In bladder cancer staging, which component describes distant metastasis?

• A. T
• B. N
• C. M
• D. Both T and M

Answer: (C)

The key idea is that the M component in the TNM staging system indicates distant metastasis. In bladder cancer, TNM breaks down disease status into T for the size and local invasion of the primary tumor, N for regional lymph node involvement, and M for spread to distant organs beyond the regional nodes. Metastasis means the cancer has traveled to faraway sites such as the liver, lungs, or bones, and that status is captured by M. So, distant metastasis is described by M (with M0 meaning no distant spread and M1 indicating distant metastasis). The T component describes how large or invasive the tumor is locally, and the N component describes regional lymph node involvement, not distant spread. A statement that both T and M describe distant metastasis would be incorrect, since each letter represents a different aspect of the disease.