What Age Does Breast Cancer Usually Start?

Medically Reviewed on 2/2/2022
breast cancer symptoms
Breast cancer is most often diagnosed in women older than 45 years of age (about 80 percent of all cases).

It is not known when exactly the cancer cells develop in the breast, but it is most often diagnosed in women older than 45 years (almost 80 percent of all breast cancer cases). Although breast cancer can affect anyone, less than five percent of breast cancer cases are seen in women younger than 40 years.

Several factors influence the risk of developing breast cancer. Age is one of the most significant of those factors.

What is breast cancer?

Abnormal and uncontrolled growth of the cells starting in the breast tissue is called breast cancer.

According to the American Cancer Society, one in every eight females in the United States will eventually develop breast cancer.

A breast is made up of three parts:

  1. Lobules: Milk-producing glands.
  2. Ducts: Tubes to carry milk to the nipple.
  3. Connective tissue (fibrous and fatty tissues): Supporting tissue that maintains the structure of the breast.

Most often, breast cancer begins in the lobules or ducts and may metastasize (spreads to other organs) through blood and lymph vessels.

Two common types of breast cancer

  1. Invasive ductal carcinoma: Cancer begins in the ducts and spreads to other breast tissues and parts of the body.
  2. Invasive lobular carcinoma: Cancer begins in the lobules and spreads to other breast tissues and parts of the body.

Ductal carcinoma in situ is a condition preceding breast cancer, wherein the cancer cells are present only in the duct lining and have not spread to the other tissues.

5 less common types of breast cancer

  1. Triple-negative breast cancer: An aggressive type, cancer cells lack estrogen, progesterone receptors, and HER2 protein.
  2. Inflammatory breast cancer: Cancer cells block lymph vessels in the skin of the breast making it red, tender, and swollen.
  3. Paget’s disease: A rare type that initiates in ducts and spreads to the skin of the nipple and areola.
  4. Angiosarcoma: A rare type that starts in cells that line blood vessels or lymph vessels.
  5. Phyllodes tumor: Cancer develops in the connective tissue (stroma) of the breast.

8 symptoms of breast cancer

Some warning signs of breast cancer include:

  1. A lump in the breast or armpit
  2. Swelling in the breast
  3. Dimpling or flaking of the skin of the nipple
  4. Redness and irritation of the skin
  5. Pain in the nipple area or the entire breast
  6. Change in the size or shape of the breast
  7. Watery or bloody discharge from the nipple
  8. Orange peel appearance of the breast skin

The look and feel of a normal breast are affected by menses, pregnancy, and childbirth, weight loss or gain, breastfeeding, and certain medications. If one is concerned about the changes in their breasts, they should consult a doctor.

Other conditions that may cause a lumpy or uneven breast:

  • Fibrocystic breast (benign growths in the breast)
  • Cysts (tiny fluid-filled sacs)

What are the risk factors of breast cancer?

Risk factors for breast cancer are either modifiable or unmodifiable, and may include the following:


  • Age: The risk of breast cancer increases with old age.
  • Family history: Higher risk for women who have a mother, sister, or a first-degree relative diagnosed with breast cancer.
  • Genes: Inherited mutations to BRCA1 and BRCA2 genes make a woman more vulnerable.
  • Previous medical history: Women who have had breast cancer removed or treated previously are more prone to develop it the second time.
  • Reproductive history: Early menarche (before 12 years) and late menopause (after 55 years) raises the risk of breast cancer due to longer hormonal exposure.
  • Dense breasts: Women with dense breasts have a higher risk.
  • History of radiation therapy: Radiation exposure before age of 30 years raises the risk of breast cancer in later life.


  • Overweight or obesity: Women with a higher body mass index are at a greater risk.
  • Physically inactive: A sedentary lifestyle makes a woman more vulnerable.
  • Obstetric history: First pregnancy after the age of 30 years and no breastfeeding raises the risk.
  • Alcohol: Alcohol consumption can increase the risk of breast cancer.
  • Hormonal therapy: Certain oral contraceptive pills and hormone replacement therapy for menopause raises the risk, especially when taken for more than five years.
  • Smoking: Smokers have a higher risk than nonsmokers.


Breast Cancer Awareness: Symptoms, Diagnosis, and Treatment See Slideshow

How is breast cancer diagnosed?

The United States Preventive Services Task Force recommends women aged 50 to 74 years and who are at risk of breast cancer should go for a mammogram every two years.

Women aged between 40 and 49 years must discuss with their doctor when to start going for a mammogram and how often.

  • Self-awareness: Being aware of the feel of a normal breast, a regular self-examination to look for any change in the size or shape or presence of a new lump are all part of self-awareness.
  • Clinical breast examination: An examination done by a doctor to feel for any changes or lumps in the breast.
  • Mammogram: An X-ray of the breast is used to diagnose changes in breast tissues and early signs of breast cancer. Mammograms can detect a lump or an abnormal growth suspicious of cancer about two years before it can be palpated.
    • Screening mammogram: A routine screening procedure in females without any symptoms.
    • Diagnostic mammogram: More detailed images of the breast are taken of females presenting with symptoms.
  • Breast magnetic resonance imaging: Magnetic fields and X-rays are used to take images of the breast tissue.
  • Breast ultrasound: Breast tissue images are taken by using special sound waves.
  • Biopsy: A tissue sample is taken and examined under a microscope.

4 stages of breast cancer

After breast cancer diagnosis, other tests are done to evaluate the extent of spread by a process called “staging.”

  1. Stage 0: Cancer cells are localized to milk ducts.
  2. Stage I: Tumor is smaller than 2 cm, with no other structure involvement.
  3. Stage II:
    • Stage IIA: Tumor less than 2 cm, spread to lymph nodes of the armpit or 
      • tumor ranges from 2 to 5 cm, with or without spread to lymph nodes.
    • Stage IIB: Tumor is larger than 5 cm with lymph node involvement.
  4. Stage III:
    • Stage 3A: Cancerous lymph nodes adheres to the surrounding tissues.
    • Stage 3B: Tumor has spread to near structures, such as chest wall.
  5. Stage IV: Tumor has spread to distant structures, such as the lungs, liver, or brain.

5 treatment options for breast cancer

According to the American Cancer Society, early-stage (localized) breast cancer has a five-year survival rate of about 99 percent.

  1. Surgery: The cancerous tissues are surgically removed.
  2. Chemotherapy: Medications to kill or restrict the growth of the cancerous cells.
  3. Biological therapy: Immune system of the body is encouraged to fight cancerous tissues.
  4. Hormonal therapy: Works by blocking the hormones necessary for the growth of cancer cells.
  5. Radiation therapy: High energy rays are used to kill cancer cells.

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Medically Reviewed on 2/2/2022
Image Source: iStock Images

Centers for Disease Control and Prevention. Breast Cancer. https://www.cdc.gov/cancer/breast/basic_info/what-is-breast-cancer.htm

American Cancer Society. What is breast cancer. https://www.cancer.org/cancer/breast-cancer/about/what-is-breast-cancer.html

Cleveland Clinic. Breast Cancer. https://my.clevelandclinic.org/health/diseases/3986-breast-cancer