And now scientists also know how to prevent it from happening — at least in mice.
The medical community has long debated how stress affects a patient’s prognosis, and while stress has not been proven to cause cancer, scientists now say it might have a significant role in how it spreads.
A Monash University research team led by cancer biologist Dr Erica Sloan studied how stress drives metastasis — the spread of an existing cancer from the original tumour — in mice with breast cancer.
“Stress sends a signal into the cancer that allows tumour cells to escape from the cancer and spread through the body,” Dr Sloan said.
“The stress is sort of acting like a fertiliser and helping the tumour cell take hold and colonise those other organs.”
Dr Sloan said although it was already known cancer could spread through the lymphatic system, her team discovered stress transformed the network into a super highway that allowed the cancer cells to travel at much faster speeds.
The group placed mice with cancer in confined spaces in order to mimic the physiological and emotional effects of stressed humans.
Dr Caroline Le, who was part of Dr Sloan’s team, said the effect the stress had on their cancer was marked.
“You see six times more spread of cancer in stressed mice compared to control mice,” she said.
Stress levels typically increase in a patient after a cancer diagnosis.
The good news is Dr Sloan’s research team found an age-old class of medication — currently used for high blood pressure and cardiac arrhythmia — could prevent the stress facilitating the cancer’s spread.
The medication contains beta blockers which prevent the stress response by competing with adrenalin to limit heart rate and blood pressure increase.
When the beta blockers were given to the mice with cancer, the stress response was completely negated. The stress no longer restructured the lymphatic system that led to the increased cancer spread.
Anaesthetist Dr Jonathan Hiller is currently conducting a human pilot trial at the Peter MacCallum Cancer Centre in Melbourne. His trial is focusing on anxiety in female surgical patients recently diagnosed with breast cancer.
“We’ve chosen the peri-operative period because, as an anaesthetist, we often see women have a state of increased stress and anxiety at the time of surgery, and the build-up to surgery following diagnosis can be incredibly anxiety provoking,” Dr Hiller told Catalyst.
In his double-blind trials, patients are being given either the beta blocker Propanolol or a placebo, and their stress levels before and after surgery are being recorded via blood samples.
Stress signatures which are present in white blood cells are being analysed to see if the beta blocker can change the stress signatures at the time of surgery.
Dr Hiller’s study is ongoing, but depending on the results of the trial, researchers may be able to develop a cancer-specific beta blocker that is designed to target tumours, not the heart.