Tests and procedures aid cancer diagnosis. On confirmation, few questions that instantly pop are - how advanced the cancer is, how much the cancer has grown and spread. These details encompass cancer staging and grading or in other words cancer staging and grading classify the advancement of cancer. Certain processes facilitate determining the cancer stage and grade. Details of cancer staging and grading help the doctor estimate the prognosis (outcome of the disease) and recommend to the patient the most appropriate treatment plan.
Cancer staging and grading
After determining the existence of cancer, the next step is to be familiar with four important aspects.
- The medical name of cancer or cancer type
- The stage of cancer
- The grade of cancer and
- Prognostic factors.
To determine the type of cancer, the origin organ or the organ the cancer initiated, the kind of cell from which the cancer is derived and the appearance of the cancer cells will be considered. This is followed by a diagnostic process, namely cancer staging and grading.
To get an accurate staging and grading evaluation, various tests will be recommended by the doctor. If cancer cannot be accurately staged through tests, an operation may be performed to look inside part or parts of the body. An operation may be done to remove the primary tumor also.
Cancer Staging: Refers to how invasive the cancer is.
Cancer Grading: How different the cells are from the normal cells.
Knowing cancer staging and grading is the precursor to determining the appropriate clinical attention. Detecting cancer at its nascent stage at low-grade is encouraging. Not only are there a wider range of treatment options, the chances of survival are also greater. On the other hand, higher the stage and grade, the worse would be its effect on the patient.
Importance of cancer staging and grading
Treatment of cancer and prognostic features are dependent on cancer staging and grading. Different stages of cancer may require different treatments, and different grades within each stage can also change the treatment plan. There are other aspects too.
- Know where the cancer is located (organ of origin and tissue type)
- Find how far it has spread (local, regional and distant spread)
- Whether affecting functions of other organs of the body
- Estimate patient's prognosis
- Look into patient's course of disease
- Assess the extent of cancer
- Determine appropriate treatment
- Determine tumor size
- Decrease the tumor burden
- Relieve symptoms
- Predict recurrence.
Relevance to medical professionals
- Easier for the medical team to communicate in a common terminology
- Standard way for the cancer care team to summarize the extent of a cancer's spread
- Easier to compare treatments with findings of research studies
Cancer staging types
There are two types of cancer staging, clinical staging and pathological staging.
Clinical staging: It involves physical examination of the patient. The doctor might look at or feel the part of the body that is affected. Imaging tests like X-rays, CT scans, MRIs, PET scan and Ultrasound, Endoscopy, biopsy or other tests that are deemed necessary form part of clinical staging. The aim is to know how much and where the cancer is in the body.
Pathological staging: Also referred to as surgical staging, this stage involves examining the tissue samples removed during surgery or a biopsy. The tissue is initially evaluated under a microscope.
Elements of Cancer staging
There are more than 100 different types of cancer. Various cancers have different staging classification. Though there is several cancer staging systems, the elements of almost all cancer staging are similar which are:
- Site of the primary tumor
- The size, depth and number of tumors
- The cellular make-up
- Activity of the tumor
- The involvement of lymph nodes
- The cell type and tumor grade
- The presence or absence of metastasis.
Ongoing research on the subject is likely to introduce new cancer staging methods. The two methods which are highly preferred are:
- For most solid tumors the TMN Staging and
- The Roman numeral or stage grouping for almost all cancer types.
TNM Staging: Tumor node metastasis system or the TNM system is accepted by the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC). TNM method describes the size of an original/primary tumor (T), whether the cancer has spread to the lymph nodes (N) and whether the cancer has spread to a different part of the body (M) (in medical terms 'metastasized').
Each cancer type is assigned a letter or number to describe the tumor, node and metastasis. To each of the three letters, namely T, N and M, a number is added to indicate the size and/or extent of the primary tumor and the degree/extent the cancer has spread. The numbers are helpful in categorizing the cancer more specifically. Additionally, a lower case 'c' or 'p' is used to denote if the cancer is in the clinical or pathologic stage.
T in TNM cancer staging:
TX: Is used if tumor cannot be measured.
TO: Means there is no evidence of a primary tumor.
Tis or Cis (carcinoma in situ): confirms the presence of abnormal cells but has not spread as yet. This stage may also be called stage 0.
T1, T2, and T3 & T4: T1 refers to an early stage and small tumor and as the number increases it means an advanced cancer stage. T4 means an advanced and large tumor.
N in TNM cancer staging:The N refers to lymph nodes or lymph gland, an organ of the immune system which is distributed throughout the body. There is a connection between the lymph nodes and cancer in this manner. When the cancer cells break away from a tumor, they can travel to other areas of the body through the bloodstream or the lymph system. If they choose to travel through the lymph system, they may end up in the lymph nodes. Thus cancer in nodes affects cancer stage.
N 0: N with a 0 means there is no cancer found in the lymph nodes near the cancer or nodes are not involved.
N1, N2, N3: means nearby or distant nodes show cancer and the numbers denote how many nodes are affected, their size and where they are.
NX: is assigned if the stage of the cancer is not clear.
M in TNM cancer staging
M in TNM cancer staging stands for metastasis which means spread of cancer from its primary site to other places in the body. There are four possible routes.
- Via lymphatic channels
- Via blood vessels
- Via body cavities
- Transplantation of the cancer (fragments of tumor cells through needles or surgical instruments during surgery and any diagnostic procedure)
Metastasis is dangerous. The chances of survival of cancer patients are grim at metastasis stage. Data indicates 60% to 70% of cancer patients are at this stage or have already initiated the process by the time of diagnosis.
M0: cancer has not spread to any other part of the body.
M1: cancer has spread away from primary tumor and into one or more areas of the body.
MX: the stage isn't clear.
Number staging system
This is another way of staging cancer. Some cancer like lymphoma, thymus and liver cancer may follow number staging system and not the TNM staging system. But in certain cancer types after the TNM description, an overall stage from 0 to 4 is assigned. The purpose is to identify whether the cancer is at an early or advanced stage. The higher the number, the more advanced the cancer.
0: carcinoma in situ or pre-cancer stage. The presence of a flat lesion with no invasion of malignant cells into the surrounding tissue is confirmed. There is a possibility of this developing into a full blown cancer. Some cancer may not go beyond this stage.
Stage 1: Presence of tumor confirmed but has not spread to the lymph nodes (early stage). The tumor is usually smaller than 2 cms.
Stage 2: The tumor is usually around 2-5 cms but is still localized.
Stage 3: The cancer has spread to a surrounding structure or to the regional lymph nodes. The tumors are fairly large measuring more than 5 cms. At this stage, the nearby lymph nodes are likely to be affected.
Stage 4: At this advanced stage, tumors may be of any size, will affect nearby lymph nodes and also metastasized to other organs or regions of the body. There is a possibility of a secondary cancer developing at this stage.
The numbers may have an alphabet as suffix to further define the cancer.
Other cancer staging systems
There are some cancers that grow and spread in a different way. These are staged differently. For example leukemia (cancer of the blood) has no solid tumor formation but affects the blood and bone marrow throughout the body. Likewise, cancer in and around the brain is staged differently. This is because these cancers have a higher percentage of spreading to other parts of the brain and not to the lymph nodes or other organs of the body. Yet another cancer for which a different staging system is used is the cancers of the female reproductive organs. For colon cancer, the stage used is the Dukes system. Cancer patients need to be aware of the cancer staging system.
Every cancer has a grade. Cancer grading is done after a biopsy (removal and examination of the tissue). The tissue samples are sent to a laboratory for analysis by a pathologist. The results are then graded by the pathologist.
Cancer grade indicates how slowly or rapidly the cancer can grow and spread its aggressiveness and malignancy. Cancer grade is determined by examining the cells under the microscope. A lower grade means slow-growing cancer and a higher grade means a fast-growing cancer. Low-grade tumor cells are almost like the normal cells. They look bland under the microscope. The same cannot be said about the high-grade tumor cells. They look large, different in size and shape.
Grade I: The cancer cells resemble normal cells both in size and shape. The cells are usually slow-growing. This grade is also referred to as well-differentiated stage.
Grade II: Also termed as moderately-differentiated grade, the cells do not resemble normal cells, are larger in size and varies in shape too. The cells grow rapidly.
Grade III: Referred also as poorly-differentiated grade, the cells look abnormal. They grow quickly in a disorganized and irregular pattern and spread aggressively.
Similar to cancer staging, cancer grading may vary for specific cancer types. For example to grade prostate cancer Gleason score or grade is adopted wherein a grade of 1-7 is allotted depending on how the cancerous cells look compared to normal cells.
Normal: score of 2 to 4 means cells look like normal cells with little danger of spreading quickly.
Aggressive: score of 8 to 10 indicate that the cells resemble normal cells but can become aggressive.
Intermediate: score of 5 to 7 pose intermediate risk.
A combination Gleason score is arrived at when the pathologist examines the most common tumor and the second most common pattern. The score are then combined to arrive at a Gleason score.
Right to Information
Every cancer patient has the right to know about cancer staging system. It is the responsibility of the medical and nursing staff to inform about the stage and grade to the patient and/or his/her close associate. The information enables patients to gain better insight about the proposed nature of treatment and what to expect in days to come.