Which statement best describes the purpose of the TNM staging system?

• A. It classifies cancer based on tumor size only
• B. It classifies cancer based on the tumor, lymph node involvement, and metastasis
• C. It classifies cancer based on chemotherapy response
• D. It classifies cancer based on patient age

Answer: (B)

TNM staging describes how extensive a cancer is by looking at three things: the size or extent of the primary tumor (T), whether regional lymph nodes are involved (N), and whether there is distant metastasis (M). This combination is used to assign an overall stage (I–IV) that helps predict prognosis and guide treatment. The statement that best describes the TNM system is that it classifies cancer based on the tumor, lymph node involvement, and metastasis. It’s not about how the cancer responds to chemotherapy or the patient’s age; and while tumor size is part of it, TNM also includes lymph nodes and metastasis to give a complete picture of disease spread. This framework is standard across many cancers to standardize staging and inform care decisions.