Cancer cells ignore these cells and invade nearby tissues. Benign (non-cancerous) tumors have a fibrous capsule. They may push up against nearby tissues but they do not invade/intermingle with other tissues. Cancer cells, in contrast, don't respect boundaries and invade tissues.
Cancer cells differ from normal cells in many ways that allow them to grow out of control and become invasive. One important difference is that cancer cells are less specialized than normal cells. That is, whereas normal cells mature into very distinct cell types with specific functions, cancer cells do not
