If these first lymph nodes (sentinel lymph nodes) are cancer-free, there's a good chance that the melanoma has not spread beyond the area where it was first discovered.

CNN: Melanoma

Cancer can still recur or spread, even if the sentinel lymph nodes are free of cancer.

CNN: Melanoma

To determine whether your melanoma has spread to nearby lymph nodes, your surgeon may use a procedure known as a sentinel node biopsy.

CNN: Melanoma

Sentinel node biopsy works on the principle that a few of the underarm nodes are first in line to host the spreading cancer cells.

BBC: 'One stop shop' for cancer