Psychological Stress and Cancer: Questions and Answers
Key Points
- Psychological stress affects the body in many ways (see Question 2).
- A direct relationship between psychological stress and the development
of cancer has not been scientifically proven (see Question
3).
- Researchers have suggested that psychological factors may affect
cancer progression (increase in tumor size or spread of cancer in the
body) in patients who have the disease (see Question 5).
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Introduction
The complex relationship between physical and psychological health is not
well understood. Scientists know that psychological stress can affect the
immune system, the body’s defense against infection and disease (including
cancer); however, it is not yet known whether stress increases a person’s
susceptibility to disease (1).
- What is psychological stress?
Psychological stress refers to the emotional and physiological reactions
experienced when an individual confronts a situation in which the demands
go beyond their coping resources. Examples of stressful situations are marital
problems, death of a loved one, abuse, health problems, and financial crises
(2).
- How does stress affect the body?
The body responds to stress by releasing stress hormones,
such as epinephrine
(also called adrenaline) and cortisol (also called hydrocortisone).
The body produces these stress hormones to help a person react to a situation
with more speed and strength. Stress hormones increase blood pressure, heart
rate, and blood sugar levels. Small amounts of stress are believed to be
beneficial, but chronic (persisting or progressing over a long period of
time) high levels of stress are thought to be harmful (1).
Stress that is chronic can increase the risk of obesity,
heart disease, depression,
and various other illnesses. Stress also can lead to unhealthy behaviors,
such as overeating, smoking, or abusing drugs
or alcohol, that may affect cancer risk.
- Can stress increase a person’s risk of developing
cancer?
Studies done over the past 30 years that examined the relationship between
psychological factors, including stress, and cancer risk have produced conflicting
results. Although the results of some studies have indicated a link between
various psychological factors and an increased risk of developing cancer,
a direct cause-and-effect relationship has not been proven (3,
4).
Some studies have indicated an indirect relationship between stress and
certain types of virus-related
tumors. Evidence from both animal and human studies suggests that chronic
stress weakens a person’s immune
system, which in turn may affect the incidence
of virus-associated cancers, such as Kaposi sarcoma
and some lymphomas
(5).
More recent research with animal
models (animals with a disease that is similar to or the same as a disease
in humans) suggests that the body’s neuroendocrine
response (release of hormones into the blood in response to stimulation
of the nervous system) can directly alter important processes in cells
that help protect against the formation of cancer, such as DNA
repair and the regulation of cell growth (6).
- Why are the study results inconsistent?
It is difficult to separate stress from other physical or emotional factors
when examining cancer risk (3, 4). For
example, certain behaviors, such as smoking and using alcohol, and biological
factors, such as growing older, becoming overweight,
and having a family history of cancer, are common risk
factors for cancer. Researchers may have difficulty controlling the
presence of these factors in the study group or separating the effects of
stress from the effects of these other factors (3). In
some cases, the number of people in the study, length of follow-up,
or analysis
used is insufficient to rule out the role of chance (4).
Also, studies may not always take into account that cancer is not a homogeneous
(uniform in nature) disease.
- How does stress affect people who have cancer?
Studies have indicated that stress can affect tumor growth and spread,
but the precise biological mechanisms underlying these effects are not well
understood. Scientists have suggested that the effects of stress on the
immune system may in turn affect the growth of some tumors (7).
However, recent research using animal models indicates that the body’s
release of stress hormones can affect cancer cell functions directly (8).
A review of studies that evaluated psychological factors and outcome in
cancer patients suggests an association between certain psychological factors,
such as feeling helpless or suppressing negative emotions, and the growth
or spread of cancer, although this relationship was not consistently seen
in all studies (3). In general, stronger relationships
have been found between psychological factors and cancer growth and spread
than between psychological factors and cancer development (6).
- Where can a person find more information about psychological
stress?
Additional information about stress can be found on the National Institute
of Mental Health’s (NIMH) Web site at http://www.nimh.nih.gov
on the Internet. The NIMH, a part of the National
Institutes of Health, provides national leadership in the study of mental
and behavioral disorders,
including the causes and effects of psychological stress.
The National Women’s Health Information Center (NWHIC), a service
of the Office on Women’s Health, provides information on stress and
health on its Web site at http://www.womenshealth.gov
on the Internet. In particular, the fact sheet Stress and Your Health
provides answers to frequently asked questions about causes of stress, how
women react to stress, and ways to handle stress. This resource is available
at http://www.womenshealth.gov/faq/stress.htm
on the Internet.
Selected References
- Segerstrom S, Miller G. Psychological stress and the
human immune system: A meta-analytic study of 30 years of inquiry. Psychological
Bulletin 2004; 130(4): 601–630.
- Venes D, Thomas C, editors. Taber's Cyclopedic
Medical Dictionary. 19th ed. Philadelphia: FA Davis Company, 2001.
- Garssen B. Psychological factors and cancer development:
Evidence after 30 years of research. Clinical Psychology Review 2004;
24(3):315–338.
- Dalton SO, Boesen EH, Ross L, Schapiro IR, Johansen
C. Mind and cancer: Do psychological factors cause cancer? European Journal
of Cancer 2002; 38(10): 1313–1323.
- Reiche EM, Nunes SO, Morimoto HK. Stress, depression,
the immune system, and cancer. The Lancet Oncology 2004; 5(10):617–625.
- Antoni MH, Lutgendorf SK, Cole SW, et al. The influence
of bio-behavioural factors on tumour biology: Pathways and mechanisms. Nature
Reviews Cancer 2006; 6(3):240–248.
- Andersen BL, Farrar WB, Golden-Kreutz D, et al. Stress
and immune responses after surgical treatment for regional breast cancer.
Journal of the National Cancer Institute 1998; 90(1):30–36.
- Thaker PH, Han LY, Kamat AA, et al. Chronic stress
promotes tumor growth and angiogenesis in a mouse model of ovarian carcinoma.
Nature Medicine 2006; 12(8):939–944.
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