GPs should consider childbirth as a risk factor for breast cancer, according to a new study.
Researchers found that compared with women who have never given birth, women who have are at an increased risk for breast cancer for more than 20 years after giving birth.
The study, published in the Annals of Internal Medicine, used a pooled analysis of individual-level data from 15 prospective cohort studies, including women younger than 55 years, across three continents.
Altogether, during 9.6m person-years of follow-up, there were 18,826 incident cases of breast cancer diagnosed among 889,944 women.
The study said: ‘Compared with nulliparous women (those who have never given birth), parous (those who have given birth) women had a hazard ratio for breast cancer that peaked about five years after birth before decreasing to 0.77 after 34 years. The association crossed over from positive to negative about 24 years after birth.
‘The overall pattern was driven by oestrogen receptor-positive breast cancer; no crossover was seen for oestrogen receptor-negative cancer.’
Estrogen receptor-positive breast cancer is the most common type, with about 70% of all cases being this type.
The authors concluded: ‘Compared with nulliparous women, parous women have an increased risk for breast cancer for more than 20 years after childbirth. Health care providers should consider recent childbirth a risk factor for breast cancer in young women.’
In November, the Government announced a ‘major overhaul’ of the UK national cancer screening programmes, including cervical, breast and bowel.