They also are learning how stray melanoma cells that have broken away from the original tumor can lie dormant in the body for 10 years or longer before suddenly exploding into a deadly tumor mass at a distant site.

First, they break away from the primary tumor.

To do so, malignant cells break away from the primary tumor and attach to and degrade proteins that make up the surrounding extracellular matrix (ECM), which separates the tumor from adjoining tissues.

Metastasis can occur when cancer cells break away from the primary tumor, where the cancer began.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form.