Stress May Reduce Women

Stress May Reduce Women's Risk of Breast Cancer

It might limit production of estrogen, study suggests

By Amanda Gardner
HealthDay Reporter

THURSDAY, Sept. 8 (HealthDay News) -- Here's news that could ease worries about breast cancer: Women with higher levels of daily stress showed a lower risk of developing the disease, according to new research.

But that's no reason to increase your stress levels, said the study authors.

"Even though we find a lower risk of breast cancer among stressed women, let me just emphasize that stress cannot be considered a healthy response," said study lead author Naja Rod Nielsen, a research assistant at the National Institute of Public Health in Copenhagen, Denmark.

"Stress is not a desirable state and it may lead to the development of other disease, particularly cardiovascular disease," Nielsen said.

So what does this information potentially contribute?

"Stress is a large problem, especially in the westernized world, and this study may help us understand some of the mechanisms behind breast cancer and how stress actually affects breast-cancer risk," Nielsen said. "Further, some women may partly blame their own stressful lifestyle when diagnosed with breast cancer. Hopefully, this and other studies may counteract such reactions."

The study findings appear in the Sept. 10 issue of the British Medical Journal.

Other experts, however, urged caution when interpreting the results.

"It's certainly not firm. The findings are based on small numbers. It's borderline statistically significant and they haven't given any good biological correlate to what the measure shows," said Heather Spencer Feigelson, a senior epidemiologist with the American Cancer Society. But "it suggests that stress doesn't cause breast cancer and that's probably true."

While some researchers have studied the effect of acute stress -- such as the death of a family member -- on breast cancer, less attention has been paid to the impact of routine daily stress.

The researchers examined data on 6,689 women participating in the Copenhagen City heart study. At the beginning of the study (1981-83), participants were asked about their levels of routine, daily stress -- defined as anxiety, impatience, nervousness, sleeplessness or tension. The women were followed until 1999.

During the 18 years of follow-up, 251 of the participants were diagnosed with breast cancer. Women reporting high levels of stress were 40 percent less likely to develop breast cancer than women reporting low levels, the researchers report.

For each increase in stress level on a six-point scale, women were 8 percent less likely to develop breast cancer. The association was more pronounced in women receiving hormone therapy, the study found.

What might explain the findings? The researchers speculate that stress activates stress hormones which may, in turn, limit the body's production of estrogen, a well-known risk factor for breast cancer.

Hormone-sensitive women (such as those taking hormone therapy) are more likely to be susceptible to stress-induced changes in estrogen, which could explain why the association was more dramatic in this group, the authors said.

This explanation does seem to back up another recent study that found that seaweed may help protect against breast cancer. Kelp seaweed may reduce the amounts of estrogen circulating in the body, the study suggested.

Still, all of this is just hypothetical, the authors of the new study cautioned.

"The mechanisms behind the observed lower risk of breast cancer among stressed women remain unknown," Nielsen said. "One hypothesis is that prolonged activation of stress hormones can lead to lower production of estrogens, which is a main risk factor for breast cancer. This hypothesis is only based on experimental data and remains to be confirmed in humans.

"It would be an obvious next step in this line of research to address the validity of this hypothesis in humans, and it is something we are currently working at. It would also be very interesting to see if these findings can be replicated in other studies," Nielsen said.

More information

To learn more about preventing breast cancer, visit the National Cancer Institute.

SOURCES: Naja Rod Nielsen, Ph.D. candidate and research assistant, National Institute of Public Health, Copenhagen, Denmark; Heather Spencer Feigelson, senior epidemiologist, American Cancer Society, Atlanta; Sept. 10, 2005, British Medical Journal

Daily stress stops breast cancer

High levels of daily stress may lower a woman's risk of breast cancer, researchers believe.

The findings contrast to past work suggesting stress doubles the risk.

The Danish team says it may be that regular doses of stress are good, while a short burst of acute stress, around a life event such as bereavement, is bad.

Their work in the British Medical Journal is based on survey responses of nearly 7,000 women living in Copenhagen between 1981 and 1983.

Experts said the research did not clear up whether or not stress is an important factor in breast cancer risk.

At the start of the study, the researchers asked the women what levels of stress they experienced routinely in their lives, and classified the results into low, medium and high levels.

Stress was defined as tension, nervousness, impatience, anxiety, or sleeplessness.

The researchers then tracked whether any of the women developed breast cancer over the next 18 years - 251 of them did.

The study authors worked out that women reporting high levels of stress were 40% less likely to develop breast cancer than women reporting low levels of stress.

For every increased level of stress on a six-level scale, women were 8% less likely to develop breast cancer.

Dr Naja Nielsen and colleagues suggest one explanation for the findings may be that sustained levels of high stress may affect levels of the female hormone oestrogen, which over time may have an influence on developing breast cancer.

But they cautioned that this theory has not been tested, and research in this area so far has mainly been restricted to animals.

They also warned that stress-induced changes in hormonal balances are not a healthy response, and continued stress may play a damaging part in other illnesses, particularly heart disease.

Work published in the same medical journal in 2002 by a team from Cancer Research UK's London Psychosocial Group found emotional stress did not increase the chance that a breast tumour would return after treatment.

Dr Emma Pennery from Breast Cancer Care said: "We know from talking to women with breast cancer that some of them believe stress to be a contributory factor.

"This new study is therefore very interesting. However, studies have generally produced conflicting results in this area and excessive, prolonged levels of stress can contribute to other health problems and might also be difficult to avoid.

"This study serves as a reminder that we still know very little about the causes of breast cancer and it is likely several factors combine to increase an individual's risk.

"What we do know is that the risk increases with age and that for all women it is important to be breast aware throughout their lives."

Dr Sarah Rawlings of Breakthrough Breast Cancer said: "It's always hard to measure the impact of stress on breast cancer risk as it's difficult to untangle from other factors in our lives and everyone views their own stress levels differently.

"This study doesn't help us to draw further conclusions. However, maintaining a healthy balanced lifestyle is important - we know that high stress levels can lead to unhealthy behaviour, which may alter your risk of breast cancer and other diseases."

Source: BBC News Online, 08/09/2005

Back to News