A study observing changes in healthy breast cells may explain why women who have their first child later in life appear to have an elevated risk of breast cancer.

 

Researchers from Imperial College London examined healthy breast cells from 29 women who had given birth at different ages and women who did not have any children, to look at genetic mutations and how cells divide.

 

This is the first study of its kind to examine the entire genome of healthy, non-cancerous breast cells in women who have given birth at different ages.

 

Key questions remain including whether breastfeeding, age at first period and menopause affect the risk of breast cancer.

 

Lead author of the study, Dr Biancastella Cereser, from Imperial’s Department of Surgery and Cancer, said: “In recent decades, women have begun having children later because of societal changes and personal preferences. Previous research has found that this is associated with a heightened breast cancer risk.”

A woman’s risk of developing breast cancer is influenced by pregnancy – but the relationship is complex.

Several studies report that young first-time mothers have around a 20-35% lower risk of developing breast cancer in the long-term when compared with women who do not have any children.

However, the risk of breast cancer then progressively increases for mothers who have their first child after the age of 24 – with a 5% increase in risk for every 5 years.

In the latest study, Dr Cereser and team examined  the cellular and genetic changes that take place in normal, healthy breast tissue in different groups of women: first-time mothers under 25 years; first-time mothers between 35 and 55; and women with no children (aged between 25 and 53).

The research is published in the journal Nature Communications.