Latest Research – Stress and Cancer

Latest Research - Stress and Cancer

Winter 2016, Living Well Magazine

Researchers from Melbourne’s Monash University have found a link between high levels of stress and the spread of cancer.

For years, it has been suspected that high levels of stress may cause cancer and/or accelerate its growth, but neither hypothesis had been proven scientifically.

Now, as reported in the well-respected journal Nature Communications on 1 March 2016, research has shown a direct link between prolonged stress, increased lymphatic activity and the spread of cancer throughout the body.

“We found that chronic stress signals the sympathetic nervous system (SNS) – better known as the ‘fight-or-flight’ response – to profoundly impact lymphatic function and the spread of cancer cells,” Dr Le said.

The lymphatic system is a network of tissues and organs that form part of the body’s immune system. Lymph vessels carry a watery fluid called lymph, which has a role in transporting immune cells around the body, and under normal physiological conditions can help to protect the body against illness. In cancer however, this same system can have a role in the spread and progression of cancer, by providing a passageway for cancer cells that have broken away from a tumour to move to other areas of the body.

The stress response is, of course, a normal part of life, however ongoing stress – such as the kind one might experience during particularly demanding or psychologically challenging periods in our lives – is known to take a toll on health and wellbeing.

What this new research study, led by Dr Caroline Le and Dr Erica Sloan from the Monash Institute of Pharmaceutical Sciences (which was a collaborative study including clinicians from the Peter MacCallum Cancer Centre in Melbourne and the European Institute of Oncology in Milan) established is that a prolonged, ongoing state of stress, creates profound changes to lymphatic functioning that can be very unfavourable to people with cancer.

Regulated by the hypothalamus control centre in the brain, the sympathetic nervous system is responsible for activation of our stress response. After receiving distress signals about perceived danger, the hypothalamus activates our ‘flight or fight’ response through the release of the hormone adrenaline into the bloodstream, which then generates a range of physiological changes throughout the body enabling us to react accordingly to perceived threats.

While studying the effects of the stress response in mice with cancer, the researchers observed that adrenaline increased the number and size of lymphatic vessels in and around the tumour sites, while also increasing the speed of lymph fluid travelling through them.

This heightened activity creates lymphatic ‘highways’ and provides cancerous tumour cells with a more efficient and faster way to multiply and spread to other parts of the body.

The mice were restrained to mimic the way people might feel when they are under significant stress over a prolonged period of time.

“These findings demonstrate an instrumental role for stress in controlling lymphatic function to impact health, and suggest that blocking the effects of stress to prevent cancer spread through lymphatic routes may provide a way to improve outcomes for patients with cancer.”

The study revealed that by inhibiting SNS signalling through pharmacological interventions, they were able to counteract the effects of chronic stress on the lymphatic system and regulate lymphatic vessel functioning to prevent the spread of cancer cells in both the mice and breast cancer patients.

In an article in The Age on 2 March, Dr Sloan emphasised that cancer patients should not feel responsible for their own stress because it can be very difficult to control, especially when diagnosed with a serious illness.

She also said she is hoping the research will lead to new ways of treating cancer in a more holistic way that reduces stress as much as possible along the way.

Le, C. P. et al. Chronic stress in mice remodels lymph vasculature to promote tumour cell dissemination. Nat. Commun. 7:10634 doi: 10.1038/ncomms10634 (2016).