Your blood type could increase your risk of breast cancer by 18% – do you know yours?

ONE of the most common blood types has been identified as a potential breast cancer risk factor by scientists.

Breast cancer is the most common cancer among women worldwide, so identifying risk factors is vital for early detection and prevention.

Woman performing a breast self-exam. — Blood type A was found to be the most common among breast cancer patientsCredit: Getty

While many studies have explored lifestyle and genetic causes, a new study focused on the ABO blood group system.

By pooling global data, the researchers found blood type A was the most common among breast cancer patients, and was linked to an 18 per cent increased risk compared to type O.

In the UK, the most common blood type is O positive (O+), followed by A positive (A+).

O positive is found in about 36 per cent of the population, while A positive is found in around 30 per cent.

AB negative (AB-) is the rarest blood type, making up only one per cent of the population.

The study didn't find a significant association between breast cancer and blood types B, AB, or Rh factor.

Blood groups are determined by the presence or absence of specific antigens on the surface of red blood cells.

The ABO system, which includes the A, B, and O antigens, and the Rh factor (RhD antigen) are the most important determinants of blood type.

Rh-positive individuals have the RhD antigen, while Rh-negative individuals lack it.

The researchers suggested blood group antigens in breast tissue may influence how cancer develops and spreads by interacting with the immune system or affecting cell behaviour.

This study is the most extensive review to date on this topic, based on studies conducted across Asia, Europe, Africa and the Americas.

The researchers also noted regional differences, genetic diversity, and study quality may affect individual results.

But the overall trend supports considering blood type A as a potential risk marker.

This insight could help shape screening guidelines, encouraging earlier or more frequent checkups for women with this blood type.

Further researcher is needed to understand why blood type A may play a role in cancer development.

Blood sample in a test tube. — You can find out your blood type by donation bloodCredit: Getty

To determine your blood type, a sample of your blood needs to be taken and tested, usually by a blood donation service or a doctor.

You can find out your blood type by donating blood through organisations like NHS Blood Donation.

You can also attend NHS Blood Donation's What's Your Blood Type event to register as a donor and get a free blood type test.

Who is more likely to get breast cancer?

ANYONE can get breast cancer and it's not always clear what causes it.

But the NHS says you might be more likely to get it if you:

are over 50
have dense breast tissue – you may be told this after a breast screening (mammogram)
have other people in your family who've had breast or ovarian cancer – you may have inherited a faulty gene, such as a faulty BRCA gene
have certain breast conditions, such as benign breast disease, ductal carcinoma in situ or lobular carcinoma in situ

You may also be more likely to get breast cancer if you have higher levels of the hormones oestrogen, progesterone or testosterone. This may be more likely if you:

started your periods before you were 12, or went through the menopause after you turned 55
have not given birth, or gave birth for the first time after 30
did not breastfeed your children
have used the contraceptive pill in the last 10 years, or take hormone replacement therapy (HRT) – these only slightly increase your risk and for many people the benefits of taking them outweigh the risks

Many breast cancers are also linked to lifestyle, such as smoking.

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