Most cancers are classified into five stages, numbered 0 through IV. These stages describe how large a tumor is and how far it has spread in the body. Stage 0 means abnormal cells are present but haven’t invaded surrounding tissue, while stage IV means cancer has spread to distant organs. The higher the number, the more advanced the disease.
The Five Stages Explained
Each stage reflects a combination of tumor size, lymph node involvement, and whether cancer has traveled to other parts of the body.
- Stage 0: Abnormal or precancerous cells are present but haven’t spread beyond where they started. This is sometimes called “in situ,” meaning the cells are still in place. Many stage 0 findings are highly treatable or even curable with minor procedures.
- Stage I: The tumor is small and contained to one area. Cancer cells haven’t reached nearby lymph nodes or other organs. This is often called early-stage cancer.
- Stage II: The tumor is larger than in stage I, or cancer cells have begun to move into a small number of nearby lymph nodes. The cancer still hasn’t spread to distant parts of the body.
- Stage III: The tumor may be larger and has typically spread to multiple nearby lymph nodes or surrounding tissues. Despite being more advanced locally, the cancer hasn’t reached distant organs.
- Stage IV: Cancer has spread from the original tumor to distant areas of the body, such as the lungs, liver, bones, or brain. This is also called metastatic cancer.
Within each stage, doctors often use letters (like IIIA or IIIB) to provide more detail. So while there are five main stages, the actual classification can be more granular depending on the cancer type.
How Doctors Determine the Stage
Staging relies on a system called TNM, maintained by the American Joint Committee on Cancer (AJCC). Each letter captures a different piece of information. T describes the size and extent of the primary tumor, ranked from T1 (smallest) through T4 (largest or most invasive). N describes how many nearby lymph nodes contain cancer, from N0 (none) to N3 (many). M indicates whether cancer has metastasized to distant parts of the body: M0 means it hasn’t, M1 means it has.
Doctors combine these three values to assign the overall stage number. For example, a small tumor (T1) with no lymph node involvement (N0) and no distant spread (M0) would typically be stage I. A large tumor (T4) that has reached several lymph nodes (N2) but hasn’t spread distantly (M0) might be stage III. Any cancer with M1, regardless of tumor size, is stage IV.
Imaging scans, biopsies, blood tests, and sometimes surgery all play a role in gathering the information needed for staging. The TNM system is periodically updated. The AJCC recently shifted from publishing a static staging manual to a rolling “versioned” system, where individual cancer types get updated staging criteria as new evidence becomes available rather than waiting for an entirely new edition.
Cancers That Use Different Systems
The 0-through-IV framework applies to most solid tumors, including breast, lung, colon, and prostate cancers. But not all cancers fit neatly into this model. Blood cancers like leukemia and lymphoma behave differently because they don’t form a single solid tumor that grows and spreads in stages the way a breast or lung tumor does.
Lymphomas typically use a system called Ann Arbor staging, which tracks how many lymph node regions are affected and whether the cancer is on one or both sides of the diaphragm. Certain types of leukemia use systems named Rai or Binet, which focus on blood cell counts and which organs are enlarged rather than tumor size. If you’ve been diagnosed with a blood cancer, your staging system will look quite different from what’s described above, but the core idea is the same: it tells you how widespread the disease is.
Stage vs. Grade
People often confuse stage and grade, but they measure different things. Stage describes how far cancer has spread through the body. Grade describes how abnormal the cancer cells look under a microscope and how quickly they’re likely to grow. A low-grade tumor has cells that still resemble normal tissue and tend to grow slowly. A high-grade tumor has cells that look very abnormal and usually grow more aggressively.
Both stage and grade factor into treatment decisions and outlook. It’s possible to have a low-stage but high-grade cancer, meaning it hasn’t spread far yet but the cells themselves are aggressive. Your doctor considers both numbers together, not in isolation.
Why Stage Matters for Survival
Stage is one of the strongest predictors of how well treatment will work. The numbers make this clear. Across 17 major cancer types, the five-year survival rate for cancers caught while still localized (confined to where they started) is about 92%. When cancer has spread to nearby lymph nodes or tissues (regional), that drops to roughly 64%. When it has spread to distant organs, the five-year survival rate falls to around 15%.
The gap is dramatic for specific cancers. Pancreatic cancer caught at a localized stage has a five-year survival rate near 47%, but that drops to about 4% once it reaches distant organs. Lung cancer follows a similar pattern: 65% survival when localized, just 8% when distant. Kidney cancer, by contrast, maintains relatively strong survival rates even at regional stages (around 71%), partly because certain kidney cancers grow more slowly.
These numbers have been improving over time. A study published in the Journal of Clinical Oncology tracking trends across a decade found that survival gains were largest for cancers caught at the regional and distant stages, where newer treatments like targeted therapies and immunotherapies have had the biggest impact. Distant-stage survival across all 17 cancer types rose from about 11% to 15% over a ten-year period. That may sound modest, but it represents tens of thousands of additional people alive five years after diagnosis.
Can a Cancer’s Stage Change?
A cancer’s stage is typically assigned at diagnosis and stays the same, even if the disease later progresses. If a stage II breast cancer later spreads to the bones, it’s still referred to as stage II breast cancer with distant metastasis, not stage IV. This is because the original stage reflects the cancer’s biology at the time it was first found, which helps doctors compare outcomes and guide treatment decisions over time.
That said, doctors sometimes “restage” cancer using a prefix like “r” (for recurrence) or “y” (after treatment) to capture how the disease has changed. If you undergo chemotherapy before surgery, for instance, the surgical findings might show a different extent of disease than what imaging initially suggested. This restaging helps adjust the treatment plan going forward without erasing the original baseline.