Breast Cancer

Medically reviewed by NCIS Specialists. Last reviewed by Adj Associate Prof Samuel Ow. Published on 8 Sep 2026.

Breast cancer occurs when cells in the breast grow abnormally. It may not cause any pain or symptoms early on, making it difficult to detect. Breast cancer affects one in 13 women, but when caught early, more than 90 per cent survive. This is why breast cancer screening matters, as early detection leads to more effective treatment and better patient outcomes.

What is breast cancer?

When breast cells divide and grow without control, breast cancer occurs. Breast cancer, when detected early, can be treated readily and has a very good chance for cure.

The female breast is made up mainly of:

• Ducts (tiny tubes that carry the milk from the lobules to the nipple)
• Lobules (milk-producing glands)
• Stroma (fatty tissue and connective tissue surrounding the ducts and lobules, blood vessels, and lymphatic vessels)

Breast cancer that is confined to the ducts (Ductal Carcinoma In-Situ) is non-invasive. Cancer that spreads beyond the ducts or lobules to the surrounding breast tissue enters the invasive stage. Over time, breast cancer in the invasive stage can spread to the lymph nodes and possibly to other areas of the body.

What are the signs & symptoms of breast cancer?

Lumps in your breast, swelling, and redness are the most common signs and symptoms of breast cancer.

Symptoms include: 

• A lump or thickening in or near the breast or in the underarm area
• Blood or unusual nipple discharge
• Change in the size or shape of the breast
• Dimpling or puckering of skin overlying the breast
• Itchy rash on the nipple
• Nipple retraction
  
• Scaly, red or swollen skin on breast, nipple or areola

Please speak to your doctor if you notice any of the above symptoms.

What are the risk factors related to breast cancer?

There are several risk factors related to breast cancer:

• A personal history of breast cancer or certain benign (non-cancer) breast disease
• Early onset of menstruation and late menopause
  
• Excessive alcohol intake
• Family history of breast cancer
• Female gender
  
• Having no children or having the first child at an older age
• Long term hormone replacement therapy
• Obesity
• Previous exposure to radiation therapy to the chest during childhood or as a young adult

How is breast cancer diagnosed?

Breast cancer is detected through:

• Mammography
  A low-dose X-ray of the breast that can detect small lumps or abnormalities before they can be felt. It is the most common screening tool for breast cancer.
  
  
• Breast Ultrasound
  Uses sound waves to create images of breast tissue. It is often used to determine whether a lump is solid (potentially cancerous) or fluid-filled (likely a benign cyst).
  
  
• Breast MRI (Magnetic Resonance Imaging)
  Uses strong magnets and radio waves to create detailed breast images. This is recommended for high-risk individuals or for further evaluation of suspicious findings from mammograms or ultrasounds.
  
  
• Clinical Breast Examination (CBE)
  A physical exam performed by a doctor to check for lumps, skin changes, or abnormalities in the breast and underarm area.
  
  
• Breast Self-Examination (BSE)
  A self-check performed at home to look for lumps, skin dimpling, or changes in breast shape and size. While not a reliable standalone screening tool, it helps individuals stay aware of any unusual changes.
  

What are the different types of breast cancer?

Breast cancer is not just one disease. It has different subtypes that affect treatment and outcomes. Knowing the subtype helps doctors choose the best treatment plan.

Hormone Receptor-Positive (HR+)

• The most common subtype
• Cancer cells have receptors for oestrogen and/or progesterone, which help them grow
• Treatments often include hormone (endocrine) therapy to block or lower hormone levels in the body
  

HER2-Positive (HER2+)

• Cancer cells produce too much of the HER2 protein, which promotes tumour growth
• Targeted therapies (also known as Anti-HER2 therapies) are available to specifically block the HER2 protein, and are given in combination with chemotherapy
  

Triple-Negative Breast Cancer (TNBC)

• Makes up about 10-15% of cases
• Lacks estrogen, progesterone, or HER2 receptors
• May be more receptive to chemotherapy, and in some cases, immunotherapy

What are the treatment options for breast cancer?

Treatment for breast cancer depends on how advanced the cancer stage is. Your care team will recommend a personalised treatment plan based on your condition.

Understanding the stages

[Stage 0] Non-invasive breast cancer 
The cancer is contained within the breast ducts and has not spread.

[Stage 1-3] Invasive breast cancer
The cancer has spread into the surrounding breast tissue and may affect nearby lymph nodes on the same side. The stage is more advanced if the tumour is larger, or the lymph nodes are affected by cancer.

[Stage 4] Metastatic breast cancer
The cancer that has spread to other organs of the body such as the lungs, liver, bones or brain

Common treatments

Surgery is often the main treatment for early-stage breast cancer:

• Lumpectomy (only the abnormal cells and surrounding tissue is removed)
• Mastectomy (entire breast is removed)
• Nearby lymph nodes may also be removed to check for spread

Radiation therapy

• Usually required after a lumpectomy
• Helps reduce the risk of the cancer returning in the remaining breast tissue
• Radiation is not always required after a mastectomy, but the doctor may discuss radiation therapy if the tumour was large or the lymph nodes were affected by cancer

Understanding the treatments related to different stages of breast cancer

[Stage 1] Early stage breast cancer

The cancer is relatively small and has not spread beyond the breast.

Surgery is required:

• Smaller tumours: Lumpectomy
• In other cases, a mastectomy will be performed
• Some of the lymph glands in the armpit (on the same side as the tumour) are also removed at the same time.
  

Radiation therapy is required after a wide excision. Women with Stage 1 cancer who undergo a mastectomy don't usually need radiation.

Chemotherapy is often used after surgery to lower the risk of recurrence, if required. Women who have larger tumours or affected lymph nodes are more likely to need it.

Hormone therapy is used after surgery in women who have hormone receptor-positive cancer (which is dependent on female hormones such as oestrogen for growth). Examples of hormone therapies include Tamoxifen and Letrozole.

[Stage 2] Cancer is still contained within the breast and (in some cases) in nearby lymph nodes.

• The treatment options are similar to the ones for Stage 1 Cancer.
• Sometimes, chemotherapy in this stage is used to shrink a tumour before surgery (neoadjuvant therapy). In HER2+ breast cancer, this is often combined with Anti-HER2 therapy. In triple negative breast cancer, this may be combined with immunotherapy. If the tumour shrinks significantly with neoadjuvant therapy, the breast surgeon may be able to offer lumpectomy instead of mastectomy in suitable cases.
• After surgery, radiation therapy may be offered. If Anti-HER2 therapy or immunotherapy was offered initially, treatment will be continued for a total of 1 year. Hormone therapy is also offered in women with hormone receptor-positive cancer.
  
  

[Stage 3] Cancer in the breast is larger, and has spread to involve more lymph nodes.

• Surgery, chemotherapy and radiation therapy are used to treat Stage 3 Breast Cancer. Neoadjuvant chemotherapy is typically offered by the doctor to shrink the tumour before surgery.
  
  

[Stage 4] Cancer has spread to other parts of the body

• As the cancer has spread beyond the breast and lymph nodes, surgery is typically no longer offered.
• The objective of treatment is to shrink the cancer to slow down the disease and prolong life.
• Drug therapy like hormone therapy, chemotherapy or targeted therapy is the main treatment here.
  
  

Surgical Options

Surgery is one of the main treatments for non-metastatic breast cancer. Depending on the size and position of the cancer and your preferences, the surgeon will recommend one or more of the following surgical options.

• Wide local excision: Removal of the cancer and some of the normal breast tissue around it
• Oncoplastic surgery (breast conserving surgery): Removal of the cancer with improved cosmetic outcomes, women can choose to have surgery on the unaffected breast to improve the symmetry
• Mastectomy: Removal of the whole breast
• Reconstructive surgery: Making a new breast shape using implants and /or own tissue
• Sentinel lymph node biopsy: Removal of 1 to 3 lymph nodes in the armpit to check for cancer cells
• Axillary lymph node dissection: Removal of 10 or more lymph nodes in the armpit

After breast cancer surgery, additional treatments such as radiation therapy, hormonal therapy, chemotherapy and/or biological therapy may be offered to reduce the risk of cancer recurrence.

Frequently Asked Questions