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What is the relationship between stress and cancer?

Research has long supported a connection between inflammation and cancer. But what scientists are now learning is the implication inflammation may have on the relationship between psychological stress and cancer.

Research has long supported a connection between inflammation and cancer. But what scientists are now learning is the implication inflammation may have on the relationship between psychological stress and cancer. So far, research has stopped short of concluding that chronic stress causes cancer, but enough is understood about the association to suggest that being in a constant state of stress is a risk factor for cancer and its progression, and that inflammation is likely to blame. “Chronic stress creates something of a perfect storm where precancerous cells can grow and flourish,” says Ankur Parikh, DO, Medical Director of Precision Medicine at Cancer Treatment Centers of America® (CTCA).

Fight or flight

The natural stress response, often called the “fight or flight” reaction, occurs when the body encounters a perceived threat, such as a rustling in the bushes or a sudden, loud noise. When scared or caught off-guard, the body releases adrenaline, cortisol and other hormones. Adrenaline causes the heart rate and blood pressure to rise. Cortisol, the primary stress hormone, triggers an increase in sugars, or glucose, in the blood. Typically, the stress response is self-limiting, meaning hormone levels and, consequently, heart rate, blood pressure and sugar levels, almost immediately return to normal. But when the body is stressed on an everyday basis, by factors like a demanding work schedule or a cancer diagnosis, the stress responses don’t always shut off.

The amount of stress anyone may experience largely depends on the person. Someone whose fight- or-flight system doesn’t shut off may have an overactive stress response, caused perhaps by slight differences in the genes that control stress. Or the deficiency may be caused by past traumatic events, such as abuse suffered as a child. Either way, a stress response system that doesn’t turn off generally causes inflammation, which may increase the risk for several health problems, such as anxiety, depression, heart disease and cancer.

“What we’re finding is that when you’re stressed, your body releases a surge of hormones, including adrenaline and cortisol, that triggers various inflammatory responses,” Dr. Parikh says. “When you’re in a constant state of psychological stress, those triggers don’t shut off, which could lead to chronic inflammation and, potentially, cancer growth or cancer metastasis.”

A perfect storm

People with chronic inflammatory bowel disorders like Crohn’s disease and ulcerative colitis tend to have chronic inflammation, for example, and are at a higher risk for colorectal cancer. Crohn’s disease and ulcerative colitis are autoimmune diseases, which develop when the immune system attacks healthy cells in the body by mistake. “It’s a case of a hospitable environment being created where cancer cells can develop and grow,” Dr. Parikh says.

It’s the same type of environment that develops when someone is in a state of constant stress, Dr. Parikh says. “This isn’t a case where we know that a specific gene mutation predisposes you to a chronic inflammatory state, but there is a lot of literature linking chronic stress and chronic inflammation, which could lead to an ideal environment for cancer to develop, or, if it’s already present, to grow and spread.”

In patients who already have cancer, studies have found that stress is linked to tumor growth. “We know that high-stressed cancer patients tend to have a harder time in treatment and recovery, and it makes sense that cancer might be harder to treat or more aggressive in these patients,” Dr. Parikh says.

While more studies are needed to further clarify the connection, experts say the current body of research is enough to suggest a connection between stress, inflammation and cancer—especially in people who already have the disease. That means everyone, including patients, should do what they can to change their lifestyle to reduce stress, which may help to improve their overall health and lower their risk of certain cancers, Dr. Parikh says.

Learn more about inflammation’s cancer connection.