Which factor is NOT typically included in a TNM classification?

In the TNM classification system, which is used for staging cancer, the factors assessed include Tumor size (T), Regional lymph nodes involvement (N), and Metastasis (M). The system focuses specifically on the anatomical features and spread of the tumor, providing essential information for treatment decisions and prognosis.

The size of the tumor is a critical component as it reflects the local extent of the malignancy. Lymph node involvement is also included in the classification, as the presence of cancer cells in lymph nodes can indicate a more advanced stage of the disease. Likewise, the presence of metastasis is a vital aspect since it signifies whether the cancer has spread beyond its original site.

However, patient age is not a factor considered in the TNM classification. While age can influence the prognosis and treatment options for cancer patients, it does not relate directly to the anatomical staging of the tumor itself. Thus, age is not included in the TNM system, making it the correct choice for this question.