Various scientific studies reveal the most common cause of cancer

Years of smoking, drinking and eating too much are thought to damage DNA and weaken the body's defenses, creating an ideal environment for cancer to form.

But some research shows that a single traumatic event may be linked to the development of the deadly disease years later.

A bitter divorce, death of a family member, or severe injury can leave a deep impact on you, impairing how you respond to stress for the rest of your life and possibly increasing your risk of cancer.

A 2019 study of more than 54,000 women found that women who had experienced a traumatic event, such as a car accident or assault, and had symptoms of post-traumatic stress disorder had twice the risk of developing ovarian cancer compared to women who had not experienced trauma.

A 2022 study of 278 patients found that the majority of patients diagnosed with head, neck, and pancreatic cancer experienced a stressful event within 5 years of their cancer diagnosis.

However, other studies have found less conclusive links between cancer and stress. A 2016 study of more than 100,000 women in the United Kingdom found no link between stressful life events and breast cancer risk.

Such studies have led Dr. Andrea Lynn Roberts to say that the link between cancer and stress is not very strong scientifically.

“It is true that stressful events that lead to PTSD or lifelong emotional problems can affect your health and increase your risk of developing a range of medical conditions,” she explained. “The link between stress and heart disease, for example, is much stronger than the link to cancer. I think if you have high levels of stress, cancer is not something you should be worried about.”

For decades, scientists have investigated the relationship between cancer and stress.

“It can have a profound effect on how your body’s systems function,” said Lorenzo Cohen, MD, director of the integrative medicine program at MD Anderson. “Our best guess is that stress makes your body more susceptible to cancer, meaning it suppresses your body’s natural defenses against cancer and other diseases.”

A one-time traumatic event can lead to depression, anxiety or post-traumatic stress disorder, all of which can lead to lifelong problems, according to experts.

Doctors believe that chronic stress causes cellular changes in your body, which may eventually lead to cancer, according to Dr. Cohen.

Under extreme stress, the body constantly produces hormones such as cortisol and adrenaline, which triggers the body's "natural alarm system."

And if you can't calm yourself down over a long period of time, it can affect your body, weaken your immune system, and cause digestive problems, which can make it easier for cancer to grow, says Dr. Anil Sood, professor of gynecologic oncology and reproductive medicine at MD Anderson.

Anyone who is stressed can also act in ways that increase their risk of cancer, such as smoking, drinking alcohol or not exercising, according to the National Cancer Institute (NCI).