So you (or someone you love) has been diagnosed with cancer. What happens next? The likely thing that follows is your doctor will determine what’s called your cancer’s “stage.” This will inform how to best move forward with a treatment plan, which, in turn, will give you more info about your cancer, including what you can expect in the days ahead. We’re sure you have a lot of questions…and we, at HealthCentral, are here with the answers you need.
Why Is Cancer “Staged”?
Here’s staging in a nutshell: It describes where your cancer is located, how far your primary tumor (where your cancer started) has spread and to where, and its size.
Think of it as the geography of your cancer. Knowing where your cancer is and where it’s traveling in your body helps your cancer doc (oncologist) make key decisions about your treatment. Assigning it a stage number makes useful shorthand for mapping the cancer in your body.
And while you might think of your stage as being mainly about how serious your cancer is, it primarily tells you whether the tumor is in one place or whether it’s spread—and that, in turn, determines how serious it is.
For example, are your cancer cells still in the same spot they started growing as a tumor? That’s stage 1. Maybe you only need surgery.
Have they spread to your lymph nodes? That’s stage 3, and surgery alone might no longer be the best option; you might need chemotherapy and/or other treatments as well, to halt the disease’s progression through your body via the lymphatic system (our body’s extensive drainage network).
There Are Other Reasons Cancer Is Staged
- To consider whether other treatments might help: Knowing your cancer’s stage can assist your doctor in locating a clinical trial that may present another potential treatment option for you. Research is often one step ahead of current treatments.
- To communicate with your health care team: Depending on the progression of your cancer (was it caught early, or later, when it’s spread to more areas of your body?), your care team might include numerous doctors, like a surgical, medical, and/or radiation oncologist, other specialists, and your primary care doc. This team needs a standardized way to talk about your cancer with each other, so everybody’s on the same page when making decisions about your care.
- To help researchers: Healthcare pros who study cancer use stages to help them group patients, so they can look at effective treatments in similar cases.
- To help you understand your prognosis: Knowing your cancer stage can help you learn more about your diagnosis and better understand options.
How Does My Doctor Know What Stage My Cancer Is?
There are two main ways to sort solid tumor cancers like breast and prostate into stages: The TNM system, and the numbers staging system, which ranges from stage 0 to stage 4 (or 0-IV).
Whether you’re staged in both systems depends on the type of cancer you have. There are other staging systems for different kinds of cancer—we’ll go over those later.
Your doctor—along with pathologists, who test samples of the cancerous tumors, and radiologists, who use imaging to detect their placement and size—will consider physical exams, scans, laboratory tests, pathology reports, surgical reports, and other relevant information to stage your cancer.
Cancer can be staged at different points in your journey:
- Clinical staging. This stage is based on test results done before treatment, and can include physical exams or imaging, like MRIs, ultrasounds, CT scans, and X-rays.
- Pathological staging. This stage occurs after treatment and is the most precise measurement of the extent of cancer you have.
- Post-therapy staging. Before your tumor is surgically removed, your doctor will sometimes have you undergo treatments such as radiation therapy, hormone therapy, or immunotherapy to help shrink the mass—and this staging is done after those procedures but before surgery, so your surgeon will have a better idea of what they’ll face in removing the remaining tumor.
- Recurrence or retreatment staging. This staging is performed if you need retreatment for a cancer recurrence or disease progression.
What’s the TNM Staging System?
The TNM classification system isn’t new: It’s been around almost seven decades, but over the years, it’s been expanded to include factors like tumor markers/biomarkers and it continues to be updated regularly.
It’s often used by doctors and nurses to best understand the extent and type of cancer you have—a kind of language, if you will, for them to communicate and understand all aspects of your cancer, including treatment, care, and survivorship.
The American Joint Committee on Cancer (AJCC) oversees the current TNM classification in the U.S., and it convenes panels of oncologists and others every six to eight years to update the system’s standards for different cancers, based on the latest science and research. If you had breast cancer only a decade ago, for instance, you might’ve been a different stage in 2009 as you would today—with the exact same cancer tumor. The staging classification is more complicated now, but also more precise.
“TNM” stands for:
- T, Tumor: Simply enough, this describes the size and location of the primary tumor (where the cancer started).
- N, Node: This looks at whether that tumor has spread to the lymph nodes and if so, where and how many (the human body has between 500-700 lymph nodes, varying in each person).
- M, Metastasis: This part of the system determines if the cancer has moved to other parts of the body, and if it has, to where and how much.
Numbers after each letter can provide more details about the staged cancer type.
As an example: T1, T2, T3, T4 in breast cancer represent the increasing size of the tumor and how far it’s grown into neighboring tissue.
Letters can provide more info, too, like in prostate cancer, when specific stages like stage II cancer are drilled down further, into stage T2a, stage T2b, and stage T2c, each with different characteristics of this type of cancer.
In cancers where tumor markers, also called biomarkers (the two types are circulating tumor markers and tumor tissue markers), are available, the TNM classification includes these markers to help guess how the body will respnod to different treatments, as well as prognosis and other factors. (Not all cancers have tumor markers; the National Cancer Institute, NCI, has a helpful guide to common ones.)
Examples of circulating tumor markers include:
- calcitonin (measured in the blood), which helps in assessing treatment response and estimating prognosis, among other things, in a particular kind of thyroid cancer (medullary)
- beta-2-microglobulin (also measured in blood, plus urine and cerebrospinal fluid), useful in estimating prognosis and monitoring treatment response in cancers including multiple myeloma, chronic lymphocytic leukemia, and some lymphomas
- CA-125, (measured in blood too), to determine if cancer treatments are effective and if cancer has returned in ovarian cancer
Examples of tumor tissue markers include:
- estrogen receptor (ER) and progesterone receptor (PR) in breast cancer, to help determine if hormone therapy or targeted therapy might be effective treatment
- EGFR gene mutation analysis in non-small cell lung cancer, to determine treatment and prognosis
- PD-L1, which can help determine if a particular targeted therapy (immune checkpoint inhibitor, to be specific) is appropriate in a variety of cancer types, according to the National Cancer Institute (NCI).
These lists obviously exhaustive for all tumor markers/biomarkers and cancer types that researchers have discovered, but we'd run out of space if we listed all of them!
What Do the Stages 0 Through 4 Mean?
Once your doctor knows your TNM classification, they can then determine what "stage group" your cancer is in, if you have a cancer type that can be staged this way (not all cancers can be, including blood, bone marrow, brain, and gynecological cancers). This is the staging system so commonly referred to when discussing cancer—it’s the grouping of stages 0 through 4, typically represented by Roman numerals 0-IV.
This grouping is one final way health care professionals can understand your diagnosis, prognosis, and treatment potential by having an overall stage number in mind. It can help you, too, understand a less nuanced staging than the more specific TNM system.
The lower the number, the less advanced the disease. By stage IV, cancer is advanced and has spread, which means treatment might need to be more aggressive. But each case of cancer is different, even within the same stage, so while prognosis can tell you how sick you might be or become, other factors—like your health before treatment and even genetics—can play a role.
This staging system is also crucial if you want to be placed in a clinical trial. You need to have a staging group determined first, because it's commonly a more generalized way for researchers to assess where you belong in their study.
Yes, you can have stage 0 disease. The NCI defines this as carcinoma in situ (CIS), which is abnormal cells that may become cancer and spread into nearby normal tissue (“in situ” just means in its original place, so abnormal cells that haven’t spread—or in other words, a precancerous state).
The benefit of knowing you have this stage? Doctors can treat CIS before it becomes cancer. Treatment options differ based on the type of cancer you have. Let’s use melanoma as an example. In stage 0, melanoma is only in the epidermis, which is the outer layer of the skin, and hasn’t yet moved deeper into the skin. It’s typically removed surgically and is considered highly curable.
This stage of cancer is relatively small and is contained where it started—and also very often curable.
The treatment and five-year survival rates for stage 1 cancers are excellent, showing just how crucial early detection is. In general, the earlier the stage when you find cancer, the better your prognosis.
Let’s use melanoma as an example cancer. Stage 1 means it’s “local” (just like with stage 0), so it hasn’t spread. Within this stage, it’s divided into two parts: stage IA and stage IB, based on the side and thickness of the tumor, and it’s now moving into deeper layers of the skin. Treatment is also usually surgical removal.
At this point, cancer has started to spread, but it’s still on the earlier side of the disease.
For example, in stage 2 melanoma, it has spread beyond the outer layer of the skin into the thicker dermis layer. It’s slightly more likely to metastasize, but there’s no evidence that it’s moved into the lymph tissues, nodes, or organs. In melanoma specifically, this stage is still considered a local cancer (and with treatment, often surgery, has a five-year survival rate of more than 98%, but this isn’t representative of all cancers—this stat will vary).
Cancer has spread more than stage 2. We’ll stick with melanoma as our example cancer so you can see how an increased stage changes the treatment and survival rate drastically.
Stage 3 melanoma, considered a regional cancer, as opposed to local, has metastasized to nearby lymph nodes, lymph vessels, or skin.
Treatment varies depending on if the cancer can be surgically removed or not. The five-year survival rate for stage 3 melanoma is lower, unfortunately—63%.
This is also referred to as metastatic disease, when your cancer has advanced to the point that it’s spreading in multiple places in your body, and how much it’s spread from this stage versus stage 3 differs by cancer type and your individual case.
Treatment often includes surgery with immunotherapy or targeted therapy for advanced melanoma.
This stage is typically not curable (though there are certainly exceptions to that rule, and with some cancer types, you might live with the disease for many, many years). This is scary to hear, but know that treatments are advancing all the time, and doctors are finding more ways to make cancer a “chronic” illness, where you live with it far into the future.
Are There Other Ways Cancer Is Staged?
Cancers that don’t appear as solid tumors are generally cancers of the blood, and for those, there are other staging systems.
For instance, the Ann Arbor staging classification, a four-stage system, helps doctors figure out prognosis and best treatment options by examining the location, number of involved sites, and any systemic symptoms in Hodgkin lymphoma and non-Hodgkin lymphoid malignancies.
This staging can't be used for other cancers of the blood/bone marrow, however, including most types of leukemia, which don't have a clear staging system. Likewise, as we mentioned earlier, central nervous system tumors—so, brain tumors—don’t currently have a single staging system.
What’s most important to remember is that the stage of your cancer is one tool, of many, in your oncologist's care tool kit. It helps them better predict what your response to treatment might be—biomarkers can help make that prediction, as can past research showing how patients in your particular stage did on certain treatment regimes.
By giving doctors parameters to compare your situation to other patients in the same stage, you can get a lot of information, from how effective one treatment option is versus another…to what side effects you might experience, and what meds might help you handle them. All of this adds up to creating the most targeted, effective treatment plan for you.