Stage III includes: IIIA: T3a, N0/N1, M0; IIIB: T3b, N0/N1, M0; IIIC: T3c, N0/N1, M0. T3a: Primary peritoneal cancer with microscopic extrapelvic (above the pelvic brim) peritoneal involvement with or without positive retroperitoneal lymph nodes. T3b: Primary peritoneal cancer with macroscopic peritoneal metastasis beyond pelvis 2 cm or less in greatest dimension with or without metastasis to the retroperitoneal lymph nodes. T3c: Primary peritoneal cancer with macroscopic peritoneal metastasis beyond the pelvis more than 2 cm in greatest dimension with or without metastasis to the retroperitoneal lymph nodes (includes extension of tumor to capsule of liver and spleen without parenchymal involvement of either organ). N0: No regional lymph node metastasis. N1: Positive retroperitoneal lymph nodes only (histologically confirmed). M0: No distant metastasis. (AJCC 8th Ed.) [from NCI]