Oestrogen receptor negative (ER−) breast cancer accounts for 15-20% of breast cancers. Unlike ER+ cancer, ER- cancer has few known or modifiable risk factors. It is believed that fruit and vegetable consumption reduces breast cancer risk but, for this tumour type, evidence has proved inconclusive as few studies focus on ER- tumours and few cases are presented in mixed studies. A research team from Harvard have recently examined pooled data to study the relationship between the consumption of fruit and vegetables and the risk of breast cancer by hormone receptor status1.
Researchers found no association between fruit and vegetable consumption and risk of breast cancer overall or for ER+ breast cancer specifically, but did find that high fruit and especially vegetable consumption was protective of ER– breast cancer. The reason behind this association with ER– but not ER+ is not yet known, but further research has now been called for.
Further work has also reported that higher intakes of berries and peaches were associated with lower risk of ER- breast cancer in post-menopausal women2. However, the authors say that these results are exploratory and need to be confirmed in more studies.