Lymph Node Management in Melanoma

Article:

Effiom D, Cohen S. Nodal Management in Melanoma: Is Nodal Staging Needed, What Is the Value, and What Is the Extent of Surgery? Surg Oncol Clin N Am. 2025 Jul;34(3):343-357

Understanding Lymph Node Management in Melanoma

When melanoma spreads, it usually goes to nearby lymph nodes first. How doctors check and treat your lymph nodes has changed dramatically in recent years, especially with new immunotherapy drugs. Here's what you need to know.

What is a sentinel lymph node biopsy (SLNB)?

The sentinel node is the first lymph node where melanoma is likely to spread. During SLNB, your surgeon injects a radioactive tracer near your melanoma site and uses a scanner to identify which node(s) drain that area. Only those 1–3 sentinel nodes are removed and examined under a microscope for cancer cells.

SLNB is much less invasive than the old approach of removing all regional lymph nodes. It's recommended for melanomas deeper than 0.8 mm or thinner ones with high-risk features (like ulceration).

Why is knowing your lymph node status important?

Finding melanoma in lymph nodes changes your stage from II to III and significantly affects prognosis. It tells you and your doctor how aggressive your melanoma is and helps guide treatment decisions. For example, 5-year survival drops considerably when lymph nodes are involved.

What if the sentinel node has cancer?

Historically, surgeons removed all remaining lymph nodes in that region (completion lymph node dissection). But landmark trials (MSLT-2 and DeCOG-SLT) showed this extensive surgery doesn't improve survival—only about 20% of those nodes actually contain cancer, and the surgery causes significant side effects like lymphedema (chronic swelling).

Today's approach: If your sentinel node is positive, you typically get systemic therapy (immunotherapy or targeted therapy if you have a BRAF mutation) rather than more surgery, unless nodes are clinically enlarged.

The game-changer: Adjuvant immunotherapy 

Powerful immunotherapy drugs (pembrolizumab, nivolumab) dramatically reduce melanoma recurrence when given after surgery for stage III disease. These drugs work by unleashing your immune system to attack remaining cancer cells.

Recently, these same drugs were approved for stage IIB/C melanoma—thick or ulcerated tumors without lymph node involvement. This raises an important question: if you can get immunotherapy without knowing your node status, why do SLNB at all?

Why sentinel lymph node biopsy still matters 

Several reasons:

1. Accurate prognosis: Knowing whether nodes are involved dramatically changes your survival outlook and helps you make informed decisions

2. Treatment decisions: Immunotherapy has serious side effects in 15% of patients, can be permanent, and costs ~$140,000/year. SLNB costs ~$7,000 and has minimal, temporary complications. Knowing your true risk helps you weigh whether the benefits of immunotherapy outweigh its risks

3. Neoadjuvant setting: When you receive immunotherapy before surgery for bulky stage III disease, examining lymph nodes afterward shows how well treatment worked—excellent response (less than 10% viable tumor) means 95%+ chance of staying disease-free and may allow skipping further treatment

Alternatives to SLNB? 

Researchers are studying whether gene expression profiling (analyzing tumor RNA) or ultrasound with needle biopsy can replace SLNB, but neither is accurate enough yet. Gene profiling misses positive nodes in about 20% of cases, and ultrasound only detects 46–82% of involved nodes—unacceptably low when the stakes are this high.

Take Home Message:

Sentinel lymph node biopsy remains the gold standard for staging melanoma. While not everyone needs it, it provides critical information that helps you and your doctor choose the right treatment intensity, avoid unnecessary immunotherapy toxicity and cost when safe to do so, and accurately understand your prognosis.