Risk factors for DCIS

It is not clear what causes ductal carcinoma in situ (DCIS) but some things can increase your risk.

Not as many studies have looked at risk factors for DCIS but they are similar to risks for breast cancer.

Factors that are linked to an increased risk of DCIS include:

• increasing age
• previous history of benign breast disease such as abnormal breast cells in the milk ducts (‘atypical hyperplasia’)
• family history of breast cancer
• genetic mutations that increase the risk of breast cancer such as BRCA1 and BRCA2
• dense breast tissue - when the breasts have more glandular and connective tissue, with little fatty tissue
• not having children
• having your first baby after age 30
• being over 55 at menopause
• being overweight after menopause.

Some other factors may increase risk of DCIS but evidence is inconclusive:

• having your first period before age 12
• lifestyle factors, such as drinking alcohol and smoking
• using menopausal hormone therapy (MHT).