No association found between psychological stress and breast cancer incidence

A recent study carried out at The Institute of Cancer Research (ICR; London, UK) and recently published in Breast Cancer Research has found no association between psychological stress and the incidence of breast cancer.

Utilizing the Breast Cancer Now Generations Study – a study designed to further the understanding of the aetiology of breast cancer – the ICR researchers investigated the link between stress, adverse events and breast cancer incidence.

In excess of 106,000 women were involved in the prospective cohort study, which evaluated the incidence of breast cancer in relation to stress variables and adverse events.

In order to prevent any other aetiological factors from affecting the psychological stress variables being studied, the team collected data for known breast cancer risk factors s such as alcohol consumption, obesity, cigarette smoking, a family history of breast cancer and socio-economic status.

Overall, the study demonstrated that relative risks for breast cancer in respect to the frequency of stress variables were not statistically significant in the 5 years following entry into the study.

The study did find, however, that the risk of having breast cancer was increased in women who had lost their mother when they were younger than 20. However, this was thought to be attributed in part to a genetic predisposition as the association was not found to be statistically significant once mothers who had had ovarian or breast cancer were excluded.

Study leader Dr Schoemaker, commented: “It’s always a challenge to try to disentangle which of life’s many experiences and behaviors might influence the risk of cancer. Our study has analyzed very large amounts of data from women over many years, and has provided good evidence that stress is unlikely to increase the risk of developing breast cancer. Stressful life events are common and many women will have experienced them in the run-up to being diagnosed with breast cancer, but our results suggest that those stressful events are unlikely to be the cause of the disease.”

The researchers are looking to continue the study in partnership with the Breast Cancer Now Generations Study, as part of a larger study that will track the women over the next 40 years, recording their lifestyle information and monitoring which individuals develop breast cancer.

Baroness Delyth Morgan, Chief Executive at Breast Cancer Now, said: “Many women often question whether their breast cancer could have been triggered by stress or a particularly difficult experience. This ground-breaking study provides the most robust evidence to date that stress itself is unlikely to be a biological cause of the disease.”

Source: Schoemaker MJ, Jones ME, Wright LB et al. Psychological stress, adverse life events and breast cancer incidence: a cohort investigation in 106,000 women in the United Kingdom. Breast Cancer Res. DOI: 10.1186/s13058-016-0733-1 (2016); ICR press release