Breast Cancer

What is breast cancer?

Breast cancer is the abnormal growth of cells in the breast. These cells grow and develop into a cancerous growth that can have the potential to spread to other parts of the body.

Breast cancer is the most common cancer among Singaporean women. 1

More than 25% of all cancers diagnosed in women are breast cancers. Between 2011 and 2015, about 1 927 women were diagnosed with breast cancer in Singapore each year.2

Risk factors associated with breast cancer

There is no single cause of breast cancer, however there are a number of risk factors that can increase your chance of developing breast cancer including genetic, lifestyle and environmental factors.

These can include:

  • Gender – being female increases your risk
  • Having a family history of, or close relative who has had, breast cancer
  • Aging – women who are 50-years-old are 10 times more at risk to develop breast cancer than women who are 30-years-old 11
  • Drinking alcohol 11
  • Being overweight

Is breast cancer hereditary?

In 5-10% of cases, breast cancer is hereditary. The cancer is caused by specific gene mutations (changes) in the BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two) genes.2 There are several other genes other than BRCA1 and BRCA2 that also help make up this percentage.

These genes can develop abnormally which may then be passed down through family generations, increasing the chance of breast (and ovarian) cancers.2

Signs and symptoms of breast cancer

Breast tissue often feels lumpy, so it can be difficult to know the difference between what is normal and what could be a cancerous lump.

Some common symptoms of breast cancer to keep an eye out for include: 5

Changes

in the size or shape of your breast

Any new lumps

in the breast or under your arm

Discharge of fluid

(except breast milk) from the nipple, including blood

Dimpling or a ‘pulling’

of skin on your breast

Breast pain or swelling

Dry, flaky red skin

around the nipple area

Knowing your breasts is extremely important to help you detect any potential signs of breast cancer.6

You can do this by performing a routine self-examination each month.

How is breast cancer diagnosed?

Following consultation and physical examination by your doctor, you may receive a number of tests to assist in diagnosing breast cancer. This may include a:

  • Mammogram
  • MRI scan
  • Ultrasound
  • Biopsy

Stages of breast cancer

Breast cancer is typically classified into stages from 0 – IV based on:

  • tumour size (T)
  • if the cancer has involved any lymph nodes (N)
  • whether the cancer has metastasised (spread) to other parts of the body (M).3

Types of breast cancer

There are many different types of breast cancer, some of which are common, while others are very rare. Some of these include:

  • Invasive ductal carcinoma (IDC) – IDC is the most common type of breast cancer. Invasive means that the cancer has begun to invade breast tissue close to where it originated. In the case of IDC, the cancer began in the milk duct and has now spread through the duct wall to other breast tissue.
  • Invasive lobular carcinoma (ILC) – Rather than beginning in the milk duct, ILC originates in the milk glands (known as lobules) and invades nearby areas of the breast.
  • Inflammatory breast cancer (IBC) – Unlike other types of breast cancer, IBC does not involve a lump in the breast. Instead, the skin of the breast may become red, inflamed, thick or pitted (like an orange), your nipple may become inverted, and the breast may become swollen, hard, tender and painful, or itchy. IBC is a rare type of breast cancer and is more likely to be advanced upon diagnosis, as it is difficult to identify using a mammogram.

Following a breast cancer diagnosis, further testing is then conducted to identify the receptor status of the cancer. Cancers will be classified as hormone receptor positive or negative depending on whether they have proteins that are oestrogen or progesterone receptors. Your breast cancer may be classified as ER+ (has oestrogen receptors), PR+ (has progesterone receptors), HR+ (has one or both of these receptors) or HR- (has neither of these receptors). Your cancer may also be classified as HER2 positive or negative. HER2 is a protein which promotes the growth of cancer cells and in HER2 positive breast cancer, there are higher than normal levels of HER2.

  • HR positive HER2 negative breast cancer – This is the most common form of breast cancer. A HR+ HER2- classification means the cancer has oestrogen or progesterone receptors but does not overexpress the gene HER2. It is typically treated using hormone therapies.
  • HER2 positive breast cancer – 25% of all breast cancers are HER2-positive, which is more common in women below the age of 60. HER2 positive breast cancer often spreads faster than other breast cancers, but responds well to treatments that target the HER2 protein (known as targeted therapies).
  • Triple negative breast cancer – Triple negative breast cancer accounts for 15% of all breast cancer cases and is an invasive breast cancer. It is classified as triple negative because it does not have the three proteins that are typically found on breast cancer cells: oestrogen, progesterone and HER2 receptors. It is more common in women younger than 40 or who have the BRCA1 gene mutation.

Treatment

Frequently asked questions

Does hormone replacement therapy (HRT) increase the risk of breast cancer?

There is convincing evidence that combined (oestrogen-progesterone) replacement therapy increases the risk of breast cancer.11

Risk increases the longer that HRT is used, and is higher in women who start replacement therapy close to menopause.11

What can I do to decrease my breast cancer risk?

There are several lifestyle factors you can control to help reduce your risk of developing breast cancer, including:

  • Getting regular exercise – At least 30 minutes of moderate-intensity exercise each day12
  • Eating a healthy, balanced diet – Eat a fibre-rich diet from grain and legume sources, as well as enjoy a variety of fruit (2 serves) and vegetables (5 serves) per day, limit your intake of salt, saturated fats, and avoid all processed meat13
  • Reducing alcohol intake – If you choose to drink, limit your alcohol intake to no more than two standard drinks a day. 11
  • Maintaining a healthy weight – Maintain a healthy weight within the normal BMI (Body Mass Index)* range of 18.5 – 24.9kg/m2.14

*To calculate your BMI = (weight (kg))/(height(m))2

Where can I find out more information about breast cancer?

The Breast Cancer Foundation can provide you with more information about the different stages of breast cancer.

How common is breast cancer in men?

Breast cancer in men is rare and only makes up approximately 1% of all breast cancer cases.

Like women, there are a number of factors that can increase male breast cancer risk. These include: 20

  • Age – the average age of breast cancer diagnosis is 69 years
  • Family history of breast cancer, or a known BRCA gene mutation
  • Hormonal imbalances – such as increased levels of oestrogens
  • Previous radiotherapy treatment

For more information, click here.

References

For a full list of references, click here.
  1. Breast cancer. (2019). Health Hub. Retrieved on 29 May 2019
  2. Breast Cancer – What it is. (n.d). Sing Health. Retrieved on 29 May 2019
  3. Stages, types and treatment of breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 18 December 2018
  4. Breast Cancer Stages. (2017). American Cancer Society. Retrieved on 19 December 2018
  5. What are the symptoms of breast cancer. (2018). Centre for Disease Control and Prevention (CDC). Retrieved on 18 December 2018
  6. Breast Self Examination. (n.d). Breast Cancer Foundation. Retrieved on 30 May 2019
  7. Surgery for breast cancer. (2016). American Cancer Society. Retrieved on 18 December 2018
  8. Radiation for breast cancer. (2017). American Cancer Society. Retrieved on 18 December 2018
  9. Chemotherapy for breast cancer. (2017). American Cancer Society. Retrieved on 18th December 2018
  10. Hormone therapy for breast cancer. (2017). American Cancer Society. Retrieved on 18 December 2018
  11. Risk factors for breast cancer: A review of the Evidence. (2018). Cancer Australia. Retrieved on 18 December 2018 
  12. Physical Activity and sedentary behaviour. (n.d). Cancer Australia. Australian Government. Retrieved on 18 December 2018
  13. (n.d) Cancer Australia. Australian Government. Retrieved on 18 December 2018
  14. Overweight and obesity. (n.d). Cancer Australia. Australian Government. Retrieved on 18 December 2018
  15. Stage 0 – pre-breast cancer. (n.d) National Breast Cancer Foundation. Retrieved on 13 January 2019 
  16. Stage 1 or 2 – Early breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 13 January 2019
  17. Stage 2 or 3 – Locally advanced breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 13 January 2019
  18. Stage 4 – Metastatic breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 13 January 2019 
  19. Targeted Therapies. (n.d). Icon Cancer Centre. Retrieved on 13 January 2019
  20. Men get breast cancer too. (2016). Breast Cancer Network Australia (BCNA). Retrieved on 14 January 2019 

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