Sentinel node biopsy

A Sentinel node biopsy (SLNB) is done to identify, remove, and examine the sentinel lymph nodes. Sentinel lymph nodes are the elementary lymph nodes to which the cancer has spread from the primary organ. SLNB helps to know the spread of the cancer by breaking from the primary tissue. One or more SLN are removed and observed under the microscope to identify the spread. A positive report indicates the spread and a negative report indicates that the cancer has not spread. 

Sentinal Lymph Nodes:

Lymph nodes are part of the lymphatic system which is a part of the body’s immune mechanism. It carries the waste products from the body and also secretes fluid for the infection-fighting white blood cells of the body. They filter microorganisms like bacteria, viruses, and other microorganisms. Many lymph nodes are present in the neck, chest, underarms, abdomen, and groin. As these lymph nodes are spread across the body, cancer cells when they are spreading first reach the lymph nodes. The first lymph nodes to which the cancer cells spread are called the sentinel lymph nodes. Lymph nodes biopsied and examined under the microscope show the presence of cancer cells when they have cancer in their body. 

Indications:

SLNB is indicated to see the spread of the cancer. This is indicated in cancers of the breast, endometrium, penile, and melanoma. It is also prescribed for other cancers like 

• Cancer of the cervix and vulva 
• Cancer of the colon and esophagus 
• Head and neck cancers 
• Non-small cell lung cancer 
• Gastric and thyroid cancer 

Advantages:

SLNB has many advantages. 

• It helps to know the spread of the cancer 
• It helps decide the staging of the cancer 
• It helps in the treatment plan 
• It helps in avoiding extensive surgeries if the biopsy results are negative 
• It also prevents the recurrence of the tumors by removing the sentinel lymph nodes 

Before the procedure:

Before the SLNB, it is important to understand the necessity of the procedure by discussing it with the healthcare provider (HCP). Complete details regarding the medical, surgical, allergic, and medication history should be given to the HCP. A list of medications to be stopped and another list of medicines to be used before the procedure will be given. One has to undergo a few blood tests to understand the current medical condition. Advanced imaging studies like MRI or CT will also be taken to assess the extent of the tumor. 

A SLNB will be done on an empty stomach under anesthesia. Hence it is necessary to refrain from eating anything 8-12 hours before the procedure. Inform the healthcare provider of any previous allergies to anesthesia. In case of pregnancy, inform the healthcare provider as imaging studies cannot be done in pregnancy. A radioactive dye is injected near primary cancer. If the cancer is draining to a particular lymph node, then the dye is taken up by the sentinel lymph node. In some cases, a blu dye may be injected, coloring the sentinel lymph node in blue. This is the first step in SLNB which is done many hours or a day before the procedure. 

During the procedure:

The SLNB is done under anesthesia. Small cuts are made on the lymph node area. If a radioactive solution is injected, the HCP uses a gamma detector camera to identify the lymph node. The sentinel lymph node with the radioactive solution emits radioactivity which can be easily visualized with the gamma detector. If a blue dye is used, the sentinel node takes up the maximum dye that can be easily identified. The identified sentinel nodes are removed. This SLNB can be done alone or along with a cancer removal procedure. The removed sentinel nodes are sent to a laboratory for visualization under the microscope. The number of lymph nodes to be removed depends on the discretion of the HCP. 

After the procedure:

The individual is taken to a recovery room and monitored till the vitals are stabilized. The entire procedure takes about 20-30 minutes. There will be mild soreness due to the procedure. Antibiotics and painkillers will be given to subside the pain. After the procedure, one should refrain from lifting heavy weights. 

Interpretation: 

Further procedures depend on the SLNB report. If the SLNB report gives negative results, it means the cancer has not spread, so there is no need for any further procedures, However, if the SLNB report shows the presence of cancer cells then more lymph nodes have to be removed. 

In breast cancer, if the sentinel lymph nodes are found in the axillary lymph nodes, SLNB helps in the treatment of breast cancer by removing the tumor progression. Individuals with melanoma who have undergone sentinel lymph node biopsy and got negative results have been spared extensive lymph node surgeries. 

Side effects:

Side effects associated with the procedure include bleeding, pain and bruising, infection, allergy to the dyes used, scarring, stiffness of the arm, and bluish or greenish discoloration of the urine. 

Risks and complications:

SLNB is associated with fluid buildup in the area of the lymph nodes that were removed. This causes pain and swelling due to fluid accumulation. This occurs due to the removal of multiple lymph nodes. Multiple cord-like structures are developed under the arm when lymph nodes are removed from the axillary area. This cording is called axillary web syndrome. This forms many months after the lymph nodes are removed. 

Conclusion:

A sentinel node biopsy surgical procedure is done in cancer patients to check the spread of the cancer to the lymph nodes. Based on the involvement one or more nodes are removed and sent for pathological examination. SLNB detects the early spread or recurrence aiding in early treatment.