Tumor Grading and Cancer Staging

Understanding how severe a person's cancer is and how aggressive the tumor behaves is crucial for treatment. Because there are many types of cancer and tumors, doctors use systems to give a number to show how bad the cancer is (called cancer staging) and how abnormal the cells in the tumor look (called tumor grade). These numbers help doctors predict how the cancer might progress and guide the treatment plan for each patient.

A Tumor is Graded Under the Microscope

Biopsy

The process begins by obtaining a tumor biopsy from a patient and preparing samples either by formalin-fixation paraffin embedding (FFPE) or freezing in liquid nitrogen. The samples are then sectioned and stained, allowing the oncologist to assess the size, shape and organization of the tumor cells under a microscope.

Tumor Status (T)

Refers to the size/extent of main tumor. Higher the number, greater the size and spread.

Graded

The tumor is then graded depending on the unique histology, or cell pattern. A tumor grade typically ranges from 1 (well differentiated) to 4 (undifferentiated or anaplastic). Grade 1 tumors are well differentiated, grow slowly and are considered the least aggressive. Meanwhile, tumors with grades 3 or 4 are described as undifferentiated and the most aggressive in behavior.

Nodal Status (N)

Refers to the number and location of lymph nodes containing cancer. Higher the number, the more lymph nodes that contain cancer.

Stage

This is where cancer staging comes in. A cancer stage not only factors in the tumor grade, but also the tumor size, position, spread, number of tumors, cell type, and involvement of neighboring lymph nodes. There are four stages of cancer and are depicted in roman numerals from I to IV. Stages increase as the primary tumor grows and spreads into other parts of the body. In some cases, stage 0 may be used to describe neoplastic cells that are localized and not yet cancerous.

Metastasis Status (M)

Refers to the status of metastasis of the cancer to other parts of the body.

TNM staging system (Tumor, Nodes and Metastasis)

Tumor Status (T) Chart

TX: The primary tumor cannot be evaluated.

T0 (T plus zero): No evidence of a primary tumor.

T1: The tumor is located only in the thymus or has grown into the nearby fatty tissues.

T1a: The tumor has spread into fat surrounding the thymus or
T1b: The tumor has grown into the lining of the lung next to the tumor (called mediastinal pleura).

T2: The tumor has grown into the nearby fatty tissue and into the sac around the heart, called pericardium.

T3: The tumor has spread to nearby tissues or organs, including the lungs, the blood vessels carrying blood into or out of the lungs, or the phrenic nerve, which controls breathing.

T4: The tumor has spread to nearby tissues or organs, including the windpipe, esophagus, or the blood vessels pumping blood away from the heart.

Nodal Status (N) Chart

The “N” in the TNM staging system stands for lymph nodes. These tiny, bean-shaped organs help fight infection. Lymph nodes near where the cancer started are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.

NX: The regional lymph nodes cannot be evaluated.
N0: The tumor has not spread into lymph nodes

N1: The tumor may have spread to nearby lymph nodes.

N2: The tumor has spread to lymph nodes deep in the chest cavity or neck.

Metastasis Status (N) Chart

Finally, the “M” in the TNM system describes whether the cancer has spread to other parts of the body, called distant metastasis.

M0 (M plus zero): The disease has not metastasized.

M1: The tumor has spread to other organs near the thymus, such as the lung and blood vessels.

M1a: The tumor has spread to the lining of the lung, called the pleura, or lining of the heart, called the pericardium
M1b: The tumor may have spread to the lining of the lung or the heart.

Simplified TNM Chart

*These details are for reference only and should not substitute professional diagnosis or medical advice.