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Ask the Expert: Cancer and Stress

9 min read  |  May 10, 2023  | 
Disponible en Español |

Firdaus Dhabhar, Ph.D., is a professor in the Department of Psychiatry and the Department of Microbiology and Immunology at the Miller School of Medicine and the Sylvester Comprehensive Cancer Center at the University of Miami Health System. He is also the director of Scholarly Concentration in Advancing Mind-Body Medicine at Miller’s Office of Medical Education.

In this Q&A, Dr. Dhabhar discusses different types of stress and their impact on cancer.

How do you define stress in general, and what is the difference between “good” and “bad” stress?

Dr. Dhabhar: Stress is a constellation of events that begins with a stimulus (the stressor) that induces a reaction in the brain (stress perception and evaluation). This process activates fight-or-flight systems in the body (the biological stress response). A biological response is essential in order for stress to affect the brain and body.

The duration of the stress is key in distinguishing between good stress and bad stress. Short-term stress lasts a few minutes to a few hours. It is Mother Nature’s way of helping us deal with threatening or challenging situations. It can have beneficial effects and is therefore considered good stress. In my lab, we work on generating and harnessing good stress to enhance health and healing.

When the stress response is activated for weeks, months, or years, it is considered chronic or bad stress. Mother Nature did not intend for the stress response to last for long periods. In our Department of Psychiatry and in my lab, we also work on investigating and reducing or eliminating bad stress and its harmful effects.

How does the body show signs of good stress, and how does that differ from the way bad stress affects us?

Dr. Dhabhar: During good stress, there are increased concentrations of stress hormones in our bloodstream. The main hormones are epinephrine (adrenaline), norepinephrine, and cortisol. These hormones serve as the brain’s alarm signals. They tell the body that something threatening or challenging is happening or about to happen.

We discovered that an important feature of good stress involves rapid, significant changes in immune cell distribution in the body. These immune cells act like the body’s “soldiers,” quickly moving from their “barracks” (organs such as the spleen) through the body’s “boulevards” (blood vessels) and onto places in the body where they may need to start healing a wound or fighting an infection. If no infectious agent enters the body, or there is no wound, everything goes back to normal resting conditions in about three to four hours after the stress response ends.

A key feature of good stress is for the brain and body to mount a rapid and robust stress response as soon as you need it and then to shut it down as soon as possible.

In contrast, chronic or “bad” stress can induce long-term biological changes such as increased low-grade inflammation, accelerated biological aging, and disrupted sleep and day-night rhythms.

Can stress cause cancer?

Dr. Dhabhar: Research shows that stress does not cause cancer per se. However, chronic stress can suppress protective immunity, enhance harmful inflammation, and cause other biological changes that can favor the formation of some cancers.

Our group does most of its research in humans, but we also do some work in mice. We and others have shown that even in animal models, chronic stress can create conditions that favor the development of cancer.

It’s very important, however, to understand that getting cancer is nobody’s fault. When I speak at cancer survivor meetings and clinician conferences, I often hear that some patients blame themselves for not having managed stress better and for not being able to get well. It’s extremely important to understand that such self-blame is not deserved, justified, or helpful.

Why, when, and how we become stressed, and how that stress affects us, involves a myriad of complex factors and interactions among them. We’d have to be superhuman to handle everything just right. It’s not helpful to think, “It was within my control, and I didn’t do it right.” It’s better to try your best to practice good habits as much as reasonably possible and to do your best to stay away from harmful things such as smoking and substance abuse.

It’s also important to remember how stressful a cancer diagnosis can be and the tremendous hit the treatment itself can have on the patient/survivor.

What are some of the effects of ongoing stress on patients with cancer and on cancer survivors?

Dr. Dhabhar: For most people, cancer diagnosis and treatment lead to tremendous amounts of stress. There’s not only the psychological stress of dealing with a very disruptive, potentially terminal disease but there are also biological changes brought on by cancer treatments. Some treatments actually activate the body’s stress response through biological factors that can directly affect the brain.

My lab studies the effects of good versus bad stress in the context of recovery from gastrointestinal cancer surgery and the ensuing oncological outcomes. This is a collaboration with my colleague Nipun Merchant, M.D., and his team. We hope to expand our study to look at breast surgery for cancer and cosmetic purposes. The breast surgery expansion would be with my colleague Devinder Singh, M.D., and others in UHealth’s Division of Plastic Surgery. Our goals are to try to understand the effects of good stress around the time a patient undergoes surgery and around different treatment procedures they receive. Another goal would investigate long-term stress and psychosocial factors that can buffer or worsen the harmful effects of chronic stress in the context of cancer and its treatment. We also aim to understand the elements of cancer treatment that are the most damaging psychologically, biologically, and physiologically, and hope to formulate interventions to help patients.

Most importantly, Sylvester and UHealth want to partner with the community to learn what is important to folks who are in this predicament. We welcome input from patients, survivors, their families, and loved ones. If you have ideas of what we could do with our research efforts that would help you or your loved ones, please email me at [email protected].

Can you talk about the importance of having support if you are diagnosed with cancer or going through treatment?

Dr. Dhabhar: Genuine support and caring can be extremely helpful during any challenging period in life, including dealing with cancer. Studies conducted by our group and other investigators have found that social support is a significant buffer against the multiple harmful effects of chronic stress. Some studies show actual biological differences between people reporting high versus low levels of social support. We observed that harmful biological factors are lower in people who report having social support (i.e., knowing that there are one or two people in their lives they can count on) than in people who report not having much social support.

Support often means genuinely being there for someone as much as you reasonably can. It could mean helping someone navigate the logistics of the health care system, helping a friend or family member with their day-to-day chores and responsibilities during cancer diagnosis, treatment, and recovery, driving them to and from treatment visits, or actions that say, ‘I am here for you.’

Our physician colleagues and health care teams who treat cancer patients do a tremendous amount to help patients. It is also possible to help a patient even if you don’t have an M.D., and you haven’t spent a lifetime studying the latest therapies. Little acts of caring and kindness sometimes make a big difference. Together with social support, factors such as compassion, helpfulness, and giving behaviors and attitudes could go a long way toward reducing the stress many people with cancer experience.

What does your research show about the effects of good stress in the context of surgery, vaccination, and cancer?

Dr. Dhabhar: Our research has shown that a short-term stress response can naturally enhance the body’s own immune system during wound healing, including surgical healing, vaccination, and perhaps also in the context of some types of cancer. The short-term stress response enhances immune function by: 1) delivering more immune cells to a site of wounding, surgery, vaccination, or cancer; 2) Increasing the ability of immune cells to function; and 3) By stimulating the production of certain important immune molecules (cytokines). 

Thankfully, we were able to take our research from lab to clinic in one step. We showed that patients who mount a “good” stress response while undergoing surgery show significantly better recovery (and report less pain) than patients who do not mount a good stress response during surgery. This difference in recovery profiles lasted for the entire length of our study, which was almost a year long.

It has also been shown that if you induce a short-term stress response by making someone exercise, do mental arithmetic, or speak in front of an audience before being vaccinated, their vaccine response can be enhanced.

We are trying hard to take these findings to the next stage, to figure out how to naturally induce good stressors to make vaccines work better and to enhance surgical healing. Studying the effects of good stress in the context of cancer is still in the pre-clinical stages. We are trying to secure funding to do more experiments in the lab before we can see what can be done in the clinic.

However, we do know from studies of mice with tumors that if we expose the mice to short-term stress once a week, we can enhance the natural immune response that attacks the tumors and begins to naturally regress tumors using the mouse’s own immune system. It may not apply to all types of cancers in all models, but in the model we study, some tumors do regress. More research is needed, but the findings are exciting and promising – if it works, we may be able to use the biology of the short-term stress response to harness the body’s own immune system to fight the cancer, at least under some conditions.

Dr. Dhabhar welcomes input from cancer patients and survivors, their families, and loved ones on ways his team can help, email him at [email protected].


Q&A compiled by Nancy Moreland, a contributing writer for UMiami Health News. She has written for several major healthcare systems and the Centers for Disease Control and Prevention. You can also find her writings in the Chicago Tribune and U.S. News & World Report.

Tags: cancer, Dr. Firdaus Dhabhar, stress

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