Stage is determined by the tumor's size and grade and whether it has spread to nearby lymph nodes or distant sites. Several staging systems are used for adult soft tissue sarcomas, pediatric sarcomas and bone sarcomas.
The TNM system is useful to specialists, but a simplified staging system uses the grade of the tumor—the primary factor determining survival—to divide adult soft tissue sarcomas into four stages. Stages I, II and III, none of which involve spread to nearby lymph nodes or distant sites, are also divided into sub-stages A (tumors less than 2 in./5 cm in diameter) and B (tumors larger than that). Stage IV tumors have spread to regional lymph nodes (IVA) or to distant sites (IVB).
Grade is determined primarily by the percentage of dividing cells in the tumor. Grade 1 tumors are well-differentiated and have only a small chance of spreading to another site. Grade 2 tumors are moderately differentiated and have a less than 20 percent chance of spreading. Grade 3 tumors are poorly differentiated , meaning that they contain immature cells that divide rapidly. They have a greater than 50 percent chance of metastasizing.
Five-year survival is usually better than 75 percent for low-grade tumors and less than 25 percent for high-grade tumors.
