TNM Classification

Issues of Concern

Cancer Grade Versus Stage

Cancer grading describes the microscopic appearance of the tumor's cells and tissue. Low-grade tumors have relatively normal-appearing cells and tissue structures. These tumors are considered well-differentiated. Higher-grade tumors have more abnormal-appearing cells and tissue that is structured abnormally. Higher-grade tumors are typically more aggressive and have a worse prognosis. They are described as poorly differentiated. The highest-grade tumors are termed undifferentiated. Cancer staging describes the gross appearance of the tumor. It can include tumor size, invasion, spread to local lymph nodes, or distant metastasis. Some staging systems also include the grade of the tumor. Many studies have demonstrated the value of cancer grade and stage in determining colorectal cancer prognosis.[5] Colorectal staging has been suggested to have the strongest association with survival.[6] Studies have further demonstrated considerable variation between pathologists in colorectal cancer grading, suggesting the importance of tumor staging for prognosis.[7] 

Population-Based Versus Personalized Cancer Staging

While the TNM system is useful as a classification system for carcinoma on a population level, its utility has been questioned on the individual patient level. Therefore, more personalized approaches have been suggested, including adding a molecular classification to the traditional approach to augment its overall utility. The Eighth AJCC Cancer Staging Manual has taken the early steps of acknowledging the importance of molecular oncology.[8]

Clinical Significance

The TNM system helps to establish the anatomic extent of the disease, and the combination of the 3 factors can define the overall tumor stage. This method allows for simplification, with cancers staged from I-IV, with stage IV being the most severe stage. Stage 0 indicates carcinoma in situ, which is not considered cancerous but may become cancer. Stage V is used exclusively in Wilms tumors and occurs when both kidneys have involvement at initial diagnosis.[9] A simplified version of cancer staging and its relation to TNM classification is listed below: 

• Stage 0 - Indicates carcinoma in situ. Tis, N0, M0.
• Stage I - Localized cancer. T1-T2, N0, M0.
• Stage II - Locally advanced cancer, early stages. T1-T2, N1, M0.
• Stage III - Locally advanced cancer, late stages. T1-T4, N2-N3, M0.
• Stage IV - Metastatic cancer. T1-T4, N1-N3, M1.

Progressive cancer staging is associated with disease severity and decreased survival rates. Anal squamous cell carcinomas demonstrated an observed 5-year survival rate of 77% for stage I and only 15% for stage IV.[10] Colorectal carcinoma demonstrated a 5-year survival rate of 74% for stage I but only 5% for stage IV.[2]

Nursing, Allied Health, and Interprofessional Team Interventions

Cancer management is complicated and requires an interdisciplinary approach. Proper communication between medicine, oncology, surgery, pathology, and other services is paramount. Further, pharmacists, nursing staff, nutrition, social work, and case management should be closely involved in the care of these patients. Treatment can be curative or palliative, and approaches vary based on the stage of cancer. Approaches can include elements of surgical removal, chemotherapy, and radiation. All healthcare team members should coordinate and agree on the proper treatment course for the individual patient.