Breast cancer can affect the body in various ways, including physical and emotional changes. It can cause tiredness, swelling, and changes to the skin and hair. It can also affect other parts of the body.

Breast cancer is a serious disease in which abnormal breast cells divide and grow uncontrollably.

According to the American Cancer Society, breast cancer is the most common cancer in females in the United States, except for skin cancers. Approximately 1 in 8 females will receive a diagnosis of breast cancer in their lifetime.

About 1 in 100 breast cancer diagnoses occur in males, reports the Centers for Disease Control and Prevention (CDC).

Early symptoms of breast cancer can vary from person to person, but some common symptoms include a lump in the breast and changes in breast shape or size.

This article provides an overview of the effects of breast cancer on the body and what to expect after a diagnosis.

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The most common symptom of breast cancer is a lump or mass in the breast. The lump is usually painless and irregular but can also be round and tender.

Other breast changes include:

  • swelling or thickening of the breast or underarm area
  • changes in the size or shape of the breast
  • nipple changes, such as the nipple turning inward or discharge
  • skin changes, such as inflammation, dimpling, or puckering

Not all breast changes are cancerous. Some breast changes may be due to benign conditions, such as fibrocystic breast disease or mastitis, which is an infection. These conditions can also cause lumps, swelling, and changes in the breast.

Learn more about how breast cancer can affect the breasts here.

Fatigue is a common symptom of breast cancer and its treatment. People may describe it as extreme tiredness or exhaustion that does not go away with rest.

The United Kingdom’s Cancer Research UK notes that cancer-related fatigue can occur due to:

  • The body’s immune response to cancer cells: The body’s immune system releases cytokines that can cause fatigue.
  • The energy demands of cancer cells growing and multiplying: Cancer cells require a lot of energy to grow and multiply, leaving the body tired.
  • The side effects of cancer treatments: Chemotherapy, radiation therapy, and surgery can all cause fatigue.
  • The emotional and psychological toll of living with a cancer diagnosis: The stress and anxiety of a cancer diagnosis can also contribute to fatigue.

Fatigue can vary from person to person. Some people may feel tired all the time. Others may only feel tired after doing certain activities.

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Learn more about breast cancer and tiredness:

Lymphedema is swelling caused by fluid buildup in the body’s tissues. It can occur after breast cancer treatment, such as surgery or radiation therapy, to the lymph nodes under the arm.

The swelling can be mild or severe and affect the:

  • arm
  • hand
  • breast
  • chest
  • shoulder
  • area on the back behind the armpit

While some swelling may improve on its own, swelling does not always go away. A person can speak with their cancer healthcare team for assessment and management.

Lymphedema may cause discomfort, heaviness, or tightness in the affected area. It may also cause limited range of motion and difficulty performing daily activities.

Breast cancer treatment can sometimes cause hair loss and skin changes.

The American Cancer Society states hair loss most commonly begins within 1–3 weeks of treatment. It becomes more noticeable after 1–2 months after beginning therapy.

Hair loss can occur for all body hair, including hair on the scalp, eyebrows, and eyelashes. It is usually temporary and begins to grow back after completing treatment. However, some people may experience permanent hair loss.

Skin changes can include:

  • rash
  • dimpling
  • puckering
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Learn more about how chemotherapy can affect the hair and skin:

Some cancer treatments, such as chemotherapy and radiation therapy, can damage the cells in the bone marrow. The bone marrow produces white blood cells.

White blood cells are important for fighting infections. A low white blood cell count can increase the risk of infection.

In addition, breast cancer can spread to the lymph nodes, which are part of the immune system. This can also weaken the immune system and make it more difficult to fight infections.

If a person notices any signs of infection during chemotherapy, such as a fever, they should contact a doctor immediately.

Breast cancer and its treatments can significantly affect a person’s sex life and fertility. The effects vary depending on the:

  • type of breast cancer
  • cancer stage
  • type of treatment
  • person’s age and overall health

Sex and fertility changes may include:

Breast cancer can have a wide range of effects on the body, from the skeletal and muscular systems to the nervous system. Breast cancer can cause pain, restricted movement, decreased muscle strength, and bone loss.

Not everyone experiences all of these effects. Their severity also varies from person to person.

Early diagnosis and treatment are important for managing the effects of breast cancer on the body.