Overall, melanoma, a type of skin cancer, is an increasing global healthcare problem. In the United States, the Surveillance, Epidemiology and End Results (SEER) of National Cancer Institute reported 91,270 new cases in 2018, representing an incidence of 22 new cases per 100,000 individuals.
In Australia, melanoma of the skin incidence rates have increased from 53 cases per 100,000 people in 2000 to an estimated 70 cases per 100,000 people in 2024. In 2024, it is estimated that 35% of melanoma of the skin cancer cases are diagnosed on the trunk of the body, 26% on the upper limbs (including shoulder), 18% on the lower limbs (including hip) and 7.7% on the scalp and neck.
The proportion of melanoma of the skin diagnosed by site varies by sex. For example, in 2024 it is estimated that 25% of melanoma of the skin cases are diagnosed on the lower limbs (including hip) for females while for males it is 13%. Conversely, the trunk accounts for 41% of the cases for males and 27% for females.
Melanoma of the skin incidence rates for females are estimated to be 56 cases per 100,000 females in 2024 while male rates are 86 cases per 100,000 males.
Although melanoma is responsible for only about 5% of cancer cases, the prognosis is very bad when the disease has gone beyond the skin (lymph nodes and distant organs), even with substantial improvement in survival rates. Sentinel lymph nodes are the first lymph nodes to which cancer cells may spread from a primary tumor site, playing a crucial role in filtering lymph fluid and fighting infections.
A sentinel node biopsy is performed by identifying and mapping the sentinel lymph node using lymphoscintigraphy with a radioactive tracer and a blue dye injection, which guide the surgeon to the correct node for removal.
The other parts of the lymph node biopsy (sentinel and full clearance) are frequently used in many other cancers, such as breast cancer, to understand how far a cancer might have spread.
Why is Melanoma So Dangerous?
Gene mutations in many Melanoma is one reason why melanoma is so aggressive is that it quickly wracks up mutations compared to few other cancer types. Genetic research from the past decade has broken down melanoma into four primary genetic subclasses: BRAF mutations, RAS mutations, NF1 mutations and triple wildtype (WT). Although these mutations are the primary genetic drivers of cutaneous melanomas, acral and mucosal melanomas frequently feature an alternative molecular profile marked by less frequent mutations with different identities.
If melanoma is detected early, it can usually be successfully treated with surgery. If the disease spreads, then it can be harder to treat and less chance of a good outcome. The sentinel lymph node biopsy (SLNB) is crucial to learn when melanoma reaches the lymphatic system.
What is Sentinel Lymph Node Biopsy (SLNB)?
Sentinel lymph node biopsy (SLNB) is a surgical technique to determine if melanoma has spread to the lymph nodes. The sentinel lymph node is the first lymph node that cancer cells in a primary tumor usually spread to. Sentinel lymph node biopsy removes fewer lymph nodes compared to more extensive procedures, leading to benefits such as reduced risk of complications like lymphoedema, pain, and numbness, along with a shorter hospital stay and quicker recovery time. Doctors can identify and analyze this node to find the existence of cancerous cells before they metastasize, which is very helpful in deciding the treatment.
A small amount of radioactive substance or blue dye is injected near the tumor during the procedure. The tracer is carried to the sentinel lymph node–the first node under the skin, located at your wrist or near where cancer centers–to locate early signs that cancer was spread. If the sentinel node is positive (it contains melanoma cells), it means that the cancer has started to spread and more extensive treatment is needed. If it shows nothing, there is usually no need for more lymph node surgery.
How many nodes are taken in a sentinel node biopsy?
For a sentinel lymph node biopsy (SLNB) usually only one to three lymph nodes are removed. The sentinel lymph node (or nodes) is the one to which cancer cells are most likely to have metastasized from a primary tumor.
The total number of nodes removed during the procedure is determined by the number that are identified as sentinel events draining from the primary tumor site. The radioactive tracer and another agent, either a blue dye or an additional type of radioactive tracer with a telltale pharmacokinetics profile, permit proper nodal identification.
If more than one sentinel node is found, all of the identified nodes are removed and evaluated for cancer cells to help stage the cancer correctly and make an optimal treatment plan. But, in general only few nodes needs to be considered. This technique involves removing fewer lymph nodes than those resected from more extensive lymph node dissection, thus reducing the risk of complications such as lymphedema.
What are the possible side effects of sentinel node biopsy?
SLNB is an essentially risk-free operation, but as with any surgery, it has some risks and side-effects to consider. Side effects from SLNBThese are the most common side effects of SLNB
Cancer in other lymph nodes, such as those near the collarbone and behind the breastbone, may cause false-negative results.
1. Pain and Discomfort
Pain: Mild pain or discomfort in the area where they removed the biopsy. This usually goes away in a few days or weeks and might be treated with over-the-counter pain medicines.
2. Swelling (Lymphedema)
Lymphedema The most serious potential SSNBR is swelling due to a blockage of lymphatic fluid in the tissues (lymphedema). This happens when the sentinel lymph node is removed and hence disrupts the lymphatic drainage system. Although the risk is less than a complete lymph node dissection, lymphedema can still develop if additional lymph nodes are taken out with SLNB. Signs and symptoms can include swelling, heaviness, or tightness in a limb or area of body.
3. Infection
Just like all surgical procedures, infection at the site of removal of lymph node is another possibility. These signs of infection which may be present include a redness and warm feeling around the wound or burning on urination, increased pain on motion as might occur with appendicitis: swelling between te scrotal sac siemed to herald multiple signing up., sometimes discharge from an incision site. In general, such infections are rare and can be easily treated with antibiotics.
4. Seroma (Fluid Buildup)
On occasion a seroma, which is like a fluid sac, will develop under the skin in the area of lymph node removal. Seromas tend to disappear on their own however, in some cases, they can cause discomfort or last for long periods of time and may therefore need draining by a healthcare professional.
5. Bruising and Bleeding
Bruising may occur around the biopsy site and infrequently, there may be excessive bleeding. Occurrence of this side effect is usually minor although it could be more common in those patients taking blood thinning medication such as aspirin.
6. Numbness or Nerve Damage
It is not uncommon for patients to have some numbness, tingling, or burning in the biopsy area along with nerve irritation or injury damage during the procedure. Image InterpretationNerve injury is not common, but may occur when areas such as the neck or underarm (axilla) are examined.
7. Allergic Reaction to Dye
The sentinel lymph node is identified during SLNB by injecting blue dye or a radioactive tracer. In rare instances, allergic reactions to the blue dye may develop in patients: rashes, urticaria or anaphylactic shock. These are unlikely to happen and when they do, can be controlled as long as early intervention is instituted.
8. False Negative Result
A false negative rate of 10-20% with SLNB implies that a negative biopsy in the sentinel lymph node does not necessarily rule out the possibility that cancer has spread. This can cause a delay in the treatment of melanoma if cancerous lymph nodes are not detected early on.
9. Scarring
SLNB may be used to remove one lymph node, five lymph nodes or more during the operation and therefore depending on the volume, SLNB may induce a small scar at the biopsy site like any surgical procedure. The size of the incision will be determined by the position of the lymph nodes and style in which your surgeon operates. While there is a risk of scarring, with time most scars will go on to be very small.
10. Fatigue
After the procedure, some patients might feel tired or unwell in a kind of anesthetic hangover. Completely normal and it usually lasts a few days.
For the most part, sentinel lymph node biopsy is a safe procedure and most patients will recover fairly quickly without any major side effects. Still, it may be best to talk with your doctor in advance if you have any worries and especially if you are being treated for infections or taking medications that can affect how well the skin heals.
Why SLNB is Crucial for Melanoma Patients
SLNB holds a crucial role in the staging and management of melanoma. The overall 5-year survival rate for localized melanoma (when the disease has not spread beyond the skin) is about 98%. But once it has spread to other parts of the body, AML five-year survival rates plummet to 22%.
SLNB helps doctors determine the stage of the cancer by identifying whether melanoma has spread to the lymph nodes. This information is essential as the treatments at different stages vary significantly. Patients with localized melanoma may require surgical excision alone but if the disease has involved the nodal basin, additional therapies, including immunotherapy, targeted therapy or lymph node dissection are necessary.
What happens if melanoma has spread to the lymph nodes?
When melanoma has spread to the lymph nodes, it means that it is no longer where it started on the skin; the cancerous cells have traveled into the lymphatic system. This is a moderate phase of the disease and requires more vigorous treatment. And then it usually just continues like this from there:
Recovery time from a sentinel node biopsy varies among patients, depending on individual healing processes and whether other surgeries were performed alongside the biopsy.
1. Staging and Prognosis
Spreading to the lymph nodes usually “upstages” melanoma, changing a patients prognosis and treatment recommendations. When cancer is in the lymph nodes, the melanoma is usually defined as stage III (melanoma) and is considered regional disease. It is also based on the number of lymph nodes that contain cancer, how much the tumor has spread into the lymph nodes, and other factors indicating whether or not cancer has spread beyond the lymph nodes.
2. Radical Neck Disection; RND Complete Lymph Node Dissection
If a sentinel lymph node biopsy indicates the presence of melanoma in one or more lymph nodes, a doctor may suggest that the operation be followed by a complete lymph node dissection (CLND). When cancer cells spread, they first move to the sentinel nodes—the lymph nodes closest to the original tumor—which need to be removed and tested in order to properly stage and treat the disease Part of this is taking out more lymph nodes in the affected area to make sure that it has not moved on. But newer studies, including the MSLT-2 trial, show that in many cases, watchful waiting and scanning can replace full dissection without impacting survival.
3. Systemic Treatments
When melanoma spreads to the lymph nodes, local treatments like surgery may be less likely to cure the disease. In most cases, it is recommended that systemic treatments are used to target the cancer cells which might have spread elsewhere in the body. These treatments include:
Immunotherapy: Drugs to help the immune system to kill cancer. This can be with agents such as a checkpoint inhibitor pembrolizumab (Keytruda) or nivolumab (Opdivo).
Targeted Therapy: These are used solely for melanoma patients with certain genetic mutations in the melanoma (like BRAF or MEK mutations) and this treats the melanoma by blocking growth and spread of cancer cells using drugs such as vemurafenib or dabrafenib.
Chemo: A less popular melanoma treatment than in the past, chemo may sometimes be an option for advanced stages of melanoma that have been resistant to other treatments.
4. Radiation Therapy
Post-surgery, in few cases, radiation therapy may be advised to the lymph nodes which will help decrease the chance of the disease returning. This is most helpful if either there is a lot of tumor in the lymph nodes or very many nodes are involved.
5. Close Monitoring
Following lymph node involvement, patients will need to be closely observed for any potential recurrence or spread to distant organ sites. It tells you where the bodies, or the tumors, are supposed to be looked for in routine imaging tests like CT and PET scans or MRI together with simple observations from physical examination aided with blood work.
6. Prognosis
Melanoma with lymph node spread is a more severe prognosis than localized melanoma, but it is curable. For localized melanoma, the 5-year survival rate is approximately 98%; however, once the disease has spread to the lymphatic system and results in Stage IIIA cancer, 5-year survival drops to around 63%, even lower for additional complications involving more lymph nodes or tissue involvement. Yet, thanks to immunotherapy and targeted therapy, many of these stage III melanoma patients are now thriving.
In general, lymph node positive melanoma represents local spread and requires broader therapy to reduce disease and prevent further dissemination. Many can achieve longer survival and a better quality of life with improved treatment.The Importance of Surgical Excision in Melanoma Treatment
The primary treatment for melanoma involves wide surgical excision, with the goal of removing the entire tumor along with a margin of healthy tissue. The extent of the excision is determined by the melanoma’s Breslow thickness, which measures the depth of the tumor. Thin melanomas (less than 1 mm in thickness) require a smaller surgical margin, while thicker melanomas may require a larger excision.
Sentinel nodes are also critical in breast cancer, as they are the first lymph nodes to which breast cancer cells may spread, guiding treatment approaches.
In some cases, a positive SLNB result may lead to a more extensive lymph node dissection, where more lymph nodes are removed to prevent the spread of melanoma. However, recent studies, such as the MSLT-2 trial, have questioned the routine use of complete lymph node dissection, as it may not always lead to better survival outcomes.
Timing and Surgical Margins
Another important point is timing for treatment of melanoma. It has been demonstrated through previous studies that putting off surgery for melanoma by over 90 days results in increased rates of mortality, no matter the stage. The study found that even among patients with early-stage melanoma, defined by tumors thinner than 1 mm, delay of more than a month was tied to worse consequences.
Surgical margins are also another key element in melanoma clearance. Thin melanomas often have margins of 1 cm considered adequate for clearance, while wider margins are usually indicated for intermediate and planar/thick melanomas. Studies have demonstrated that increased margins can be used in managing melanoma to impact melanoma-specific survival but a definitive size is still being investigated through on-going clinical trials.
Who Should Have SLNB?
Intermediate thickness melanomas (1.0-4.0 mm) and select high-risk thin melanomas should also receive a SLNB. A few decades later, SLNB is first and foremost a staging procedure for patients with thick melanomas (> 4 mm) with marginal (at best) therapeutic utility. In such cases, the physicians may do confirmation imaging prior to surgery to better inform treatment strategies.
The Future of Melanoma Treatment
The treatment of melanoma has been revolutionized, in part due to the use of immunotherapy and targeted therapies. Although SLNB remains critical in melanoma staging, the approach to melanoma is rapidly changing. Advances such as adjuvant therapies (therapy given after surgery to reduce the risk of recurrence) are making a major difference for patients with melanoma that has spread. Finally, progress in the field of non-invasive treatment approaches like isolated limb perfusion and infusion therapy adds to the armory for patients with locally advanced disease.
Conclusion
The study was important because in melanoma patients, sentinel lymph node biopsy is a crucial step for both determining disease spread and guiding how it should be treated. Now more than ever, early detection and careful staging are key in an era of increasing global melanoma incidence. Our patients are offered the most innovative treatments for melanoma, including state-of-the-art SLNB techniques in order to secure the best possible results.
For more information or any questions regarding melanoma and SLNB contact if you are a candidate for this procedure, please call us to schedule a consultation.
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