Women with the highest levels of education have around 40% higher risk of situ breast cancer, 20% higher risk of invasive breast cancer and 20% higher risk of ER positive breast cancer. This is in comparison to women with the lowest education level in the study.
These highly educated women also faced a higher risk of developing PR-positive, PR-negative, HER2-positive, and HER2-negative subtypes of the cancer. IARC scientist Dr Salvatore Vaccarella, a co-author of the study explained the potential connection has more to do with the type of person that’s likely to study more, rather than their actual schooling.
He said: “This study is the first comprehensive analysis of this scale looking at how socioeconomic factors, like education level, are associated with the risk of breast cancer subtypes.
“The higher risk of ER-positive and other good-prognosis subtypes among highly educated women partly reflects their childbearing and lifestyle patterns, as well as their greater participation in screening programmes.”
IARC scientist Dr Margherita Pizzato, the lead author of the study said: “Understanding how social factors, like the level of education, influence the risk of different breast cancer subtypes is crucial.
“It provides insights not only into the etiology of the disease and how we can prevent it but also into the broader inequalities that affect health outcomes across different communities.”
Researchers found the biggest explanation for this connection between education and breast cancer was choices around family. Highly educated women were generally older when they had their first pregnancy and had fewer pregnancies in total than women with less education.
Cancer Research UK noted: “Having children and in particular having a child at younger age can slightly lower your risk of developing breast cancer. The risk gets lower the more children you have.”
Highly educated women were also more likely to drink a lot of alcohol. Alcohol increases the risk of multiple cancer types and is classified as a group 1 carcinogen by the IARC due to its effects.
These women also tended to use oestrogen-progestin therapies which can increase the risk of breast cancer. These hormones are found in medications like birth control and HRT.
The NHS estimates around five extra cases of breast cancer arise for every 1,000 women taking HRT for five years or longer. However, the IARC experts found these lifestyle and reproductive differences only explained between 20% and 40% of the difference in breast cancer risk for highly educated women.
What exactly is driving the rest of the risk is currently unknown. The International Agency for Research on Cancer, part of the World Health Organisation, analysed over 300,000 women as part of the “most extensive” study on this correlation ever done. The study was published in the International Journal of Cancer.
