Breast cancer

Breast cancer
Last update: 12-09-2023

How else can it be called?

  • Breast carcinoma

  • Neoplasm of the breast

  • ICD-10: C50

What is breast cancer?

A breast cancer is a rapid and uncontrolled growth of abnormal cells in the breast tissue.

The mammary gland comprises multiple clusters of lobes and lobules interconnected by thin ducts, resembling the branches of a tree. The most common type of breast cancer is ductal carcinoma, that develops in these ducts. The other type of breast cancer is lobular carcinoma.

While breast cancer can affect both women and men, over 99% of cases are diagnosed in women.

Breast cancer stands as the most prevalent cancer among women. It is estimated that 1 in every 8 women will have breast cancer at some point in their life.

Which are the causes of breast cancer?

While the exact causes of breast cancer remain not fully understood, several risk factors have been identified:

  • Age is the primary risk factor, especially in women over 50 years of age.
  • First-degree family history of breast cancer, such as a mother, sister, or daughter.
  • Genetic factors (mutations in the BRCA1 and BRCA2 genes). The risk increases up to 50 to 85% for developing breast cancer.
  • Personal history. A breast cancer in one breast increases the risk of developing cancer in the other breast.
  • History of atypical ductal hyperplasia.
  • Dense breast tissue in a mammogram.
  • Reproductive factors such as early onset of first menstruation, late menopause, and nulliparity (never having been pregnant).
  • Use of postmenopausal hormone replacement therapy.
  • Exposure to ionizing radiation during development or growth stages.
  • Lifestyle-related factors: obesity, alcohol and smoking.

How can it be detected?

The most effective way to prevent breast cancer is early detection and therefore periodic breast self-exam is essential.

If breast cancer is suspected through physical examination, additional studies should be conducted, such as:

  • Mammography: The use of X-rays to take images of the breast can detect abnormal areas.
  • Ultrasound: An ultrasound study produces images where it is possible to discern between cystic and solid masses that may be due to a cancer. This study complements mammography.
  • Magnetic Resonance Imaging (MRI): It uses an electromagnetic field to get the images. It is a test often necessary for women with dense breast tissue, BRCA gene mutations, or silicone breast implants.
  • Biopsy: It is used to confirm a breast cancer. A sample of breast tissue is analyzed under a microscope. A biopsy can be performed manually by palpation or under imaging guidance. The tissue can be obtained using a fine needle aspiration, a wider coring needle, or through an open surgical incision.

There are other types of procedures that may help detect the spread of cancer to other organs, such as:

  • Chest X-ray.
  • Abdominal ultrasound.
  • Bone scan (bone scintigraphy).
  • Computed Tomography (CT).
  • Positron Emission Tomography (PET).

Which are the stages of breast cancer?

The stages of breast cancer can be classified as follows:

  • Stage 0 breast cancer (carcinoma in situ)

    Cancer cells are confined to either the ductal or lobular tissue of the breast. Lobular carcinoma in situ, although not considered a true cancer, indicates a predisposition to develop it. Ductal carcinoma in situ is considered a type of cancer.

  • Stage I

    The tumor in the breast is 2 centimeters (cm) or smaller and has not spread to tissues outside the breast.

  • Stage II

    The tumor in the breast is 2 centimeters (cm) or smaller and has spread to axillary lymph nodes.

    The tumor is larger than 2 cm but 5 cm or smaller with or without axillary lymph node involvement.

    The tumor is larger than 5 cm but has not affected axillary lymph nodes.

  • Stage III

    • Stage III A

      The tumor is smaller than 5 cm but has spread to axillary lymph nodes, which are matted together or attached to other structures. It may also be larger than 5 cm with axillary spread.

    • Stage III B

      The tumor has spread to nearby tissues, such as the skin, ribs, chest muscles, or the lymph nodes of the chest wall.

    • Stage III C

      A tumor of any size that has affected more than 10 axillary lymph nodes, to lymph nodes behind the breastbone, and lymph nodes above or below the collarbone.

  • Stage IV

    The tumor has spread to other parts of the body (bones, lungs, liver, or brain) and may also involve the skin and lymph nodes of the neck and collarbone.

  • Inflammatory breast cancer

    It is a rare and very aggressive type of cancer. The breast often looks swollen and red and may feel warm. It progresses rapidly.

  • Recurrent

    The cancer has been previously treated, but cancer cells come back in the breast, chest wall, or in another part of the body.

What is the recommend treatment?

In the treatment of breast cancer, four types of treatment are used:

  • Surgery
  • Radiation therapy
  • Chemotherapy
  • Hormone therapy

Besides, ongoing clinical trials are exploring the use of biological therapy and bone marrow transplantation.

  1. Types of surgery for breast cancer
    • Breast-conserving surgery
      • Lumpectomy (excisional biopsy or wide excision): It is the removal of the tumor and a safety margin around it, and sometimes some axillary lymph nodes. It is often combined with radiation therapy.
      • Partial mastectomy: It is the removal of cancer with some surrounding tissue and the lining of the chest muscles beneath the tumor, along with axillary lymph nodes. Radiation therapy is also applied later.
    • Aggressive surgery
      • Radical mastectomy: It is the removal of the entire breast and the lining of the chest muscles and chest wall beneath the tumor, along with axillary lymph nodes. In a “modified radical mastectomy” some of the chest wall muscles are preserved.
  2. Radiation therapy can be external or delivered by insertion of radiation sources directly into the tumor (interstitial radiotherapy).
  3. Chemotherapy is administered intravenously.
  4. Hormone therapy is administered if the cancer cells have receptors for estrogen or progesterone. Tamoxifen is used as hormone therapy. It is given for 5 years in breast cancer without lymph node involvement. The issue is that it increases the risk of uterine cancer.

What is the recommend treatment based on the stage?

Depending on the stage of breast cancer, the treatment is:

Stage 0 breast cancer (Carcinoma In situ): The recommended treatment is breast-conserving surgery (tumorectomy) followed by hormonal therapy post-surgery. Another option is a simple mastectomy.

Stages I to III: Breast-conserving surgery or simple mastectomy is performed, followed by post-surgery radiation therapy. Other options that can be employed in combination include chemotherapy, hormonal therapy, and pharmacotherapy.

Stage IV: Mainly, systemic therapy is administered, including hormonal therapy, targeted therapy, or chemotherapy. Surgery and radiation therapy are only considered for preventing or treating specific symptoms.

Inflammatory breast cancer: The same guidelines as for stage III breast cancer are used.


  1. Hormonal therapy with or without surgery to remove the ovaries.
  2. If the recurrent tumor is isolated, surgery and/or radiation therapy are applied.
  3. Palliative radiation for pain management.
  4. Chemotherapy.
Medically reviewed by Jorge Herradora Pérez Ph.D. on 12-09-2023


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