Beware: chronic stress can build “lymphatic highways” that allow cancer cells to move quickly and efficiently spread in the body.
The mice study led by Australian scientists also found that a known blood pressure drug, on the other hand, may reduce this risk of cancer spread.
The researchers from Monash University reported that chronic stress is detrimental to cancer patients in that it increases the size and number of lymphatic vessels in and around tumors, as well as increases fluid flow in existing vessels.
High stress levels then create cancer highways that allow malignant cells to more freely move around.
“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,” says Dr. Caroline Le, who undertook the study as part of her Ph.D. research.
According to previous studies, stress hormones like adrenaline and noradrenaline can influence the formation of blood vessels, which is key in disease spread.
The lymphatic system, comprising a network of tubes draining fluid from tissues back into the bloodstream, is tasked to carry immune cells throughout one’s body to fight disease – but is also instrumental in transporting cancer cells around. The team sought to precisely monitor tumor cell movement through this network by using a fluorescent marker and advanced imaging methods.
The results, however, also showed that while adrenaline clearly acted through specific cell receptors, certain drugs can be used to block the pathways at work.
Dr. Le and co-author Dr. Erica Sloan then used a drug known as propranolol to block adrenaline’s action in the stressed mice and regulate lymphatic function to prevent cancer cell spread. This medication is a beta blocker, widely used at present for treating hypertension.
The team looked at data from almost 1,000 breast cancer patients in Italy, analyzing whether their beta-blocker intake had any impact on their risk of metastasis.
"When tracked over about seven years, it turned out that those that had been taking beta-blockers also showed far less evidence of tumor cells moving into the lymph nodes and then disseminating to other organs like the lung,” says Dr. Sloan, now conducting a pilot study to see if propranolol medication will reduce the risk of tumor spread.
The findings were published in the journal Nature Communications.
Photo: Sodanie Chea | Flickr