Cancer spreads to tissue in what stage?

Cancer spreads to surrounding tissues primarily during the invasive stage, which is typically classified as stage II or higher in the tumor-node-metastasis (TNM) staging system. At this point, the cancerous cells have begun to infiltrate nearby structures and may not be confined to the original tumor site. This invasive behavior is a key characteristic that distinguishes malignant tumors from benign ones, which do not invade surrounding tissues.