What does the "T" in the TNM staging system measure?

The "T" in the TNM staging system refers specifically to tumor size. This part of the system assesses the primary tumor's characteristics, with a focus on its size and extent of invasion into nearby tissues. The measurement typically ranges from T1, indicating a small tumor, to T4, which indicates a larger tumor that may have invaded surrounding structures. This classification helps in determining the stage of cancer, which is crucial for planning treatment strategies and evaluating prognosis. Understanding tumor size is important because larger tumors may indicate more aggressive disease and could influence treatment decisions, such as the need for surgery or other interventions.