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Stage 1 Breast Cancer: Treatment and Prognosis

Posted on March 22, 2022
Medically reviewed by
Mark Levin, M.D.
Article written by
Aminah Wali, Ph.D.

Breast cancer is classified into different stages ranging from 0 to 4. Staging is based on the tumor’s size and whether tumor cells have spread to other parts of the body. Determining your cancer’s stage can help your doctor determine your prognosis and the best treatment options.

The TNM staging system — which stands for tumor, node, and metastasis — is generally used for breast cancer staging. The system stages tumors based on:

  • Tumor — How large is the primary tumor?
  • Node — Are there cancer cells in lymph nodes?
  • Metastasis — Has the cancer metastasized, or spread, to other parts of the body?

Each letter is assigned a number, often with a letter following it. A lower number corresponds to early stage breast cancer, and a higher number indicates more advanced breast cancer.

Other information is also used to better understand the stage of the cancer. This can include:

  • Hormone receptor status — Whether the cancer contains estrogen receptors or progesterone receptors, proteins that respond to hormones in the body
  • Tumor grade — A measure of how abnormal the cancer cells look compared to normal cells
  • HER2 status — Whether the cancer has high levels of a protein called HER2
  • Oncotype DX score — Results of a genetic test used to predict if a cancer might progress to a more serious form of cancer

Following breast cancer diagnosis, a doctor will determine the most effective treatment based on the cancer’s stage.

What Is Stage 1 Breast Cancer?

Invasive breast cancer occurs when cancer cells have started to move from their original location — usually in the milk ducts — into the surrounding breast tissue. Stage 1 breast cancer is the earliest form of invasive breast cancer. It may further be classified into substages: stage 1a and stage 1b.

Stage 1a Breast Cancer

Stage 1a breast cancer is characterized by a breast tumor measuring up to 2 centimeters with no cancer cells found outside the breast.

Stage 1b Breast Cancer

Stage 1b breast cancer can signify one of two possibilities:

  • There is no tumor in the breast. Instead, groups of cancer cells between 0.2 millimeter and 2 millimeters are found in the lymph nodes.
  • There is a tumor in the breast smaller than 2 centimeters. There are also groups of cancer cells between 0.2 millimeters and 2 millimeters found in the lymph nodes.

Treatments for Stage 1 Breast Cancer

Treatment options for stage 1 breast cancer typically include surgery to remove the affected tissue. Radiation and drug therapy may be used as adjuvant therapy — therapy that comes after surgery — to lower the chance of recurrence.

Surgery

A mastectomy is a surgical procedure that removes all breast tissue. Different types of mastectomies may be performed depending on how aggressive the cancer is. Stage 1 breast cancer is likely to be treated with a total mastectomy, which removes the breast but leaves nearby lymph nodes. A mastectomy is necessary for people with large breast tumors. Some people may choose to have reconstructive surgery following a mastectomy to restore the appearance of their breast or breasts.

An alternative to mastectomy is a partial mastectomy, also referred to as breast-conserving surgery or a lumpectomy. In this procedure, a surgeon removes the breast tumor and some of the surrounding tissue. This is often the preferred surgical option for people with small tumors that are more easily removed.

Following lumpectomy, radiation therapy is commonly used to kill off any remaining cancer cells that may have been missed.

Lymph Node Dissection

If the cancer cells have spread into the lymph nodes, such as in stage 1b cancer, a lymph node dissection (or biopsy) is generally needed to remove the affected tissue. An axillary lymph node biopsy to remove lymph nodes in the underarm that contain cancer cells may be performed after surgery.

A sentinel lymph node biopsy is a less invasive procedure that can remove affected lymph nodes — and possibly eliminate the need for surgery. In some cases, axillary lymph node biopsy may still be required.

Chemotherapy

Chemotherapy is a common cancer treatment that selectively eliminates tumor cells. While chemotherapy is typically used to kill cancer cells left behind after surgery, chemotherapy can be used to shrink the tumor before surgery in more advanced cases.

Hormonal Therapy

To consider hormonal therapies, a doctor will confirm the hormone receptor status of the cancer. Some breast cancers are positive for the estrogen receptor or progesterone receptor. These hormone receptors are proteins that play a role in breast cancer growth.

Hormone receptor-positive stage 1 breast cancers are typically eligible for treatment with tamoxifen or exemestane (Aromasin), though exemestane is only considered for postmenopausal women. These are hormonal therapy drugs that specifically target the hormone receptors. Hormonal treatment may lower the likelihood of the cancer returning after treatment.

Targeted Therapy

Targeted therapy drugs work by stopping the function of a particular protein or group of proteins. HER2 is a protein that is present at high levels in some breast cancers. It affects how the cancer grows. HER2-positive stage 1 cancers may be treated with drugs that specifically target the HER2 protein.

Immunotherapy

Breast cancer that is negative for estrogen receptors, progesterone receptors, and HER2 receptors is called triple-negative breast cancer. This type of breast cancer is particularly difficult to treat. Immunotherapy may be recommended as an additional treatment option. Immunotherapy drugs work by interacting with a person’s immune system so that it can recognize and fight the cancer cells.

Prognosis for Stage 1 Breast Cancer

Survival rates for breast cancer are determined based on whether the cancer is localized (only in the breast), regional (spread to nearby tissues), or distant (spread farther throughout the body).

Stage 1 breast cancer is localized and has a very favorable prognosis (outlook). Its five-year survival rate is at least 99 percent. Early diagnosis helps, as well as thorough tumor testing. This helps ensure that each person receives the right therapies for their cancer.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Have you or a loved one been diagnosed with stage 1 breast cancer? Share your experiences in the comments below, or start a conversation by posting on MyBCTeam.

All updates must be accompanied by text or a picture.
Mark Levin, M.D. is a hematology and oncology specialist with over 37 years of experience in internal medicine. Review provided by VeriMed Healthcare Network. Learn more about him here.
Aminah Wali, Ph.D. received her doctorate in genetics and molecular biology from the University of North Carolina at Chapel Hill. Learn more about her here.

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