An Overview of Stage 1 Breast Cancer

Breast cancer, like other cancers, is staged. This is a determination of how much the cancer has spread. The stages help guide treatment and prognosis.

Stage 1 breast cancer is confined to the area where abnormal cell division began. It has not spread yet to anywhere else in the breast or body. It is further subdivided into Stages 1A and 1B. When detected at this early stage, treatment is usually very effective and the prognosis is good.

Understanding what a stage 1 tumor is, what treatment options you have, and your prognosis can help empower you and calm your fears. Read on to find out more.


Stage 1 breast cancer is the earliest stage of what's considered invasive breast cancer. "Invasive" does not mean that the cancer has invaded other areas of your body. It means that the cells in your tumor have infiltrated the area past what's called the basement membrane.

When a tumor first begins, it has not yet grown past this membrane and isn't considered cancer, but rather carcinoma in situ. These tumors are referred to as stage 0 tumors. Carcinoma in situ is 100% curable with surgery since the cells are completely contained.

Stage 1 tumors are the earliest stage of invasive breast cancer. These tumors are small, and if they have spread at all to lymph nodes, the spread is only microscopic.


To understand how your healthcare provider determines the stage of your cancer, and if you have a stage 1A or stage 1B tumor, it's helpful to know a little about something called the TNM system of classification.

  • T = Tumor Size: All stage 1 cancer is T-0 or T-1, meaning your tumor is 2 centimeters (cm, roughly an inch) or less in diameter.
  • N = Nodes: All stage 1 cancer is N-0 or N-1mi. N-0 means it has not spread to any lymph nodes. N-1 means that it has spread to lymph nodes nearby. The "mi" means there are micrometastases, which can only be seen under the microscope. Micrometastases measure between 0.2 millimeters (mm) and 2 mm (0.2 cm) in diameter.
  • M = Metastases: M-0 means that cancer has not metastasized (spread to other areas of the body).

Thus, using the TNM system, stage 1 cancers are defined as follows:

Stage 1 Breast Cancers
Stage 1A: T1N0M0 The tumor is less than 20 mm (2 cm) in size and there is no spread to lymph nodes.
Stage 1B: T1N1miM0 The tumor is less than 20 mm (2 cm) in size and there are micrometastases in a nearby lymph node.
Stage 1B: T0N1miM0 There is no evidence of a primary tumor in the breast but there are micrometastases in a lymph node (usually in the armpit). This is less common.

It can be confusing and a little alarming if you read your pathology report and note that it says that cancer has "metastasized to lymph nodes." This does not mean that you have metastatic breast cancer (stage 4 breast cancer). You can have lymph node metastases even with early-stage disease.

Overall, stage 1 tumors are those that are smaller than an inch in diameter and either do not have lymph node involvement or have spread to nearby lymph nodes only on a microscopic level. Once you know the stage of your breast cancer, there are several more things that will be considered in selecting the best treatment options for you.

Tumor Grade

Tumor grade is a number that describes the aggressiveness of a tumor. Pathologists look at the cancer cells from a biopsy and/or surgery under a microscope to determine things such as how actively cells are dividing. Tumors are then given a grade of 1, 2, or 3, with 1 being the least aggressive and 3 being the most aggressive.

Your tumor grade doesn't necessarily tell you what your prognosis will be, but it does help you and your healthcare provider choose the most appropriate treatments.

Receptor Status

You'll also need to know your tumor's receptor status. Receptors are proteins found on the surface of cancer cells that can tell what fuels the cell's growth and division. The three types you'll hear about are:

  • Estrogen receptors
  • Progesterone receptors
  • HER2

Once your tumor cells are tested, you'll be told whether it's:


Treatment options for stage 1 breast cancer fall into two main categories:

  • Local treatments: These treat cancer at the site and include surgery and radiation therapy.
  • Systemic treatments: These treat cancer throughout the body and include chemotherapy, hormonal therapy, targeted therapy, and immunotherapy.

If a tumor is very small, local treatments are usually all that's required. If the tumor is larger, more aggressive (has a higher tumor grade), has spread to lymph nodes, or has a molecular profile that indicates it's more likely to spread, systemic treatments are usually recommended.

With stage 1 breast cancers, the use of systemic therapy is considered adjuvant (add-on) therapy. The goal is to eliminate any cancer cells that may have spread beyond the breast but are too small to be detected.

Work with your healthcare provider to weigh the pros and cons of each option for your situation.

Breast Cancer Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Old Woman


Surgery is recommended for the majority of stage 1 cancers. Options include either a lumpectomy (removal of only part of the breast) or a mastectomy (removal of the entire breast). People choose one over the other for a number of reasons, and it can be a very personal choice.

If you choose a lumpectomy, following up with radiation therapy is usually recommended.

If you opt for a mastectomy, your healthcare provider will talk to you about the option of breast reconstruction. Skin-sparing surgery is becoming more common. In this procedure, an implant or an expander is often placed at the same time as your mastectomy. In addition, depending on your risk factors, you may need to weigh the risks and benefits of having a single vs. double mastectomy.

In addition to discussing the efficacy of these options with your healthcare provider, be sure to also talk about what you can expect cosmetically with each procedure.

Sentinel Node Biopsy

A sentinel node biopsy may be done before your surgery. In the past, several lymph nodes were usually removed and then examined under the microscope, but it's now possible to determine which lymph nodes cancer will spread to first and sample only those nodes.

If your lymph nodes are positive, it means the tumor has a higher chance of spreading to other organs or distant parts of the body. Often, chemotherapy is recommended to get rid of any cells that have spread.

Radiation Therapy

If you have a lumpectomy, radiation therapy is usually used to treat your remaining breast tissue.

Radiation can be done after both lumpectomy and mastectomy. Even with mastectomy, the surgeon is not able to get every single cancer cell. Radiation helps to kill cancer cells that may have been left behind or those that are too small to be seen.


Chemotherapy is sometimes used as an adjuvant treatment for stage 1 breast cancer.

The purpose of chemotherapy is to treat any cancer cells that may have strayed from your breast before they can grow into metastases.

The use of chemotherapy is also very dependent on the receptor status of the tumor. In a patient who is HER-2 positive or triple negative, chemotherapy is often used even if the lymph nodes are completely negative.

However, it's traditionally been difficult to determine who will benefit from chemotherapy, and it's especially difficult with node-negative stage 1 breast tumors that are positive for hormone receptors and negative for HER-2.

The Oncotype Dx Recurrence Score or MammaPrint are genomic tests that can be helpful in determining who should undergo chemotherapy. Those who score higher on the test are at higher risk for recurrence and chemotherapy can increase their survival rates. Those with low scores, meanwhile, are not likely to benefit from chemotherapy.

However, these tests are only used in patients with estrogen and/or progesterone positive tumors that are also HER-2 negative. They are not used in patients with triple negative or HER-2 positive breast cancer. 

Since some of the long-term potential side effects of chemotherapy can be severe—such as heart damage or failure and secondary leukemia—it's important to weigh the possible risks and benefits. Talk with your healthcare provider about the risks of each recommended chemotherapy drug and what it may mean for you.

Hormone Therapies

If your tumor is estrogen receptor-positive, hormonal therapy is usually recommended following primary treatment with surgery, chemotherapy, and radiation. The purpose is to reduce the risk of the cancer coming back.

Estrogen receptor-positive tumors are more likely to have a late recurrence (more than five years after diagnosis). The drug tamoxifen is often used for premenopausal women. For postmenopausal women, treatment is usually an aromatase inhibitor such as Aromasin (exemestane), Arimidex (anastrozole), or Femara (letrozole). In some high-risk premenopausal women, an aromatase inhibitor is sometimes used along with drugs to suppress ovarian function.

HER2 Targeted Therapies

If your tumor is HER2 positive, a HER2-targeted medication such as Herceptin (trastuzumab) is usually started after primary treatment.

Clinical Trials

The only way progress is made in the treatment of breast cancer is through studying new drugs and procedures in clinical trials. Many myths about clinical trials abound, but the truth is that every treatment being used today was once studied in a clinical trial. If other treatments have failed, this may be an avenue to explore.

It is important to choose the treatments that are best for you, no matter what someone else may choose. It's also very important to be your own advocate for your cancer care. Patients and healthcare providers are working together much more closely than in the past and you are a vital member of your cancer team.

Survival Rates

For those with localized, early-stage breast cancer who receive treatment with surgery and chemotherapy or radiation therapy, if recommended, the five-year survival rate is close to 100%.

Even so, going through treatment for stage 1 breast cancer can be challenging. Side effects are common, especially with chemotherapy, and fatigue is almost universal.

Follow-Up Care

After your initial breast cancer treatment is over, expect follow-up care to last another five years or possibly more. Ongoing treatments depend on multiple factors and may include:

It's important for you to know the signs and symptoms of a recurrence so you can alert your healthcare provider right away if you suspect the cancer has come back.


When you have stage 1 breast cancer, your emotions may span the spectrum from fear to worry to confusion to panic, sometimes in a manner of minutes. It's important to have an outlet for your feelings and to remember that it's OK (and understandable) to have a bad day.

You may encounter some people who say things like, "it's only stage 1," which can feel diminishing. While some may say this because they are unaware of the diagnosis's significance and the treatment involved, others may say this in an attempt to make you feel better (i.e., "at least it's not stage 4"). You are entitled to your feelings about your diagnosis, no matter what others say, but it may help to know these comments are well-intentioned.

One of the best things you can do for yourself is to gather a support network. Consider the people in your life you can lean on, both emotionally and practically. Even if you are feeling good through your treatment, it can be exhausting. Ask for help and allow people to give it to you.

Getting involved in a support group or online support community can be priceless. There is something very special about talking to others who are facing the same challenges you are. These communities also offer a chance to learn about the latest research on breast cancer, as there is nobody as motivated as those living with the disease.


Stage 1 breast cancer is very treatable with surgery, radiation, chemotherapy, or targeted therapies. It is considered early-stage breast cancer and the prognosis is good. Talk with your treatment team about what your diagnosis means and what treatment options may be best for you. Ask any questions you have—your treatment team is there for that reason!

Frequently Asked Questions

  • How often does stage 1 cancer metastasize?

    Breast cancer can recur and metastasize years to decades after the original diagnosis and treatment. Approximately 30% of women with early-stage breast cancer will eventually experience metastatic disease.

  • How long does it take for stage 1 breast cancer to develop into stage 2?

    It is not possible to determine exactly how long it will take for newly diagnosed breast cancer to progress from stage 1 to stage 2. It can happen within months if it is an aggressive high-grade tumor, or it can take longer. It's important to know that stage 1 breast cancer could have already been present for a while before being detected, so it may progress quickly.

  • What type of chemotherapy drugs are used for stage 1 breast cancer?

    The chemotherapy used for treating stage 1 cancer is determined on a case-by-case basis, guided by factors like hormone receptors and genetic mutations identified in the cancer cells.

  • How often does stage 1 breast cancer come back after treatment?

    If stage 1 cancer is treated comprehensively, the risk is fairly low. It can depend on characteristics of your breast cancer like hormone receptor status and size of the tumor. Local recurrence is more common, and about 7% to 11% of women with early-stage breast cancer have a local recurrence within the first five years. Your healthcare provider will recommend a surveillance schedule for you so that new breast cancer or a recurrence can be identified and treated as quickly as possible.

21 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Vaidya Y, Vaidya P, Vaidya T. Ductal carcinoma in situ of the breastIndian J Surg. 2015;77(2):141–146. doi:10.1007/s12262-013-0987-0

  2. Cserni G, Chmielik E, Cserni B, Tot T. The new TNM-based staging of breast cancer. Virchows Arch. 2018;472(5):697-703. doi:10.1007/s00428-018-2301-9

  3. Apple SK. Sentinel lymph node in breast cancer: Review article from a pathologist's point of viewJ Pathol Transl Med. 2016;50(2):83–95. doi:10.4132/jptm.2015.11.23

  4. Zhao YX, Liu YR, Xie S, Jiang YZ, Shao ZM. A nomogram predicting lymph node metastasis in T1 breast cancer based on the surveillance, epidemiology, and end results program. J Cancer. 2019 May 27;10(11):2443-2449. doi:10.7150/jca.30386

  5. Zhang BN, Cao XC, Chen JY, et al. Guidelines on the diagnosis and treatment of breast cancer (2011 edition)Gland Surg. 2012;1(1):39–61. doi:10.3978/j.issn.2227-684X.2012.04.07

  6. Kalinina T, Kononchuk V, Alekseenok E, et al. Expression of estrogen receptor- and progesterone receptor-regulating microRNAs in breast cancer. Genes (Basel). 2021 Apr 16;12(4):582. doi:10.3390/genes12040582

  7. National Cancer Institute. Breast cancer treatment (PDQ)—Health professional version.

  8. Sun ZH, Chen C, Kuang XW, Song JL, Sun SR, Wang WX. Breast surgery for young women with early-stage breast cancer: Mastectomy or breast-conserving therapy? Medicine (Baltimore). 2021 May 7;100(18):e25880. doi:10.1097/MD.0000000000025880

  9. Teven CM, Schmid DB, Sisco M, Ward J, Howard MA. Systemic therapy for early-stage breast cancer: What the plastic surgeon should knowEplasty. 2017;17:e7.

  10. Alba B, Schultz BD, Cohen D, Qin AL, Chan W, Tanna N. Risk-to-benefit relationship of contralateral prophylactic mastectomy: The argument for bilateral mastectomies with immediate reconstruction. Plast Reconstr Surg. 2019 Jul;144(1):1-9. doi:10.1097/PRS.0000000000005690

  11. Radiation therapy.

  12. Jeffe DB, Pérez M, Cole EF, Liu Y, Schootman M. The effects of surgery type and chemotherapy on early-stage breast cancer patients' quality of life over 2-year follow-upAnn Surg Oncol. 2016;23(3):735–743. doi:10.1245/s10434-015-4926-0

  13. Xin L, Liu YH, Martin TA, Jiang WG. The era of multigene panels comes? The clinical utility of oncotype DX and MammaPrintWorld J Oncol. 2017;8(2):34–40. doi:10.14740/wjon1019w

  14. Lumachi F, Santeufemia DA, Basso SM. Current medical treatment of estrogen receptor-positive breast cancerWorld J Biol Chem. 2015;6(3):231–239. doi:10.4331/wjbc.v6.i3.231

  15. American Cancer Society. Aromatase inhibitors for lowering breast cancer risk. Last revised December 16, 2021.

  16. Jiang N, Lin JJ, Wang J, et al. Novel treatment strategies for patients with HER2-positive breast cancer who do not benefit from current targeted therapy drugsExp Ther Med. 2018;16(3):2183–2192. doi:10.3892/etm.2018.6459

  17. American Cancer Society. Survival rates for breast cancer.

  18. Sisler J, Chaput G, Sussman J, Ozokwelu E. Follow-up after treatment for breast cancer: Practical guide to survivorship care for family physiciansCan Fam Physician. 2016;62(10):805–811.

  19. Hajian S, Mehrabi E, Simbar M, Houshyari M. Coping strategies and experiences in women with a primary breast cancer diagnosisAsian Pac J Cancer Prev. 2017;18(1):215–224. doi:10.22034/APJCP.2017.18.1.215

  20. Metastatic breast cancer.

  21. Cancer Treatment Centers of America. Recurrent breast cancer.

Additional Reading
Originally written by Pam Stephan
Pam Stephan is a breast cancer survivor.
Learn about our editorial process