Which factor is primarily used to determine stage grouping in the AJCC system?

• A. Patient age
• B. Tumor grade
• C. Extent of disease
• D. Histology

Answer: (C)

Extent of disease is used to determine stage grouping in the AJCC system. AJCC staging combines measures of how far the cancer has grown locally (the primary tumor extent), whether regional lymph nodes are involved, and whether distant metastasis is present (T, N, M). These factors together place the cancer into a stage from I to IV. Age, tumor grade, and histology describe other aspects of the cancer and can influence prognosis or treatment decisions, but they do not define the stage itself. For example, a small tumor confined to its organ with no metastasis is a lower stage even if the tumor cells look very aggressive, while a larger tumor with nodal involvement but no distant spread is a higher stage, regardless of the patient’s age or the tumor’s microscopic grade.