Stage IIIA colorectal cancer; shows a cross-section of the colon/rectum and a two-panel inset. Each panel shows the layers of the colon/rectum wall: mucosa, submucosa, muscle layers, and serosa. Also shown are a blood vessel and lymph nodes. First panel shows cancer in the mucosa, submucosa, muscle layers, and 2 lymph nodes. Second panel  shows cancer in the mucosa, submucosa, and 5 lymph nodes.
Stage IIIA colon cancer. Cancer may have spread through the mucosa of the colon wall to the submucosa and muscle layer, and has spread to one to three nearby lymph nodes or tissues near the lymph nodes. OR, cancer has spread through the mucosa to the submucosa and four to six nearby lymph nodes.