我同意老狼的說法~~

原文來源：National Cancer Institute

http://www.cancer.gov/cancertopics/factsheet/Risk/stress

Psychological Stress and Cancer

1. How does the body respond during stress?

    

   The body responds to physical, mental, or emotional pressure by releasing stress hormones (such as epinephrine and norepinephrine) that increase blood pressure, speed heart rate, and raise blood sugar levels. These changes help a person act with greater strength and speed to escape a perceived threat.

   Research has shown that people who experience intense and long-term (i.e., chronic) stress can have digestive problems, fertility problems, urinary problems, and a weakened immune system. People who experience chronic stress are also more prone to viral infections such as the flu or common cold and to have headaches, sleep trouble, depression, and anxiety.

    

2. Can psychological stress cause cancer?

    

   Although stress can cause a number of physical health problems, the evidence that it can cause cancer is weak. Some studies have indicated a link between various psychological factors and an increased risk of developing cancer, but others have not.

   Apparent links between psychological stress and cancer could arise in several ways. For example, people under stress may develop certain behaviors, such as smoking, overeating, or drinking alcohol, which increase a person’s risk for cancer. Or someone who has a relative with cancer may have a higher risk for cancer because of a shared inherited risk factor, not because of the stress induced by the family member’s diagnosis.

    

3. How does psychological stress affect people who have cancer?

    

   People who have cancer may find the physical, emotional, and social effects of the disease to be stressful. Those who attempt to manage their stress with risky behaviors such as smoking or drinking alcohol or who become more sedentary may have a poorer quality of life after cancer treatment. In contrast, people who are able to use effective coping strategies to deal with stress, such as relaxation and stress management techniques, have been shown to have lower levels of depression, anxiety, and symptoms related to the cancer and its treatment. However, there is no evidence that successful management of psychological stress improves cancer survival.

   Evidence from experimental studies does suggest that psychological stress can affect a tumor’s ability to grow and spread. 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 spread (metastasize). In one set of experiments, tumors transplanted into the mammary fat pads of mice had much higher rates of spread to the lungs and lymph nodes if the mice were chronically stressed than if the mice were not stressed. Studies in mice and in human cancer cells grown in the laboratory have found that the stress hormone norepinephrine, part of the body’s fight-or-flight response system, may promote angiogenesis and metastasis.

   In another study, women with triple-negative breast cancer who had been treated with neoadjuvant chemotherapy were asked about their use of beta blockers, which are medications that interfere with certain stress hormones, before and during chemotherapy. Women who reported using beta blockers had a better chance of surviving their cancer treatment without a relapse than women who did not report beta blocker use. There was no difference between the groups, however, in terms of overall survival.

   Although there is still no strong evidence that stress directly affects cancer outcomes, some data do suggest that patients can develop a sense of helplessness or hopelessness when stress becomes overwhelming. This response is associated with higher rates of death, although the mechanism for this outcome is unclear. It may be that people who feel helpless or hopeless do not seek treatment when they become ill, give up prematurely on or fail to adhere to potentially helpful therapy, engage in risky behaviors such as drug use, or do not maintain a healthy lifestyle, resulting in premature death.

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• 很好的內容！謝謝！ -TBz- ♂ (0 bytes) () 01/23/2013 postreply 14:38:54