Merkel Cell Carcinoma Diagnostic Overview

Sentinel Lymph Node Biopsy

Since Merkel cell carcinoma (MCC) often quickly spreads to nearby lymph nodes, the nodes are examined once a diagnosis is confirmed. If the physician sees or feels that nodes that are enlarged, or if imaging strongly suggest enlargement, the cancer may have spread to local lymph nodes. If nodes do not appear enlarged, a sentinel lymph node biopsy (SLNB) is a common way to determine whether the disease has reached the lymph nodes.

What is a sentinel lymph node?

What is a lymph node?

Lymph nodes are glands that are part of your lymphatic system where your white blood cells form, and where lymph, a clear fluid containing your white blood cells, is filtered.

Sentinel nodes are the first lymph nodes that drain lymph fluid from the primary tumor, and it is believed that when cancer spreads, it will show up first in these nodes. In most areas of the body, there are only one or two sentinel lymph nodes. In the head and neck, there are typically two to five sentinel lymph nodes.

What happens during an SLNB?

A sentinel lymph node biopsy is a minimally invasive procedure with a low risk of side effects. It provides important information to guide doctors in staging and treating the disease.

Here’s what to expect

  1. The medical team begins by injecting a tracer material into the tumor site to help the surgeon locate the sentinel nodes during the procedure. Sometimes the medical team will also inject a blue dye into the tumor so that the nodes appear blue during the procedure.
  2. Using an instrument that detects the tracer, the path from tumor to nearby sentinel nodes is mapped. Cancer cells from the tumor would likely follow this path.
  3. The sentinel nodes are removed and analyzed in a lab.
  4. If cancer cells are discovered, the surgeon may opt to remove all local lymph nodes or destroy them with radiation therapy. Often, both procedures are performed: the lymph nodes are completely removed followed by radiation to help prevent recurrence.

Benefits of SLNB

Since cancer cells travel to the lymph nodes in one of every three MCC cases, SLNB helps patients by:

  • Identifying where cancer cells may have spread.
  • Revealing cancer cells that are not visible and cannot be detected through physical examination or imaging.
  • Helping the doctor predict the patient’s chance of recovery, also known as prognosis. If sentinel nodes are clear, a patient has about an 80 percent five-year survival rate. If nodes are involved, the rate drops to about 50 percent.
  • Guiding the doctor to determine the best treatment options.
  • Preventing a local recurrence by removing or destroying cancerous nodes.