Treatment of Breast Cancer Stages I-III

The stage (extent) of your breast cancer is an important factor in making decisions about your treatment. 

Most women with breast cancer in stages I, II, or III are treated with surgery, often followed by radiation therapy. Many women also get some kind of drug therapy. In general, the more the breast cancer has spread, the more treatment you will likely need. But your treatment options are affected by your personal preferences and other information about your breast cancer, such as:

  • If the cancer cells contain hormone receptors. That is, if the cancer is estrogen receptor (ER)-positive or progesterone receptor (PR)-positive.
  • If the cancer cells have large amounts of the HER2 protein (that is, if the cancer is HER2-positive)
  • How fast the cancer is growing (measured by grade or Ki-67)
  • Your overall health
  • If you have gone through menopause or not

Talk with your doctor about how these factors can affect your treatment options.

What type of drug treatment(s) might I get?

Most women with breast cancer in stages I to III will get some kind of drug therapy as part of their treatment. This may include:

  • Chemotherapy
  • Hormone therapy (tamoxifen, an aromatase inhibitor, or one followed by the other)
  • HER2 targeted drugs, such as trastuzumab (Herceptin) and pertuzumab (Perjeta)
  • Some combination of these

The types of drugs that might work best depend on the tumor’s hormone receptor status, HER2 status, and other factors.

Treating stage I breast cancer

These breast cancers are still relatively small and either have not spread to the lymph nodes or have spread to only a tiny area in the sentinel lymph node (the first lymph node to which cancer is likely to spread).

Local therapy (surgery and radiation therapy)

Surgery is the main treatment for stage I breast cancer. These cancers can be treated with either breast-conserving surgery (BCS; sometimes called lumpectomy or partial mastectomy) or mastectomy. The nearby lymph nodes will also need to be checked, either with a sentinel lymph node biopsy (SLNB) or an axillary lymph node dissection (ALND).

In some cases, breast reconstruction can be done at the same time as the surgery to remove the cancer. But if you will need radiation therapy after surgery, it is better to wait to get reconstruction until after the radiation is complete.

If BCS is done, radiation therapy is usually given after surgery to lower the chance of the cancer coming back in the breast and to also help people live longer.

In a separate group, women who are at least 70 years old may consider BCS without radiation therapy if ALL of the following are true:

  • The tumor was 2 cm (a little less than 1 inch) or less across and it has been removed completely.
  • None of the lymph nodes removed contained cancer.
  • The cancer is ER-positive or PR-positive, and hormone therapy is given.

Radiation therapy in this set of women still lowers the chance of the cancer coming back, but it has not been shown to help them live longer.

If mastectomy is done, radiation therapy is less likely to be needed, but it might be given depending on the details of your specific cancer. You should discuss if you need radiation treatment with your doctor. They may send you to a doctor who specializes in radiation (a radiation oncologist) for evaluation.

Neoadjuvant and adjuvant systemic therapy (chemo and other drugs)

For women who have a hormone receptor-positive (ER-positive or PR-positive) breast cancer, most doctors will recommend hormone therapy (tamoxifen or an aromatase inhibitor, or one followed by the other) as an adjuvant (additional) treatment, no matter how small the tumor is. Women with tumors larger than 0.5 cm (about ¼ inch) across may be more likely to benefit from it. Hormone therapy is typically given for at least 5 years.

If the tumor is larger than 1 cm (about ½ inch) across, chemo after surgery (adjuvant chemotherapy) is sometimes recommended. A woman's age when she is diagnosed may help in deciding if chemo should be offered or not. Some doctors may suggest chemo for smaller tumors as well, especially if they have any unfavorable features (a cancer that is growing fast; hormone receptor-negative, HER2-positive; or having a high score on a gene panel such as Oncotype DX).

After surgery, some women with HER2-positive cancers will be treated with trastuzumab (with or without pertuzumab) for up to 1 year.

Many women with HER2-positive cancers will be treated with trastuzumab (with or without pertuzumab) followed by surgery and more trastuzumab (with or without pertuzumab) for up to 1 year. If after neoadjuvant therapy, residual cancer is found during surgery, trastuzumab may be changed to a different drug, called ado-trastuzumab emtansine, which is given every 3 weeks for 13 doses. If hormone receptor-positive cancer is found in the lymph nodes, your doctor might recommend one year of trastuzumab followed by additional treatment with an oral drug called neratinib for 1 year.

Treating stage II breast cancer

These breast cancers are larger than stage I cancers and/or have spread to a few nearby lymph nodes.

Local therapy (surgery and radiation therapy)

Stage II cancers are treated with either breast-conserving surgery (BCS; sometimes called lumpectomy or partial mastectomy) or mastectomy. The nearby lymph nodes will also be checked, either with a sentinel lymph node biopsy (SLNB) or an axillary lymph node dissection (ALND).

Women who have BCS are treated with radiation therapy after surgery. Women who have a mastectomy are typically treated with radiation if the cancer is found in the lymph nodes. Some patients who have a SLNB that shows cancer in a few lymph nodes may not have the rest of their lymph nodes removed to check for more cancer. In these patients, radiation may be discussed as a treatment option after mastectomy.

If you were initially diagnosed with stage II breast cancer and were given treatment such as chemotherapy or hormone therapy before surgery, radiation therapy might be recommended if cancer is found in the lymph nodes at the time of the mastectomy. A doctor who specializes in radiation, called a radiation oncologist, may review your case to discuss whether radiation would be helpful to you.

If chemotherapy is also needed after surgery, the radiation is delayed until the chemo is done.

In some cases, breast reconstruction can be done during the surgery to remove the cancer. But if you will need radiation after surgery, it is better to wait to get reconstruction until after the radiation is complete.

Neoadjuvant and adjuvant systemic therapy (chemo and other drugs)

Systemic therapy is recommended for some women with stage II breast cancer. Some systemic therapies are given before surgery (neoadjuvant therapy), and others are given after surgery (adjuvant therapy). Neoadjuvant treatments are often a good option for women with large tumors, because they can shrink the tumor before surgery, possibly enough to make BCS an option. But this doesn’t improve survival more than getting these treatments after surgery. In some cases, systemic therapy will be started before surgery and then continued after surgery.

To help decide which women with stage II hormone receptor-positive, Her2-negative breast cancer will benefit from chemotherapy, a gene panel test such as Oncotype DX may be done on the tumor sample.

The drugs used will depend on the woman’s age, as well as tumor test results, including hormone-receptor status and HER2 status. Treatment may include:

  • Chemotherapy: Chemo can be given before or after surgery.
  • HER2 targeted drugs: For people with HER2-positive cancers, some will be treated with adjuvant (after surgery) chemotherapy with trastuzumab with or without pertuzumab for up to 1 year. Many women with HER2-positive cancers will be treated first with trastuzumab (with or without pertuzumab) followed by surgery and then more trastuzumab (with or without pertuzumab) for up to a year. If after neoadjuvant therapy, there is any residual cancer found at the time of surgery, the trastuzumab may be changed to a different drug, called ado-trastuzumab emtansine, which is given every 3 weeks for 13 doses. For people with cancer that is hormone receptor-positive, found in the lymph nodes, and have completed 1 year of trastuzumab, your doctor might also recommend additional treatment with an oral drug called neratinib for 1 year.
  • Hormone therapy: If the cancer is hormone receptor-positive, hormone therapy (tamoxifen, an aromatase inhibitor, or one followed by the other) is typically used. It can be started before surgery, but because it continues for at least 5 years, it needs to be given after surgery as well.

Treating stage III breast cancer

In stage III breast cancer, the tumor is large (more than 5 cm or about 2 inches across) or growing into nearby tissues (the skin over the breast or the muscle underneath), or the cancer has spread to many nearby lymph nodes.

If you have inflammatory breast cancer: Stage III cancers also include some inflammatory breast cancers that have not spread beyond nearby lymph nodes. Treatment of these cancers can be slightly different from the treatment of other stage III breast cancers. You can find more details in our section about treatment for inflammatory breast cancer.

There are two main approaches to treating stage III breast cancer:

Starting with neoadjuvant therapy

Most often, these cancers are treated with neoadjuvant chemotherapy (before surgery). For HER2-positive tumors, the targeted drug trastuzumab (Herceptin) is given as well, sometimes along with pertuzumab (Perjeta). This may shrink the tumor enough for a woman to have breast-conserving surgery (BCS). If the tumor doesn’t shrink enough, a mastectomy is done. Nearby lymph nodes will also need to be checked. A sentinel lymph node biopsy (SLNB) is often not an option for stage III cancers, so an axillary lymph node dissection (ALND) is usually done.

Often, radiation therapy is needed after surgery. If breast reconstruction is done, it is usually delayed until after radiation is complete. In some cases, additional chemo is given after surgery as well.

After surgery, some women with HER2-positive cancers will be treated with trastuzumab (with or without pertuzumab) for up to a year. Many women with HER2-positive cancers will be treated first with trastuzumab (with or without pertuzumab) followed by surgery and then more trastuzumab (with or without pertuzumab) for up to a year. If after neoadjuvant therapy, any residual cancer is found at the time of surgery, trastuzumab may be changed to a different drug, called ado-trastuzumab emtansine, which is given every 3 weeks for 13 doses. For people with hormone receptor-positive cancer in the lymph nodes who have completed a year of trastuzumab, the doctor might also recommend additional treatment with an oral drug called neratinib for a year.

Women with hormone receptor-positive (ER-positive or PR-positive) breast cancers will also get adjuvant hormone therapy which can typically be taken at the same time as trastuzumab.

Starting with surgery

Another option for stage III cancers is treatment with surgery first. Because these tumors are fairly large and/or have grown into nearby tissues, this usually means getting a mastectomy. For women with fairly large breasts, BCS may be an option if the cancer hasn’t grown into nearby tissues. SLNB may be an option for some patients, but most will need an ALND. Surgery is usually followed by adjuvant chemotherapy, and/or hormone therapy, and/or HER2-positive treatment (trastuzumab, pertuzumab, or neratinib). Radiation is recommended after surgery.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

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Last Medical Review: September 18, 2019 Last Revised: September 18, 2019

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