Grading and Staging of Cancer
After cancer is diagnosed, healthcare provides need to learn as much as they can about
it. This helps them to plan the best treatment and look at overall outcomes and goals.
For many types of cancer, part of this process includes figuring out the cancer grade
What does the grade of a cancer mean?
Histologic "grade" is used to describe what the cancer cells look like using a microscope.
Most cancers are graded by how much they look like normal cells. Low grade or grade
I tumors are well-differentiated. This means that the tumor cells are organized and
look more like normal tissue. High grade or grade III tumor cells are poorly differentiated.
This means that the tumor cells don't look like normal cells. They're disorganized
under the microscope and tend to grow and spread faster than grade I tumors. Cancer
cells that do not look well-differentiated or poorly differentiated are called moderately
differentiated, or grade II. In general, cancer cells are graded using this scale.
(Be aware that some may use grade 3 as the highest grade):
Grade X: grade isn't known
Grade 1: Well differentiated, low grade
Grade 2: Moderayely differentiated, intermediate grade
Grade 3: Poorly differentiated, high grade
Grade 4: Undifferentiated, high grade
What does the stage of a cancer mean?
Once cancer is diagnosed, your healthcare provider will do more exams and tests to
find out the size of the cancer and where it is. These exams and test will also help
tell whether the cancer has grown into nearby areas and if it has spread to other
parts of the body. This is called staging. The stage of a cancer is one of the most
important things to know when deciding on how to treat the cancer.
Each cancer, by organ, has its own staging system. In most cases, the stages are listed
as Roman numerals and can have a value of I through IV (1 to 4). The higher the number,
the more advanced the cancer is. Letters and numbers can be used after the Roman numeral
to give more details.
Stages of cancer (the following list is general; each tumor type has its own [and
often complex] staging system)
Stage 0 or carcinoma in situ. Carcinoma in situ is considered pre-malignant or pre-cancer. Abnormal cells are
found only in the first layer of cells in the place where the changes first started.
The cells do not invade the deepr tissues. These cells may become cancer over time,
so it's good to find and treat them before that happens. Most kinds of cancer do not
use this stage.
Stage I. Cancer is only in the cells where it first started and the area is small. This is
considered early stage and most curable.
Stage II. Cancer is in the organ where it first started. It may be a bit larger than stage
I and/or may have spread to nearby lymph nodes.
Stage III. Cancer in the organ where it first started. It may be larger than stage II and may
have spread to nearby lymph nodes and/or other nearby tissues, organs, or structures.
Stage IV. Cancer has spread to organs in other parts of the body (metastasized). There may be cancer indifferent organs, but it's still the same type of cancer
as where it first started. For instance, colon cancer that spreads to the liver is
not liver cancer, it's stage IV colon cancer with liver metastasis. The cancer cells
in the liver look like the cancer cells in the colon and are treated like colon cancer.
Recurrent. Recurrent cancer has come back (recurred) after it has been treated. It may come
back in the same area or in a different part of the body.
Higher numbers usually mean more extensive disease, larger tumor size, and/or spread
of the cancer beyond the organ where it first developed. Higher grade and stage cancers
tend to be harder to cure and often require more intense treatments.
Once a stage is assigned and treatment given, the stage is never changed. For example
a stage I cancer of the cervix is treated. Two years later, the same cancer has spread
and is now found in the lung. It is not now stage IV, but remains stage I, with recurrence to the lung.
The important thing about staging is that it determines the appropriate treatment,
helps healthcare providers make a prognosis, and allows for comparison of treatment
Cancer grade and stage can be very complex and confusing. Be sure to ask your healthcare
provider to explain these details about your cancer to you in a way you can understand.