Last month, the Breast Cancer Now Generations Study was in the news again with results showing that day-to-day stress is unlikely to cause breast cancer. The link between stress and breast cancer is a topic that comes up a lot in the media, maybe because as the song goes, so much of modern life is spent “under pressure”. So we wanted to talk a bit more about the evidence and what the recent Generations Study results add to this.
Kicking the evidence around the floor
When considering how anything is linked to breast cancer, it’s important to remember that there’s no one single cause of cancer – it results from a combination of our genes, the way we live our lives and our surrounding environment.
This makes it tricky to unravel the links between different life experiences and breast cancer, and for stress in particular, there is the added challenge of measuring it consistently and precisely, when we all experience stress so differently.
But under pressure we’re breaking…
Almost everyone experiences stress at points throughout their lives, so we all know that stress affects us in ways others than just making us feel bad. Having a stressful time in your life can come hand in hand with unhealthy behaviours such as putting on weight and drinking alcohol. These are things that we know do increase people’s risk of breast cancer but they are indirect effects of stress, rather than biological changes in the body directly caused by stress.
Pressure on people, people analysing the Generations Study
However, there have been a few studies looking for a direct link between stress and breast cancer, analysing several big groups of data on stress and cancer (known as meta-analyses) and also looking at stress and cancer in animal studies.
None of these have provided conclusive evidence for a link between stress and breast cancer. Because the question of stress and breast cancer still comes up, and because there are suggested (but not proven) biological reasons why stress could feed into the causes of cancer, scientists running the Generations Study wanted to investigate further.
Our researchers looked at day-to-day stress in the five year period before women joined the study. This was via a question which people answered when entering the study asking if they felt they had experienced stress “never”, “occasionally”, “frequently” or “continuously” over the past five years.
For the 1,783 women who had gone on to develop breast cancer, the researchers found no link between how frequently women had experienced stress and their chances of getting breast cancer. Importantly, they also ruled out all the factors that we know cause breast cancer before they looked at stress.
But should we give stress one more chance?
So does this mean that we can rule out stress as a cause of breast cancer? Well this analysis of the Generations Study, which is the largest study to date to investigate the link, seems to show it’s unlikely that stress causes breast cancer.
As always, further evidence might change this, and the most important thing is that people are helped through times of stress so that they don’t have to resort to unhealthy behaviours that do increase breast cancer risk like drinking and not exercising.
But for now it looks like the link between stress and breast cancer is, firmly, under pressure.