What does the term "grade" indicate in tumor pathology?

In tumor pathology, the term "grade" specifically refers to the level of differentiation of cancer cells. This classification system evaluates how much the cancer cells resemble normal cells in appearance and function. The grading system helps predict how aggressive the cancer may be. Higher-grade tumors typically indicate that the cells are poorly differentiated, which often correlates with a more aggressive behavior and a poorer prognosis. Conversely, lower-grade tumors tend to have well-differentiated cells that are more akin to normal cells and generally indicate a better prognosis.

The other options do not accurately represent what "grade" refers to in pathology. The severity of symptoms presented by the tumor pertains more to the clinical aspect of the disease rather than the biological characteristics of the tumor cells themselves. The age of the patient at diagnosis is a demographic factor, which does not influence the grading of tumor cells. Lastly, the size of the tumor falls under the category of "stage," which assesses the extent of cancer spread rather than the histological grade of the tumor cells. This differentiation is crucial for understanding the implications of tumor grading in patient management and treatment planning.