I was recently asked about "Cancer Grading." This short post will update you on a few basic concepts as to how the medical community classifies and understands cancer. The proper identification of cancer, as well as its severity, helps clinicians determine the prognosis for the patient and the proper course of therapy. Keep in mind that some types of cancer have their own unique classification systems (e.g. Leukemia)
In general, first, one must understand the difference between "grading" and "staging."
Cancer Grading - The grading of cancer deals with how abnormal the cancer cells look under a microscope (Some systems just have three grades).
Grade 1: Tumor cells and tissue looks most like healthy cells and tissue. These are called well-differentiated tumors and are considered low grade.
Grade 2: The cells and tissue are somewhat abnormal and are called moderately differentiated. These are intermediate grade tumors.
Grade 3: Cancer cells and tissue look very abnormal. These cancers are considered poorly differentiated, since they no longer have an architectural structure or pattern. Grade 3 tumors are considered high grade.
Grade 4: These undifferentiated cancers have the most abnormal looking cells. These are the highest grade and typically grow and spread faster than lower grade tumors (1)
Grade GX - For some reason the doctors cannot assess the grade.
Cancer Staging - There are a number of ways to "stage" a cancer. Staging basically means that a medical provider is determining the extent or severity of your cancer. This measure helps medical providers with their understanding of how large the tumor is and how widely it has spread in the body.
Although individual cancers can have their own staging systems, the following is a typical generic description of staging: Each stage may have different divisions to help further clarify the cancer. The American Joint Committee on Cancer (AJCC) statement on cancer staging is now in its ninth edition.
Stage 0 - Abnormal cells are present but have not spread to nearby tissue. Also called carcinoma in situ, or CIS. CIS is not cancer, but it may become cancer.
Stage I through Stage III - Cancer is present. The higher the number, the larger the cancer tumor and the more it has spread into nearby tissues.
Stage IV cancer has spread to distant areas of the body (1)(2).
There are four approaches to staging that are applied at various times during one's experience with cancer. They are:
Clinical staging determines how much cancer there is based on physical examination, imaging tests, and biopsies of affected areas.
Pathological staging can be determined when a patient has surgery to remove a tumor. Pathological staging combines the results of both the clinical staging with the surgical results.
Post-therapy or post-neoadjuvant therapy staging determines how much cancer remains after a patient is treated with systemic therapy (chemotherapy or hormones) and/or radiation therapy prior to surgery or where no surgery is performed. This can be assessed by clinical staging guidelines after the therapy. It may also be assessed by pathological staging guidelines after surgery following the therapy.
Recurrence or retreatment staging is used to determine the extent of the disease if the cancer comes back after treatment. Recurrence or retreatment staging helps determine the best treatment options for cancer that has returned (3).
One final area that is helpful to understand concerning the staging of cancer is the
TNM system - The TNM is the most widely used cancer staging system.
Each letter stands for a different aspect of the cancer.
The "T" represents the extent of the original tumor.
The "N" represents the extent of spread to the lymph nodes.
The "M" represents the presence of metastasis (M).
There can be different divisions for each letter based on the type of cancer one has.
The T Category | ​The N Category | ​The M Category |
TX - Primary tumor cannot be evaluated | NX - Regional lymph nodes cannot be evaluated | ​ |
T0 - No Evidence as Primary Tumor | ​N0 - No regional lymph node involvement (no cancer found in the lymph nodes) | ​ |
Tis - Carcinoma inset (early cancer that has not spread to neighboring tissue | ​ | ​ |
T1-T4 - Size and/or extent of the primary tumor | ​N1-N3 Involvement of regional lymph nodes (number and/or extent of spread) | ​M0 No distant metastasis (cancer has not spread to other parts of the body) M1 Distant metastasis (cancer has spread to distant parts of the body) |
I know cancer (and its description) can be confusing. If I can help in any way, let me know.
https://www.cancer.gov/about-cancer/diagnosis-staging/staging