Psychological Stress and Cancer: Questions and Answers

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).

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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Related NCI materials and Web pages:
National Cancer Institute Fact Sheet 10.3, Quitting Tobacco: Handling Stress ... Without Smoking 1(http://www.cancer.gov/cancertopics/factsheet/Tobacco/stress)
Understanding Cancer Series: The Immune System 2(http://www.cancer.gov/cancertopics/understandingcancer/immunesystem)
What You Need To Know About™ Cancer 3(http://www.cancer.gov/cancertopics/wyntk/overview)
For more help, contact:
NCI's Cancer Information Service Telephone (toll-free): 1–800–4–CANCER (1–800–422–6237) TTY (toll-free): 1–800–332–8615 LiveHelp® online chat: https://cissecure.nci.nih.gov/livehelp/welcome.asp

Glossary Termsanalysis
A process in which anything complex is separated into simple or less complex parts. animal model
An animal with a disease either the same as or like a disease in humans. Animal models are used to study the development and progression of diseases and to test new treatments before they are given to humans. Animals with transplanted human cancers or other tissues are called xenograft models. biological

Pertaining to biology or to life and living things. In medicine, refers to a substance made from a living organism or its products. Biologicals may be used to prevent, diagnose, treat or relieve of symptoms of a disease. For example, antibodies, interleukins, and vaccines are biologicals. Biological also refers to parents and children who are related by blood. cancer (KAN-ser)
A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. cell (sel)

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells. depression
A mental condition marked by ongoing feelings of sadness, despair, loss of energy, and difficulty dealing with normal daily life. Other symptoms of depression include feelings of worthlessness and hopelessness, loss of pleasure in activities, changes in eating or sleeping habits, and thoughts of death or suicide. Depression can affect anyone, and can be successfully treated. Depression affects 15-25% of cancer patients. disorder (dis-OR-der)
In medicine, a disturbance of normal functioning of the mind or body. Disorders may be caused by genetic factors, disease, or trauma. DNA
The molecules inside cells that carry genetic information and pass it from one generation to the next. Also called deoxyribonucleic acid. drug
Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic. epinephrine
A hormone and neurotransmitter. Also called adrenaline. follow-up
Monitoring a person's health over time after treatment. This includes keeping track of the health of people who participate in a clinical study or clinical trial for a period of time, both during the study and after the study ends. hormone (HOR-mone)
One of many chemicals made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be made in the laboratory. hydrocortisone
A drug used to relieve the symptoms of certain hormone shortages and to suppress an immune response. immune system (ih-MYOON SIS-tem)
The complex group of organs and cells that defends the body against infections and other diseases. incidence

The number of new cases of a disease diagnosed each year. lymphoma (lim-FOH-muh) Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells.

Non-Hodgkin lymphomas can be further divided into cancers that have an indolent (slow-growing) course and those that have an aggressive (fast-growing) course. These subtypes behave and respond to treatment differently. Both Hodgkin and non-Hodgkin lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer. National Institutes of Health

A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the National Institutes of Health Web site at http://www.nih.gov. Also called NIH. neuroendocrine (NOOR-oh-EN-doh-krin)
Having to do with the interactions between the nervous system and the endocrine system. Neuroendocrine describes certain cells that release hormones into the blood in response to stimulation of the nervous system. obese

Having an abnormally high, unhealthy amount of body fat. overweight
Being too heavy for one’s height. Excess body weight can come from fat, muscle, bone, and/or water retention. Being overweight does not always mean being obese. progression (proh-GREH-shun)
In medicine, the course of a disease, such as cancer, as it becomes worse or spreads in the body. risk factor

Something that may increase the chance of developing a disease. Some examples of risk factors for cancer include age, a family history of certain cancers, use of tobacco products, certain eating habits, obesity, lack of exercise, exposure to radiation or other cancer-causing agents, and certain genetic changes. sarcoma

A cancer of the bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. tumor (TOO-mer)
An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancerous), or malignant (cancerous). Also called neoplasm. virus (VY-rus)
In medicine, a very simple microorganism that infects cells and may cause disease. Because viruses can multiply only inside infected cells, they are not considered to be alive.

Table of Links
1.http://www.cancer.gov/cancertopics/factsheet/Tobacco/stress
2 http://www.cancer.gov/cancertopics/understandingcancer/immunesystem
3 http://www.cancer.gov/cancertopics/wyntk/overview