typically be injected by a radiologist, which is a doctor who specializes in medical imaging. They’ll put this liquid either into or close to the cancerous lump or into the tissue beneath the nipple, before the biopsy test starts.
Preparing for Axillary Sentinel Lymph Node Biopsy
Before your doctor can perform a particular procedure called a ‘completion axillary dissection’, which typically involves removing lymph nodes from the armpit, they need to have an open and clear conversation with you. This talk is needed so you would understand why the procedure is necessary and provide your consent. It’s crucial to note that this procedure isn’t usually done together with a ‘sentinel node biopsy’, which is a test to find out if breast cancer has spread. But, in some cases, if results from a sample of tissue (‘frozen section’) are available during the operation, your doctor might decide to perform the axillary dissection.
On the day of the operation, if a radiotracer (a radioactive substance) is used, you would need to visit the radiology department early for an injection. There’s also an optional procedure called ‘lymphoscintigraphy’ that could be beneficial. This procedure helps the doctor locate the sentinel node or the first lymph node where cancer might spread. It’s especially useful if there is a chance the node might be located in an unusual place, like the ‘internal mammary nodes’, which are lymph nodes located near your breast bone. However, these nodes are not usually removed. Notably, cancer spreading to these nodes could be more common if you have a tumor on the lower inner part of your breast.
How is Axillary Sentinel Lymph Node Biopsy performed
In simpler terms, the procedure begins by preparing the patient’s skin for surgery. The process of finding and removing the lymph nodes in the armpit (axillary node biopsy) is done before any other breast surgery that might be needed. If a blue dye and a special material called a radiotracer are going to be used, the blue dye is injected either near the tumor or under the nipple area. This is done right before the operation starts because the blue dye moves faster in the lymph system, which is the body’s disease-fighting network, than the radiotracer. Massaging the breast can help the blue dye move properly.
If a radiotracer has been injected earlier, a tool called a gamma probe can be used to help choose the location for the surgeon to cut, which is usually on the side of the large chest muscle (pectoralis major). This tool then helps the surgeon find the lymph node that it detects inside the fat layers under the skin of the armpit. If blue dye is also being used, this lymph node often appears blue as well. It’s important for the surgeon to avoid pointing the gamma probe towards where the dye and tracer were injected into the breast, as this could wrongly show up as an increased level of radioactivity, which can lead to wrong directions during the surgery. Upon finding the lymph nodes, they are removed. Readings are then taken from the removed lymph nodes and from the surgical site to check if more lymph nodes need to be removed. Once this is completed, bleeding is stopped (hemostasis), and the area where the cut was made is closed according to what the surgeon thinks is best. There’s no need to immediately examine the lymph node during the surgery (frozen section) if no further removal of nodes in the armpit area (completion axillary dissection) will be done based on the results.
If only the blue dye is being used, the cut is made along the side edge of the large chest muscle. The lymph node that shows up blue can usually be seen directly and removed.
Possible Complications of Axillary Sentinel Lymph Node Biopsy
A sentinel lymph node biopsy is a type of surgery that is considered less severe than a full axillary dissection, which involves removing lymph nodes from the armpit area. Like all surgeries, it comes with some risks. These include bleeding, infection, nerve damage, lymphedema (swelling caused by a blockage in the lymphatic system), and the possibility of needing more surgery if there’s a lot of disease in your lymph nodes or if the disease comes back in the armpit area. But overall, this procedure is considered to have low risks.
What Else Should I Know About Axillary Sentinel Lymph Node Biopsy?
The treatment for breast cancer has been greatly improved by the use of a procedure called sentinel node biopsy. This technique has been extremely beneficial, helping many women avoid the complications linked to the more invasive procedure known as axillary dissection.
In 2010, the ACOSOG conducted an important study that showed patients with early-stage breast cancer, specifically those having only small-sized breast tumors, got just as much benefit from a sentinel node biopsy as they did from axillary dissection. All patients in the study also received follow-up chemotherapy treatment.
While the study was not without its flaws, its results have been widely accepted and embraced within the medical community. Therefore, axillary dissection is not the favored choice in many cases when the sentinel node is confirmed to contain cancer cells.
Additionally, further studies have shown that whether patients receive a sentinel lymph node biopsy or axillary lymph node dissection doesn’t influence their chances of survival ten years after treatment. This is more evidence showing the benefits of sentinel lymph node biopsy in breast cancer treatment.