Non-sentinel lymph node status in melanoma: how important it is for cancer staging?

The authors analyzed the importance of non-sentinel lymph nodes in predicting the outcomes for patients with skin melanoma. 

In skin melanoma, sentinel lymph node (SLN) is the first lymph node (tiny, bean-shaped organ that helps fight infection) to which the cancer cells are believed to have spread (metastasis). The presence of SLN is determined by a procedure called sentinel lymph node biopsy (SLNB). It involves taking a tissue sample to determine whether the cancer has spread to the nearby lymph nodes. Patients who are found to have cancerous SLN undergo complete lymph node dissection (CLND – removal of the lymph nodes). However, the 5 year survival after CLND varies from 15% to 90%. Poor survival after CLND may be due to the spreading of cancer to the non-SLNs.

It is therefore important to understand the status of non-SLNs and how it could potentially determine the risk of cancer spread in melanoma. 

The authors aimed to determine how non-SLNs could predict outcomes in melanoma from two separate studies.

In the first analysis, data from 1,538 patients was studied. All patients had positive SLN and underwent CLND. The average follow-up time was 45 months.

Metastasis to non-SLNs was detected in 23% of patients. Overall, patients with cancer in non-SLNs had a 34% increased risk of dying from melanoma. This was independent of other risk factors. 387 patients with 2 to 3 positive (cancerous) lymph nodes among the non-SLNs had 39% increased risk of dying from melanoma. In contrast, patients with 4 or more positive lymph nodes among the non-SLNs were at a 25% reduced risk of dying from melanoma.

In the second analysis, data from 620 patients was studied. Out of these, 284 patients had negative non-SLNs and 336 patients had positive non-SLNs. Overall, patients with 2 to 3 positive lymph nodes among the non-SLNs had 59% increased risk of dying from melanoma. 

The authors concluded that non-SLN status of patients with 2 to 3 positive lymph nodes could be an important and independent predictive factor in determining outcome of skin melanoma.