Sentinel lymph node in the context of melanoma metastasis

The authors determined the risk of disease progression in melanoma patients based on the status of sentinel lymph node (SLN). 

Classification of skin melanoma based on SLN is the standard procedure used to determine the course of treatment in melanoma patients. SLN is the first lymph node (tiny, bean-shaped organ that fights infection) to which the cancer cells are believed to have spread (metastasis). The presence of SLN tumors 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.

Most patients with SLN tumors (also known as positive SLN) undergo surgery to remove the ‘hottest’ lymph node. The hottest lymph node is the SLN most likely to experience tumor growth. Patients who do not have positive SLN will not require additional surgery or treatment.  

It needs to be determined whether disease progression in melanoma is affected by the sentinel lymph nodes which are not the hottest lymph nodes.

The authors aimed to determine the factors that affect disease progression in melanoma patients with hottest and non-hottest SLN tumors.

1,575 SLNs were analyzed in 475 patients. The average follow-up time was 59 months. 19% of patients had positive SLNs. Of these, 79% had cancer in the hottest SLN. From the 19 patients who did not have cancer in the hottest SLN, 14% had cancer in the second hottest SLN. 19% of patients with positive SLN had metastasis in lymph nodes other than the hottest SLN. Overall, disease progression occurred in 43% of patients with positive SLN, regardless of whether the hottest lymph node contained cancer. Among those who had negative SLNs, 3.4% developed cancer in the SLN basin (area around the SLN) and 11% developed cancer spread beyond the SLN basin. 

Patients with quick tumor growth were at a 2.4 times higher risk of dying. Less than 55% of patients with 1 positive SLN lived for more than 8 years. When tumor thickness (how far the tumor reached deep into the skin) was 1 mm or less, 25% of patients with positive SLN and 4% of patients with negative SLN died due to melanoma.

The authors concluded that metastasis of melanoma to lymph nodes was associated with disease progression and shorter survival regardless of the SLN being the hottest or not.