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.

In 2018, more than 18,200 Australians were estimated to be diagnosed with breast cancer, with 99% of these cases estimated to be women.1

Fortunately, Australia has one of the best survival rates of breast cancer in the world, with five and ten year survival rates of 90% and 83% respectively.1

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 the proteins oestrogen or progesterone receptors on the surface. 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 – 15-20% 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.

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.1 There are several other genes other than BRCA1 and BRCA2  that also help make up this percentage.

The BRCA1 and BRCA2 genes are responsible for cell repair and growth, as well as healthy function of breast, ovarian and other body tissues.Sometimes, these genes develop mutations which can then be passed down through family generations, increasing the chance of a range of cancers including breast and ovarian.2

Stages of breast cancer

Breast cancer classification is complex, but it is typically classified into stages from 0 – IV based on:

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

Signs and symptoms of breast cancer

Breast tissue can typically feel lumpy, therefore it can be difficult to know what is normal and what could be a cancerous lump.

However, some common symptoms to look out for are: 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 one of the most important things you can do to help detect changes.6

You can do this by routine, monthly self-examinations.

Treatment for breast cancer

Frequently asked questions

What causes breast cancer?

There is no one cause of breast cancer, rather it is a combination of genetic, lifestyle and environmental factors that can increase your risk.

Risk factors include:

  • Being female
  • Having a family history of, or close relative who has had breast cancer
  • Aging – women who are aged 50 years have a 10 times increased risk of breast cancer compared to women who are 30 years.11
  • Drinking alcohol – there is an increased risk of breast cancer with each additional unit of alcohol consumed. 11
  • Being overweight
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 with the duration of HRT use, and it is higher in those women who start replacement therapy close to their menopause.11

What can I do to decrease my risk of breast cancer?

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

  • Get regular exercise – Cancer Australia recommends at least 30 minutes of moderate-intensity exercise each day12
  • Eat 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
  • Reduce alcohol intake – If you choose to drink, try to limit your alcohol intake to no more than two standard drinks a day. 11
  • Maintain a healthy weight – Cancer Australia recommends maintaining 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 staging?

The National Breast Cancer Foundation provides detailed information about the different stages of breast cancer.

How common is breast cancer in men?

Breast cancer in men is not that common, and only makes up approximately 1% of all breast cancer cases.

Like women, there are a number of factors that can increase the risk for breast cancer for men, including; 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, you can look at the Breast Cancer Network Australia’s booklet – ‘Men get breast cancer too’

References

For a full list of references, click here.
  1. Current Breast Cancer Statistics in Australia. (2018). Retrieved on 18th December 2018 from https://www.bcna.org.au/media/6101/bcna-2018-current-breast-cancer-statistics-in-australia-31jan2018.pdf
  2. Genetics. (n.d). BreastCancer.org. Retrieved on 18th December 2018 from https://www.breastcancer.org/risk/factors/genetics
  3. Stages, types and treatment of breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 18th December 2018 from https://nbcf.org.au/about-national-breast-cancer-foundation/about-breast-cancer/stages-types-treatment-breast-cancer/
  4. Breast Cancer Stages. (2017). American Cancer Society. Retrieved on 19th December 2018 from https://www.cancer.org/cancer/breast-cancer/understanding-a-breast-cancer-diagnosis/stages-of-breast-cancer.html
  5. What are the symptoms of breast cancer.(2018). Centre for Disease Control and Prevention (CDC). Retrieved on 18th December 2018 from https://www.cdc.gov/cancer/breast/basic_info/symptoms.htm
  6. Breast Self-Exam. (n.d). National Breast Cancer Foundation. Retrieved on 18th December 2018 from https://www.nationalbreastcancer.org/breast-self-exam
  7. Surgery for breast cancer. (2016). American Cancer Society. Retrieved on 18th December 2018 from https://www.cancer.org/cancer/breast-cancer/treatment/surgery-for-breast-cancer.html
  8. Radiation for breast cancer. (2017). American Cancer Society. Retrieved on 18th December 2018 from https://www.cancer.org/cancer/breast-cancer/treatment/radiation-for-breast-cancer.html
  9. Chemotherapy for breast cancer. (2017). American Cancer Society. Retrieved on 18th December 2018 from https://www.cancer.org/cancer/breast-cancer/treatment/chemotherapy-for-breast-cancer.html
  10. Hormone therapy for breast cancer. (2017). American Cancer Society. Retrieved on 18th December 2018 from https://www.cancer.org/cancer/breast-cancer/treatment/hormone-therapy-for-breast-cancer.html
  11. Cancer Australia. (2018) Risk factors for breast cancer: A review of the Evidence. Retrieved on 18th December 2018 from https://canceraustralia.gov.au/system/tdf/publications/risk-factors-breast-cancer-review-evidence-2018/pdf/rfbcr_risk_factors_for_breast_cancer_a_review_of_the_evidence_2018_report.pdf?file=1&type=node&id=6421
  12. Physical Activity and sedentary behaviour. (n.d). Cancer Australia. Australian Government. Retrieved on 18th December 2018 from https://canceraustralia.gov.au/publications-and-resources/position-statements/lifestyle-risk-factors-and-primary-prevention-cancer/lifestyle-risk-factors/physical-activity-and-sedentary-behaviour
  13. Diet. (n.d) Cancer Australia. Australian Government. Retrieved on 18th December 2018 from https://canceraustralia.gov.au/publications-and-resources/position-statements/lifestyle-risk-factors-and-primary-prevention-cancer/lifestyle-risk-factors/diet
  14. Overweight and obesity. (n.d). Cancer Australia. Australian Government. Retrieved on 18th December 2018 from https://canceraustralia.gov.au/publications-and-resources/position-statements/lifestyle-risk-factors-and-primary-prevention-cancer/lifestyle-risk-factors/overweight-and-obesity
  15. Stage 0 – pre-breast cancer. (n.d) National Breast Cancer Foundation. Retrieved on 13th January 2019 from //nbcf.org.au/18/stage0-pre-breast-cancer/
  16. Stage 1 or 2 – Early breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 13th January 2019 from https://nbcf.org.au/about-national-breast-cancer-foundation/about-breast-cancer/stages-types-treatment-breast-cancer/stage-1-2-early-breast-cancer/
  17. Stage 2 or 3 – Locally advanced breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 13th January 2019 from https://nbcf.org.au/about-national-breast-cancer-foundation/about-breast-cancer/stages-types-treatment-breast-cancer/stage-2-3-locally-advanced-breast-cancer/
  18. Stage 4 – Metastatic breast cancer. (n.d). National Breast Cancer Foundation. Retrieved on 13th January 2019 from https://nbcf.org.au/about-national-breast-cancer-foundation/about-breast-cancer/stages-types-treatment-breast-cancer/stage-4-metastatic-breast-cancer/
  19. Targeted Therapies. (n.d). ICON Cancer Centre. Retrieved on 13th January 2019 from https://iconcancercentre.com.au/treatment/targeted-therapies/
  20. Men get breast cancer too. (2016). Breast Cancer Network Australia (BCNA). Retrieved on 14th January 2019 from https://www.bcna.org.au/media/6467/men-get-breast-cancer-too-booklet-web.pdf?_ga=2.267601998.1909084069.1547442095-719496387.1547442095

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