Cancer Grade and Cancer Stage

Stage vs grade

An area of confusion

When I was first diagnosed I didn’t understand the difference between cancer grade and cancer stage and I have since found that this is a common area of confusion. Once explained, the difference is easy to understand.

Cancer grade

In many cases the cancer grade is the first number a cancer patient may receive. It usually will come from a biopsy after the pathologist examines the cells found in the sample.

Simply stated, the cancer grade is a scale which designates how abnormal the cancer cells are. Cancer cells that look and organize more like healthy tissue are considered low grade tumors and are generally less aggressive. Prognosis is much better with low grade cancers.

Cancer cells that appear more abnormal, less like normal cells, are called high grade. They are less organized and tend to be more aggressive with a poorer prognosis.

Generally the continuum runs from grade 1 (cells looking most like healthy cells) to grade 4 (cells looking most abnormal, spreading faster than lower grade cancers). So grade refers to how cancer cells are organized and. therefore how aggressive they might be.

Cancer Stage

Stage, on the other hand, refers to how much the cancer may have spread. Is it contained within the tumor only or has it spread to other parts of the body? The most common staging system ranges from Stage 0 to Stage IV.

Stage 0 refers to abnormal cells that haven’t spread and are not yet considered cancer though they could become so in the future.

Stages I to III encompasses cancers that haven’t spread beyond the primary tumor. The difference between them has to do with how large the tumor is and how much it has spread.

Stage IV signifies cancer’s spread to distant parts of the body a process called metastasis.

An Example

Using my diagnosis of dedifferentiated endometrial carcinoma, there are actually two different types of cancer in the endometrium. The originating cancer – a well differentiated endometroid adenocarcinoma – is low grade and classified as grade 1. This was my original diagnosis. After my hysterectomy, the pathologist had a full sample and the determination was made that there was also another cancer form that was beneath the originating cancer and unavailable to the initial biopsy – dedifferentiated endometrial carcinoma, a high grade cancer bringing with it the label of grade 3. Because of its high grade, this form of cancer is considered quite aggressive. It is also very rare although my doc has been seeing more cases recently.

In addition, endometrial cancer is also described by how deep the cancer has invaded the myometrium. A designation of “a” is given to cancer with less than 50% invasion and “b” is given to cancers with 50% or more invasion. My invasion was measured to be 23% and therefore labeled as “a”.

Given these parameters, my cancer is a stage 1a with a grade of 3 or 1a3.

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