First ever human study validates anti-stress hormone as an indicator for breast cancer risk.

Every person wants to know what he or she can do to lower their risk of breast cancer. Some of the factors associated with breast cancer, such as sex, age or genetics can’t be changed. Other factors such as being overweight, lack of exercise, smoking cigarettes, and/or eating unhealthy food, can be changed by making choices. The medical team would also find it invaluable to gain a biomarker which would warn them if a patient was at risk of breast cancer.  Now, a new study from Lund University shows that women with low levels of an anti-stress hormone have an increased risk of getting breast cancer.

The team state that to their knowledge their study is the first of its kind in humans and confirms previous similar observations from animal experiments.  The new study focused on a hormone which circulates freely in the blood, enkephalin, with pain- and anxiety-reducing properties.   Previous studies show that enkephalin also reinforces the immune system by directly affecting immune cells.

The current study the study was based on blood samples taken from just over 1 900 women in Malmö, the average age of the study participants was 57 years of age. The women were followed up with regard to breast cancer for an average period of 15 years.  The samples were adjusted for age, menopause, hormonal treatment, smoking and other factors which can affect the risk of getting breast cancer.

The data findings showed that among women with the lowest levels of the hormone, the risk of breast cancer was more than three times that of the women with the highest levels of the hormone. This is one of the strongest correlations between cancer risk and a freely circulating biomarker ever described, state the researchers.  The results also confirm a statistical correlation between low enkephalin concentrations in the blood and increased risk of breast cancer, and it remains to be seen whether there is a causal relation showing that a low level of the hormone directly affects tumour development. The researchers note that geographical location and age, in spite of the adjustments in the study, may be significant.

To counteract this, the results were verified by a subsequent control study of a group of 1 500 women with a marginally higher average age. In this group, the results showed that the link between low levels of the hormone and breast cancer was even stronger. Animal studies by other researchers also gave similar indications. The team state that these studies established that enkephalin can reinforce the activity of the immune system against cancer cells, as well as having a direct tumour-inhibiting effect.

The team hope that after further studies the results will facilitate prevention and early detection of breast cancer. They go on to add that for those with an increased risk of breast cancer, potential preventive treatments could take the form of lifestyle interventions to reduce stress and new drugs. The researchers conclude that the findings fit well with the development towards individualised risk assessment and treatment, on the basis of each woman’s needs.

The lab state that their immediate plan is to investigate how to affect the level of enkephalin in healthy individuals. Which they will do in a study with a smaller number of women. They state that they are also interested in the hormone’s role in other cancers.

Source:  Lund University


A breast cancer cell (yellow) under the electron microscope.  Photo: Kristian Pfaller
A breast cancer cell (yellow) under the electron microscope. Photo: Kristian Pfaller

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