Breast cancer | Mate pukupuku ūtaetae

Key points about breast cancer

  • Breast cancer can occur at any age but is most common in women between 50 and 70 years old. Your risk's greater if you have a family history of breast cancer.
  • Treatment is usually more successful if breast cancer is found at an early stage.
  • For this reason, women should have a free mammogram every 2 years from 45 to 69 years old and self-check their breasts regularly.
  • By the time you can feel a breast cancer, it's about the size of a cherry or walnut while mammograms can pick up breast cancers that are as small as a grain of rice.
  • If you find a breast lump, see your healthcare provider to have it checked.
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Breast cancer (mate pukupuku ūtaetae) is a harmful growth that starts in your breast tissue. It is the most common cancer among New Zealand women, affecting 1 in 9 women over their lifetime.

On average, 9 people in Aotearoa New Zealand, will hear the news today that they have breast cancer. 

Breastscreen Aotearoa(external link) is a national screening programme providing free mammograms to women aged 45 to 69 years, every 2 years. This service helps to catch breast cancer early and save lives. Read more about breast screening.

Men can develop breast cancer, though this is rarer, adding up to about 1% of all breast cancers.

Cancer is caused when some of the cells in our body start to grow out of control. These cells keep multiplying and form a lump called a tumour.

Some breast cancers grow very slowly, while others grow much faster. Breast cancer can spread to the lymph glands and to other parts of the body, such as the bones and liver.

The causes of breast cancer are not clear, but many risk factors are known. The main factors that influence your risk include being female and getting older. Most breast cancers are found in those who are 50 years old or older. Read more about risk factors for breast cancer below.

Breasts undergo changes throughout life. In particular, breasts may become sore, lumpy or swollen during the menstrual cycle. Not all breast lumps are caused by cancer, but some breast changes that may be early signs of cancer include:

  • a distinct lump or lumpiness
  • thickening of the tissue or skin
  • nipple changes, such as skin dimpling
  • a blood-stained discharge from one nipple
  • an inverted nipple (unless the nipple has always been turned in)
  • a rash on a nipple
  • a change in breast shape
  • a painful area
  • a rash or red mark that appears only on your breast.

If you have any of these changes. You don’t necessarily have breast cancer, but you should see your healthcare provider to get your breasts checked.

Most breast cancers begin in the milk ducts (ductal cancers), while a small number start in the milk sacs or lobules (lobular cancers). Within these 2 groups there are different subtypes of breast cancer.

The causes of breast cancer are not clear, but many risk factors are known. The following factors increase your chance of getting breast cancer:

  • Being female.
  • Getting older (for females).
  • Having previously had breast cancer.
  • having an increased number of abnormal cells in the milk ducts (atypical hyperplasia). This can be seen in a breast biopsy.
  • A family history of breast cancer:
    • This risk can be mild, moderate or high, and depends on the number of relatives affected, whether they are first or second-degree relatives (first-degree are sisters, brothers and parents), and the age of the relative(s) when their breast cancer was found.
  • People who have inherited one of the abnormal BRCA genes associated with breast cancer.

Even with a high risk, most people won't develop breast cancer. 

Heredity and breast cancer

About 1 in 20 breast cancers is caused by a faulty breast cancer gene. If yours was caused by such a gene, your doctor can help you decide whether genetic testing would be helpful for your wider family. Find out more about the BRCA gene.

Most women who develop breast cancer have no family history of the disease, so being aware of what to watch out for and having regular mammograms are your best protection.

Read more about breast cancer screening and mammograms.

You can't change your genes, but you can reduce your chance of getting breast cancer by:

  • exercising regularly
  • limiting alcohol
  • breastfeeding, if possible
  • talking to your healthcare provider about contraception or menopause treatments that don't use oestrogen.

Being overweight increases risk, and reducing weight reduces risk.

  • Be aware of what your breasts look and feel like normally (see video below). If you notice any changes see your healthcare provider.
  • Make use of the free breast screening programme in Aotearoa New Zealand. Every woman from 45 to 69 years of age is eligible for free mammograms every 2 years.  
  • Ask your healthcare provider whether you need extra screening. It will depend on how many of your relatives have (or had) breast cancer and how old they were when they got it. 

Video: Checked your breasts lately? We'll show you how.

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(Breast Cancer Foundation, NZ, 2015)

Breast cancer is diagnosed by a combination of:

  • physical examination of your breast tissue
  • diagnostic imaging such as mammogram and ultrasound
  • diagnostic tests such as biopsy and testing of cell samples.

Your healthcare provider will talk to you about your medical history and symptoms and will do a physical examination. They may arrange more tests or you may be referred directly to a specialist for a mammogram and/or ultrasound scan. 

Further testing may be required including taking a sample of cells from the lump, biopsy or removal of the lump, and laboratory testing on any breast tissue samples. 

Read more about breast cancer diagnosis.

Breast cancer is treated by 4 different methods: surgery, radiation treatment (radiotherapy), chemotherapy; and hormone treatment.

Which treatment or combination of treatments is used depends on the type and size of the breast cancer and whether it has spread, and the age, general health and personal choice of the woman with breast cancer.

Read more about breast cancer treatment.

Video series interviewing people about their personal journey with breast cancer including the signs, symptoms and treatment.

Video: Helena's story

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(Breast Cancer Foundation NZ, 2015)

Video: Kat's story

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(Breast Cancer Foundation NZ, 2011)

Watch more personal stories(external link)(external link) from the Breast Cancer Foundation NZ.

Video: New Normal Same Cancer - Shona’s Story

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(Breast Cancer Foundation NZ, 2021)

Watch more personal stories(external link)(external link) from the Breast Cancer Foundation NZ.

NZ Breast Cancer(external link)(external link)  NZ Breast Cancer Foundation, 2013
NZ Breast Cancer facts and statistics(external link)(external link)  NZ Breast Cancer Foundation
Breast cancer(external link)(external link)  NHS Choices, UK, 2014
Living with breast cancer(external link)(external link)  NHS Choices, UK, 2014


A guide for people with breast cancer(external link)(external link) Cancer Society, NZ, 2019
Supporting someone with cancer [PDF, 3 MB] Cancer Society, NZ, 2015
Living well with cancer – eating well [PDF, 5.5 MB] Cancer Society, NZ, 2020 English/te reo Māori [PDF, 5.5 MB]
Living well with cancer – keeping active [PDF, 2.4 MB] Cancer Society, NZ, 2020 English/te reo Māori [PDF, 2.4 MB]
Baring it all(external link)(external link) Breast Cancer Nirvana, NZ, 2014
Having more tests after a mammogram(external link)(external link) BreastScreen Aotearoa, NZ, 2018 English(external link)(external link), Chinese Simplified(external link)(external link), Hindi(external link)(external link), Japanese(external link)(external link), Korean(external link)(external link)
Male breast cancer in New Zealand(external link)(external link) Breast Cancer Foundation, NZ
Risk factors for breast cancer(external link)(external link) Breast Cancer Foundation, NZ
Risk reduction and healthy lifestyle choices(external link) Breast Cancer Foundation, NZ
Benign breast conditions – breast calcifications(external link)(external link) HealthEd, NZ, 2022
Breast cancer: A guide for women with early breast cancer Cancer Society, NZ, 2011 Samoan(external link)(external link)
Breast prosthesis and bra information(external link)(external link) Cancer Society, NZ, 2016
Ductal carcinoma in situ(external link)(external link) Cancer Society, NZ, 2018
Secondary breast cancer(external link)(external link) Cancer Society, NZ, 2019


  1. Breast Cancer Foundation(external link)(external link) NZ, 2017 
  2. Breast cancer facts and risk factors(external link) Patient Info, UK, 2017 


LearnOnline learning resources for health practitioners: Breast cancer(external link)

  • Advanced breast cancer (ABC) clinical management and support: This course will help you gain confidence in detecting the signs and symptoms of local recurrence and metastatic breast disease; become familiar with the common sites of breast cancer metastases and their presentation; become familiar with the clinical management and supportive care of patients with metastatic/advances breast cancer.
  • Familial breast cancer in primary care.
  • Managing breast signs and symptoms – a guide for primary healthcare professionals.
  • Treatment for breast cancer.

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Credits: Original content from Cancer Society of NZ

Reviewed by: Dr Bryony Harrison, MBChB, BMedSci(Hons), DipPCEPE, Junior Doctor.

Last reviewed:

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