Stage vs. Grade: What's the Difference?

Stage and grade sound alike. Reports often list them right next to each other. But they answer two completely different questions. Stage asks: how far has this cancer spread? Grade asks: how abnormal do the cancer cells look, and how fast are they likely to grow? You need both to understand your full picture. Neither one alone tells the whole story.

Stage describes the extent of your cancer. It typically runs from stage 0 up through stage IV. Stage 0 means abnormal cells that have not invaded surrounding tissue. Stage IV means the cancer has spread to distant parts of the body. Most solid cancers use the TNM system to determine stage. T stands for the size and extent of the main tumor. N stands for whether nearby lymph nodes are involved. M stands for whether the cancer has spread to distant organs. These three pieces combine into an overall stage number.

Stage is determined through a combination of imaging, physical exams, and pathology results from biopsies or surgery. It answers a geographic question. Where is the cancer, and how far has it traveled from where it started?

Grade is a different kind of assessment entirely. A pathologist looks at cancer cells under a microscope. These get compared to normal, healthy cells from that same tissue. Cells that still look fairly similar to normal cells are called low-grade, or well-differentiated. Cells that look very abnormal, disorganized, and unlike their tissue of origin are called high-grade. Doctors also call this poorly differentiated. Grade is usually scored on a scale. It is often 1 through 3, or 1 through 4, depending on the cancer type.

Grade is a behavioral question, not a geographic one. How aggressively is this specific cancer likely to grow and spread, based on what its cells look like right now?

Two tumors can share the same stage. They can still behave very differently, because of grade. A stage I tumor that is high-grade may need more aggressive treatment than a stage I tumor that is low-grade. The high-grade tumor is more likely to grow and spread quickly if left alone. The reverse also happens. A more advanced stage with a low grade can sometimes be managed less aggressively than the stage number alone might suggest.

This is exactly why your oncologist looks at stage and grade together, along with other pathology details. Leaning on either one alone would not plan your treatment or explain your outlook well.

Stage and grade are both based on population patterns. They describe what tends to happen to cancers that look like yours, spread like yours, in large groups of other people. Neither one predicts your individual outcome with certainty. Other factors shape your outlook too. These include your overall health, how your specific tumor responds to treatment, and increasingly, molecular and genetic features found through additional testing. They work alongside stage and grade, not instead of them.

• What is my stage, and separately, what is my grade?
• How do my stage and grade together shape the treatment you're recommending?
• Does my grade suggest this cancer is likely to grow quickly or slowly?
• Are there other test results, beyond stage and grade, that matter for my specific plan?

• UT MD Anderson — Cancer Grade vs. Cancer Stage
• National Cancer Institute — Tumor Grade
• American Cancer Society — Cancer Staging