Contact: Dr. Sibylle Kohlstädt
[email protected]
Helmholtz Association of German Research Centres
Reduced breast cancer risk: Physical activity after menopause pays off
Several studies had previously
suggested that regular physical exercise reduces the breast cancer risk
of women. However, it had been unknowned just how much exercise women
should take in which period in life in order to benefit from this
protective effect. Moreover, little was known about which particular
type of breast cancer is influenced by physical activity.
Answers
to these questions are now provided by the results of the MARIE study,
in which 3,464 breast cancer patients and 6,657 healthy women between
the ages of 50 and 74 years were questioned in order to explore the
connections between life style and breast cancer risk. Participants of
the study, which was headed by Professor Dr. Jenny Chang-Claude and
conducted at the German Cancer Research Center and the University
Hospitals of Hamburg-Eppendorf, were questioned about their physical
activity during two periods in life: from 30 to 49 years of age and
after 50.
A comparison between control subjects and breast
cancer patients showed that women in the control group had been
physically more active than patients. The scientists calculated the
relative breast cancer risks taking account of the effect of other risk
factors. Results show that the risk of developing breast cancer after
menopause was lower by about one third in the physically most active
MARIE participants compared to women who had generally taken little
physical exercise.
For this reduced risk it is not necessary
to work out hard at the gym. The women in the physically most active
group, for example, walked for two hours every day and cycled for one
hour, while the most inactive study participants walked for only about
30 minutes every day. The epidemiologists also discovered that physical
activity in the postmenopausal period is particularly beneficial for
reducing breast cancer risk.
A closer look at the types of
breast cancer revealed that physically active women are less frequently
affected, in particular, by tumors that form receptors for the two
female sexual hormones, estrogen and progesterone. These malignant
'hormone receptor positive tumors' accounted for 62.5 percent of breast
cancers among MARIE participants. Other tumor markers, such as HER2
receptor formation or differentiation stage of cancer cells, were found
to be unrelated to physical activity.
The effect of physical
activity was independent of weight gain, total energy intake or body
mass index. Therefore, researchers assume that physical exercise
reduces the risk of cancer through hormonal mechanisms instead merely
by a reduction of body fat or other changes in physical constitution,
as it has often been assumed.
"It doesn't always have to be
sports," says Associate Professor Dr. Karen Steindorf of DKFZ, who has
headed this analysis. "In our calculations we have also taken account
of activities such as gardening, cycling or walking to the shops. Our
advice to all women is therefore to stay or become physically active
also in the second half of your life. You will not only reduce your
risk of breast cancer, but it has been proven that your bones, heart
and brain also benefit from it."
###
Martina
E. Schmidt, Karen Steindorf, Elke Mutschelknauss, Tracy Slanger, Silke
Kropp, Nadia Obi, Dieter Flesch-Janys and Jenny Chang-Claude: Physical
Activity and Postmenopausal Breast Cancer: Effect Modification by
Breast Cancer Subtypes and Effective Periods in Life.
Cancer Epidemiology Biomarkers and Prevention 2008, DOI: 10.1158/1055-9965.EPI-08-0479
The
German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ)
is the largest biomedical research institute in Germany and is a member
of the Helmholtz Association of National Research Centers. More than
2,000 staff members, including 850 scientists, are investigating the
mechanisms of cancer and are working to identify cancer risk factors.
They provide the foundations for developing novel approaches in the
prevention, diagnosis, and treatment of cancer. In addition, the staff
of the Cancer Information Service (KID) offers information about the
widespread disease of cancer for patients, their families, and the
general public. The Center is funded by the German Federal Ministry of
Education and Research (90%) and the State of Baden-Württemberg (10%).