It would appear that red meat and processed meat increases the risk of breast cancer by 6% and 9% respectively but only some studies show this; while switching from red to white meat reduces risk.
Back in 2007, researchers at Brigham and Women’s Hospital and Harvard Medical School in Boston were studying women who were part of the Nurses’ Health Study II from 1989 to 2003, and concluded that those consuming one and a half helpings of red meat per day had twice the hormone receptor-positive breast cancer risk of those consuming only 3 helpings per week.
The possible causes included hormones used in US cattle (not permitted in UK meat), heterocyclic amine carcinogens produced by the cooking process, IGF-1 and even haem-iron a known link to hormone induced cancer. 90,000 women featured in the study, which is recorded in the Archives of Internal Medicine..
One and a half helpings of red meat per day is a substantial amount. What about the average person?
In fact, this research is just a part of the ongoing debate about red meat, processed meat and cancer. A 2018 meta analysis (1) published in the International Journal of Cancer attempted to clear up the issues once and for all. The conclusions of this study were that in case-controlled research red meat increased breast cancer risk by 6%, and processed meat consumption was associated with a 9% increased risk.
However, in the observational studies chosen for the met-analysis there was no increased risk found for either red meat or processed meat.
The debate continues but it seems sensible to cut back on red meat and processed meat consumption if you want to avoid breast cancer.
This is borne out by the most recent study, in which white meat was substituted n the place of red meat and showed a 28% decrease in breast cancer risk. In the study (2) again in the International Journal of Cancer, August 2019, the women in the highest quartile of red meat consumption had a 23% increased risk of invasive breast cancer over those in the lowest quartile.
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References
- https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.31848
- https://onlinelibrary.wiley.com/doi/10.1002/ijc.32547