There are two ways that cancer spreads throughout the body - through the blood vessels or through the lymphatic system, which is a network of tubes that drain fluid from tissue back into the bloodstream. But once it's out, it can form deadly secondary tumours, which is why it's so important for doctors to remove cancer as quickly as possible once it's detected.
Scientists already know that stress hormones can increase blood vessel formation, giving cancerous cells more potential escape routes, but until now it wasn't clear whether they also influenced the lymphatic system.
Not only that, the stress hormone actually physically changed the lymph vessels draining out of tumours, allowing cancerous cells to escape to other parts of the body faster.
"So not only do you get new freeways out of the tumour but the speed limit is increased and so the tumour cells can flow out of the tumour much more rapidly," said Sloan.