The causes of breast cancer are unknown. But certain things called risk factors can affect a woman’s chances of getting breast cancer. Having risk factors doesn’t necessarily mean you will get breast cancer. Some women get it while others (with the same risk factors) don’t.Even though the exact causes of breast cancer aren’t fully known, it’s likely to be caused by a combination of different risk factors rather than just one.
Age:The risk of breast cancer increases with age. It’s rare in women under 35, and 8 out of 10 breast cancers (80%) occur in women aged 50 or over.
Previous cancer and other breast conditions:Women who’ve had breast cancer or other breast conditions in the past may be at a higher risk of developing breast cancer. This includes women who have previously had: breast cancer, including ductal carcinoma in situ (DCIS) lobular carcinoma in situ (LCIS) an over-production of slightly abnormal cells called atypical ductal hyperplasia radiotherapy to the chest to treat Hodgkin lymphoma at a young age dense breast tissue (when the breast is mostly made up of glandular and connective tissue with very little fatty tissue).
SmHormonal factors:Exposure to the hormones oestrogen and progesterone for long, uninterrupted periods can affect your breast cancer risk. Factors that increase this risk include: taking combined hormone replacement therapy (HRT) containing oestrogen and progesterone over several years (if you’re over 50) not having children or having them later in life not having breastfed or breastfeeding for less than a year starting your periods early (under 12) or having a late menopause (after 50) taking the contraceptive pill (but the risk reduces if you stop taking it).
Lifestyle factors: Close relatives (parents, brothers, sisters, or children) of a person with a history of stomach cancer are somewhat more likely to develop the disease themselves. If many close relatives have a history of stomach cancer, the risk is even greater.
Alcohol: Drinking more than two units of alcohol a day over many years can damage your liver. This increases your breast cancer risk because the liver helps to control oestrogen levels.
Your weight: After the menopause, body fat is the main source of oestrogen. So if you’re overweight, the level of oestrogen in your body may be high, increasing your breast cancer risk.
Smoking:Smoking heavily over many years, especially if you started smoking at a young age, increases your risk.