Years of smoking cigarettes, binge drinking and over-eating. These are all factors that cause cancer.
Over time, these habits are thought to cause damage to DNA and weaken our body's defenses - creating the perfect environment for tumors to form.
But some research suggests that a single, traumatic event might be linked to developing the deadly disease years later.
A bitter divorce, family death or severe injury can create a lasting impression on you, dampening how you respond to stress for the rest of your life and potentially increasing your risk for cancer.
Women who experienced a traumatic event, like a car crash or assault, and had symptoms of PTSD, had a two-fold higher risk for developing ovarian cancer than woman who were not traumatized, a 2019 study of over 54,000 women found.
A 2022 study of 278 patients found that the majority of patients diagnosed with head, neck and pancreatic cancer had dealt with a different, major stressful life event within five years of finding their cancer.
Yet other research has found less conclusive links between cancer and stress. A 2016 study of over 100,000 women in the UK found no link between adverse life events and breast cancer risk.
Studies like these lead Dr Andrea Lynne Roberts that the link between cancer and stress is not very strong, scientifically.
It's true that stressful events which lead to PTSD or lifelong emotional problems can affect your health, and increase your likelihood for developing a host of medical conditions. The link between stress and heart disease, for example, is much stronger than the link to cancer, Dr Roberts said.
'I think if you have high levels of stress, cancer is not the thing you should be worrying about,' she said.
Even with these caveats, scientists have investigated the link between cancer and stress for decades.
It can cause 'a profound impact on how your body’s systems function,' Dr Lorenzo Cohen, the Director of Integrative Medicine Program at MD Anderson said. The best guess that we have is that 'stress makes your body more hospitable to cancer,' Dr Cohen said, meaning that it dampens your bodies natural defenses against cancer and other diseases.Short term stress, which you might have while dealing with errands, before public speaking or preparing to play sports, likely doesn't increase your cancer risk.
Your body can handle brief moments of stress.
However, a one time traumatic event can lead you to develop depression, anxiety or post traumatic stress disorder, all of which could lead to lifetime problems with stress, according to the NIH.
This is called chronic stress. You might have it for a prolonged period of time while in a toxic work environment, processing childhood trauma or dealing with unemployment.
Chronic stress is what doctors think really causes the cellular changes to your body that might eventually lead to cancer, according to Dr Cohen.
This is because when you have this kind of stress, your body produces hormones like cortisol and adrenaline, constantly. This triggers the body's 'natural alarm system' according to Mayo Clinic.
These chemicals make your heart beat faster, raise your blood pressure and increases the amount of sugar in your blood to give you more energy.
They also dampen systems in your body that aren't immediately needed in a fight or flight scenario - reserving the energy that would be used to say, support your immune system to send blood to your muscles, letting you move more quickly.
In short term stress, these effects wear off quickly.
But if you can't calm yourself down over a longer period of time, this can weigh on your body, weakening your immune system, making you depressed and causing digestive problems, Dr Anil Sood a professor of Gynecologic Oncology and Reproductive Medicine at MD Anderson said.
This potentially makes it easier for cancer to grow, both because it increases the risk of diseases like heart disease and diabetes which can lead to cancer, and because the stressed immune system is less ready to fight against cancer.
'Chronic stress also can help cancer grow and spread in a number of ways,' Dr Sood said.
It could be that when someone is stressed out, they're more likely to act in ways that increase their cancer risk - picking up smoking, drinking or foregoing exercise, according to the National Cancer Institute (NCI).
This shouldn't make people dealing with a cancer diagnosis feel guilty, Dr Daniel Bruetman, a medical oncologist at City of Hop Cancer Center in Chicago said.
'They may feel that if they had endured "less stress," they wouldn’t have gotten cancer, or the treatments would have worked,' Dr Bruetman said.
The reality is, the link is unclear, and someone shouldn't feel guilty for their stress - there are lots of other factors that could play a bigger role in your likelihood for developing cancer, like genetics, eating and exercise habits.
In addition, don't think that just because you had a bad day, you're doomed to develop cancer, Nicole Andrews, a registered dietitian who specializes in oncology, said in a TikTok.
'We all have stress in our lives. Please don't think that if you have a stressful day, now you're going to get cancer,' Ms Andrews said.You can do your best, however, to learn how to mange chronic stress, Dr Cohen said.
For some people, this could be as simple as removing a toxic person from their life. But for others, managing stress might involve seeking therapy, practicing meditation, or improving sleep habits, Dr Cohen said.
He's particularly focused on sleep and said that, 'getting eight hours of sleep each night is a great defense against stress.'
