Risk factors and causes
We don’t completely understand what causes DCIS. It’s likely to happen as a result of multiple factors.
Things that can increase your risk of developing a disease are called risk factors. There are a number of risk factors that may slightly increase a woman’s risk of getting DCIS or breast cancer.
However, women with no risk factors can still develop DCIS, and there are women with risk factors who don’t get DCIS.
The risk factors for DCIS and invasive breast cancer are similar and are explained here.
The risk of DCIS increases with age - it’s rare in women under the age of 35.
Long, uninterrupted periods of exposure to the hormones oestrogen and progesterone can increase the risk of breast cancer. This may happen if:
your period started at an early age
your menopause starts late
you don’t have children or have them later in life.
Family history of breast cancer
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Sometimes, DCIS is linked to an inherited breast cancer gene. This is more likely if there’s a strong history of breast cancer in your family. The chances of there being a breast cancer gene in your family increase if:
two or more close blood relatives on the same side of the family have had breast or ovarian cancer – close relatives are your parents, children, brothers, sisters, aunts, uncles and grandparents
a close relative has had breast or ovarian cancer at a young age (under 40)
a close relative has had breast cancer in both breasts.
The genes most commonly linked to an increased risk of breast cancer in families are BRCA1 and BRCA2. If you’re concerned about a history of breast cancer in your family, talk to your GP or breast specialist. They may refer you to a family cancer clinic.
If you’re worried about cancer running in your family, we have more information available about breast cancer. We also have more information about cancer genetics.
Online self-assessment tool
You might want to use OPERA, our Online Personal Education and Risk Assessment tool, to check whether breast or ovarian cancer in your family may be due to inherited genes. OPERA gives you a personalised assessment of your genetic risk with further information and support. You could also print out your assessment and take it to your GP to discuss. OPERA isn’t intended to replace professional genetic counselling services, so if you’re concerned, you should still consult your doctor.
Other breast conditions
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Your risk of developing DCIS is also higher if you’ve had:
The following lifestyle factors may slightly increase your risk:
drinking more than two units of alcohol every day over many years
being overweight after the menopause.