stage I adult soft tissue sarcoma of the retroperitoneum (… uh-DULT ... TIH-shoo sar-KOH-muh ... REH-troh-PAYR-ih-toh-NEE-um)
Stage I is divided into stages IA and IB. In stage IA, the tumor is 5 centimeters or smaller and is low grade or the grade is unknown. Low-grade cancer cells look more like normal cells under a microscope and grow and spread more slowly than mid-grade and high-grade cancer cells. In stage IB, the tumor is larger than 5 centimeters and is low grade or the grade is unknown.