Stress—also known as psychological stress—describes what people experience when they are under mental, physical, or emotional pressure. Stressors—factors that can cause stress—can arise from people’s daily responsibilities and routines, including work, family, and finances. Other stressors include external factors such as early life adversity, exposure to certain environmental conditions, poverty, discrimination, and inequities in the social determinants of health. Serious health issues, such as a cancer diagnosis in oneself or a close friend or family member, can also cause stress. 

The body responds to external stressors by releasing stress hormones (such as epinephrine and norepinephrine) that increase blood pressure, heart rate, and blood sugar levels. This response, often referred to as the fight-or-flight response, helps a person act with greater strength and speed to escape a perceived threat.

Although the fight-or-flight response helps the body manage momentary stress, when this response is caused by long-term, or chronic, stress it can be harmful. Research has shown that people who experience chronic stress can have digestive problems, heart disease, high blood pressure, and a weakened immune system. People who experience chronic stress are also more prone to having headaches, sleep trouble, difficulty concentrating, depression, and anxiety and to getting viral infections, including SARS-CoV-2, the virus that causes COVID-19.

Although chronic stress can lead to many health problems, whether it is linked to cancer is not clear. Studies conducted to date have had varying results. For example, 

• One case-control study among Canadian men found an association between workplace stress and the risk of prostate cancer, whereas a similar study did not find such an association. 
• A prospective study among more than 100,000 UK women reported no association between the risk of breast cancer and perceived stress levels or adverse life events in the preceding 5 years.
• A 15-year prospective study of Australian women at increased risk of familial breast cancer found no association between acute and chronic stressors, social support, optimism, or other emotional characteristics and the risk of breast cancer. 
• In a 2008 meta-analysis of 142 prospective studies among people in Asia, Australasia, Europe, and America, stress was associated with a higher incidence of lung cancer. 
• A 2019 meta-analysis of nine observational studies in Europe and North America also found an association between work stress and risk of lung, colorectal, and esophageal cancers. 
• A meta-analysis of 12 cohort studies in Europe found no link between work stress and the risk of lung, colorectal, breast, or prostate cancers.

Even when stress appears to be linked to cancer risk, the relationship could be indirect. For example, people under chronic stress may develop certain unhealthy behaviors, such as smoking, overeating, becoming less active, or drinking alcohol, that are themselves associated with increased risks of some cancers.

Evidence from laboratory studies in animal models and human cancer cells grown in the laboratory suggests that chronic stress may cause cancer to get worse (progress) and spread (metastasize). For example, some studies have shown that when mice bearing human tumors were kept confined or isolated from other mice—conditions that increase stress—their tumors were more likely to grow and metastasize. 

Laboratory studies have found that norepinephrine, released as part of the body’s fight-or-flight response, stimulates angiogenesis and metastasis. This hormone may also activate neutrophils, a type of immune cell. In some cases, neutrophils can help tumors grow by shielding them from the body’s immune system; they may also “awaken” dormant cancer cells.

Chronic stress may also lead to the release of a class of steroid hormones called glucocorticoids. Glucocorticoids may inhibit a type of tumor cell death called apoptosis and increase metastasis and resistance to chemotherapy. They may also prevent the body’s immune system from recognizing and fighting cancer cells. 

Although some studies have reported decreased survival among people with cancer who are experiencing stress, the evidence that stress directly affects survival remains weak overall. 

Emotional and social support can help patients learn to cope with stress. Such support can reduce levels of depression, anxiety, and disease- and treatment-related symptoms among patients. 

There is some evidence that successful management of stress through social support is associated with better clinical outcomes for people with breast cancer. Social support has also been linked to lower levels of stress-related hormones that can promote tumor progression in ovarian cancer. 

Another approach to cope with stress is by being physically active. A report of the 2018 American College of Sports Medicine International Multidisciplinary Roundtable on Physical Activity and Cancer Prevention and Control found “sufficient” evidence to conclude that moderate-intensity physical activity during and after cancer treatment can reduce anxiety and depressive symptoms among cancer survivors. There is also evidence suggesting that physical activity is helpful in preventing depression among survivors of childhood cancer.

People who are experiencing significant stress with a cancer diagnosis may also want to consult their doctors about a referral to an appropriate mental health professional. In fact, some expert organizations recommend that all cancer patients be screened with an appropriate tool, such as with a distress scale or questionnaire, soon after diagnosis as well as during and after treatment to gauge whether they need help managing stress or are at risk for distress.

Treatment of significant distress, depression, and anxiety under the care of a mental health professional might include psychotherapy (talk therapy) and/or antidepressants or other medication. The choice of treatment should be personalized, ideally as a joint decision between the patient and the health care provider. 

Researchers are studying novel psychotherapeutic approaches to lessen depressive symptoms such as distress and hopelessness in people with cancer. In one randomized clinical trial of people who had recently been diagnosed with advanced cancer, three to six sessions of a tailored psychotherapy intervention reduced symptoms of depression. Results from the trial also suggest that the approach may help prevent the onset of depression in those with advanced disease.

Another randomized clinical trial compared two different mindfulness-based cognitive therapy interventions—one delivered in person, the other electronically—with usual treatment in reducing psychological distress in people with cancer. Both interventions reduced elements of distress like fear of cancer recurrence and increased mental health–related quality of life, mindfulness skills, and positive mental health.

A resurgence of academic research into the therapeutic potential of psychedelic drugs has produced preliminary evidence for the possible role of psilocybin-assisted psychotherapy in the treatment of cancer-related anxiety, depression, and existential distress.