Undifferentiated or poorly differentiated tumors tend to be more aggressive in their behavior. They grow faster, spread earlier and have a worse prognosis than well-differentiated tumors. But there are exceptions for both types of tumors. Some poorly differentiated tumors grow no faster than well-differentiated ones.
High-Grade and Low-Grade Tumors There is another classification system that sometimes overlaps with the system based on differentiation . This system refers to tumors as "high-grade" or "lowgrade." A high-grade tumor is immature, poorly differentiated, fast growing and aggressive. A low-grade tumor is usually mature, well-differentiated, slow growing and less aggressive. The grading of tumors is used to help determine cancer prognosis.
