Stage IIIC includes: (T4a, N2a, M0); (T3-T4a, N2b, M0); (T4b, N1-N2, M0). T3: Tumor invades through the muscularis propria into pericolorectal tissues. T4a: Tumor invades through the visceral peritoneum (including gross perforation of the bowel through tumor and continuous invasion of tumor through areas of inflammation to the surface of the visceral peritoneum). T4b: Tumor directly invades or adheres to adjacent organs or structures. N1: One to three regional lymph nodes are positive (tumor in lymph nodes measuring 0.2 mm or more), or any number of tumor deposits are present and all identifiable lymph nodes are negative. N2: Four or more regional lymph nodes are positive. N2a: Four to six regional lymph nodes are positive. N2b: Seven or more regional lymph nodes are positive. M0: No distant metastasis. (AJCC 8th ed.) [from NCI]