Every year, about 285,000 Americans are diagnosed with breast cancer, according to estimates from the American Cancer Society. Each diagnosis also includes specific information about the cancer’s stage, which is a measure of how much cancer is in the body and where it’s located, the ACS reports.
The cancer’s stage is determined by examining the characteristics of cancerous cells harvested from the breast tumor during a biopsy or lumpectomy. During a biopsy, a small sample of the suspicious growth is removed and examined in the lab. During a lumpectomy, the entire lump of suspicious tissue is extracted and tested.
“Stage is really just talking about the size of the tumor and whether it’s in the lymph nodes or not,” says Dr. Nikita Shah, medical oncology team leader for the breast cancer center at the Orlando Health Cancer Institute in Florida.
The most common type of staging system used by a pathologist — a specialized physician who examines the tissue — is called TNM, which assesses:
— T: The size of the original tumor.
— N: Lymph node involvement, meaning that cancer has been detected in lymph nodes near the tumor. Lymph nodes are small, bean-shaped structures that are a critical aspect of the immune system. They are typically the first place that cancer cells reach when the cancer begins moving from its original source to other organs.
— M: Whether the cancer has metastasized to distant parts of the body, such as the brain or bones.
[SEE: Breast Cancer Symptoms.]
Stages of Breast Cancer
There are five stages of breast cancer, stages 0 through 4, and generally speaking, the lower the number, the less the cancer has spread throughout the body.
— Stage 0.
— Stage 1.
— Stage 2.
— Stage 3.
— Stage 4.
Stage 0
Stage 0 describes noninvasive breast cancers, meaning that cancer has not been detected outside the part of the breast in which it started. This means that the cancer is well confined to its point of origin and is very early on its path of development. Dr. Michele Carpenter, the breast program director of the Center for Cancer Prevention and Treatment at Providence St. Joseph Hospital in Orange County, California says that stage 0 breast cancer “is not a lethal disease.”
There’s some debate as to whether stage 0 breast cancers are cancer at all, with some experts saying it’s not technically cancer but rather a “pre-cancer” that indicates the patient has an increased risk of developing breast cancer in the future and ongoing Providence St. Joseph Hospital and other preventive measures may be prescribed.
Stage 1
Stage 1 refers to invasive breast cancers. These are cancers that have broken through to or have invaded the surrounding breast tissue, but are still relatively small, less than 2 centimeters, Shah says.
Stage 1 cancers typically have not have not moved into the lymph nodes yet. In some cases, they may have only just begun spreading into the closest lymph node, called the sentinel lymph node. Some Stage 1 cancers require chemotherapy treatment, Carpenter says.
Stage 2
Stage 2 breast cancers are larger than stage 1 tumors. In some cases, lymph nodes beyond that first sentinel lymph node may also be involved. Shah says a stage 2 designation may be warranted “because the tumor is bigger in size or there are lymph nodes involved or both.”
“This stage may require chemotherapy more often than stage 1,” Carpenter says.
Stage 3
Stage 3 is considered an advanced but treatable stage of breast cancer. In stage 3 breast cancer, also called “locally advanced breast cancer,” many lymph nodes close to the breast where the tumor started have cancer in them and/or the tumor is quite large — larger than 5 centimeters. It may have also spread to the skin or chest wall near where the original tumor started. The good news is that the cancer hasn’t yet spread to other organs, such as the brain, bones or lungs, which are all common metastasis locations for breast cancer.
“This kind usually needs chemotherapy,” Carpenter notes.
Stage 4
Stage 4, also called metastatic breast cancer, is the last stage of breast cancer. If you’ve been diagnosed with stage 4 cancer, this means that “the cancer has spread beyond the local lymph nodes and breast to other areas, which may include the bones, the lung, the abdomen and the liver. This stage is considered incurable, but today with all the treatments we have, it’s treatable as long as the cancer responds appropriately,” Carpenter says.
“Patients have lived many, many years with stage 4, but most of the time need continuing treatment,” she says.
[SEE:How Do I Read My Breast Cancer Biopsy Report?]
Prognostic Factors
While these numbers provide an understanding of how the cancer is moving in the body, the stage number is just one piece of the puzzle. In 2018, the American Joint Committee on Cancer, a group of cancer experts who develop guidelines around how cancer is classified and communicated, updated its staging system for breast cancer. Where prior to 2018, breast cancer was staged by the three characteristics of the tumor, today the system is more complex and takes into account additional characteristics of the tumor.
Shah says these additional factors provide a more nuanced understanding of a particular diagnosis that influence treatment choices along with “how we explain this to patients.”
The pathologist will assess several characteristics of the tumor, including:
— Estrogen receptor status. Tumor cells will be tested to determine what they use to grow, and for a majority of breast cancers, the hormone estrogen is what’s driving them. This type of cancer is designated as ER-positive.
— Progesterone receptor status. Progesterone is another that can also help cancer cells grow, and cells that have a higher number of these receptors on their surface are called PR-positive.
— HER2 status. If the cancer is making too much of a protein called HER2, or HER2/neu, then it’s said to be HER2-positive. HER2 stands for human epidermal growth factor receptor 2 and this protein can promote the growth of cancer cells.
— Grade. This information is used to classify how aggressive the tumor is expected to be and is based on an analysis of how the cancer cells look when compared to normal breast cells. Grade is listed as 1 through 3, with 1 being slower-growing cancer cells that look more like normal breast cells, while grade 3 cells look quite different from regular breast cells and are likely to grow and spread faster.
— Oncotype DX score. This piece of information only comes into play for patients whose cancer is determined to be ER-positive, HER2-negative and there is no cancer in the lymph nodes. The oncotype DX score is a genomic test that analyzes how active certain genes are in the cancer cell. These genes affect the behavior of the cancer and can give prognostic information about how likely it is to grow and spread. The Oncotype DX score is expressed as 0 to 100, with those patients scoring in the 0 to 25 range being said to have a low risk of recurrence; they don’t typically need chemotherapy. A score of 26 or higher indicates a high risk of recurrence so chemotherapy will likely be advised. But each situation has other factors at play and your doctor can discuss the specifics of your findings.
Your doctor may be less likely to use a stage number to describe your cancer and may emphasize these other factors, such as hormone receptor status instead. Shah says this can prevent patients from getting “caught up in the number because sometimes the number can be very misleading.”
[SEE:At-Home Exercises for Breast Cancer Recovery.]
Why Staging Matters
Carpenter says the new approach to staging provides a more comprehensive understanding of what’s going on with the disease and how it can be treated. They also provide a better understanding of the patient’s prognosis, or how well they’re likely to respond to a specific treatment.
Shah notes that “the stage is not what determines the behavior of the tumor and is not the determining factor for treatment. It’s just one of the things that we look at. Treatment is more frequently based on the biology of the cancer,” which includes things like the hormone receptor status and the grade.
No matter what type of breast cancer you have, the earlier it’s identified, the earlier your treatment can begin. Early treatment has been associated with better survival rates. This is why so many doctors and public health organizations urge that women get an annual or biannual mammogram starting at age 40 or 45, depending on your specific risk factors for developing breast cancer. (Talk to your doctor about when the right time to start and the appropriate frequency of screening for your individual situation.)
That said, even if you’ve been diagnosed with stage 4 breast cancer, take heart: Advances in management of late-stage cancer are leading to longer and better quality of life for many patients living with metastatic breast cancer.
There is clinical staging based on physical exam, imaging with or without biopsies of metastatic sites whenever applicable for patients who are getting chemo before surgery or have advanced disease. There is surgical staging which is generally more accurate for size of breast mass or lymph node spread. Then prognostic staging takes into account grade and hormone receptors for breast cancer because they impact recurrence rate and subsequently survival. Patients with triple negative breast cancer have higher stages compared to estrogen positive patients even if the mass is the same size. Prognostic staging is only accurate if patients follow the recommended treatment plans.
Shah says that in the past five years or so, a range of new treatments have become available that are prolonging life for those with late-stage breast cancer, and more advanced treatments are coming soon. “We’re going to be seeing a lot more of the targeted therapies where you find the mutation on the cancer cell and then target that mutation,” she explains.
In time, Shah thinks it will matter less where the cancer started (i.e. whether it’s breast cancer or lung cancer, for example) and the more important question will be what’s the mutation that’s driving it. She says she expects we’ll be “treating the mutation which drives the behavior of the cancer by blocking that mutation and stopping that cancer from growing, irrespective of where the tumor started from.”
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What Are the Stages of Breast Cancer? originally appeared on usnews.com
Update 03/25/22: This story was previously published at an earlier date and has been updated with new information.
