FOR those women who are still not convinced of the usefulness of physical
activity, here is another reason to put on
the track suit. A recently published
report of a study conducted on more
than 25r,000 women in Norway suggests
that, compared to sedentary women,
those who exercised regularly had a
lower risk.of developing breast cancer.
Moreover, the chances of developing
breast cancer recede in direct proportion to the time spent on the exercise
floor (New England Journal of Medicine,
Vol 336j No 18).
A team led by Inger Thune at the
Institute of Community Medicine,
University of Trom1p, Norway, and the
Cancer Registry of Norway studied
25,624 healthy women aged 20-54 years
over the decade ending 1983. Their
objective was to correlate physical activity during leisure time and at work to the risk of developing breast cancer.
Most cases of breast cancer are related to lifestyle and environment in a way that is not clear to researchers and scientists. Data relating to their physical activity, diet, age of menstruation, number of children and age at which they had their first child was recorded. The
risk of breast cancer increases in women
who start menstruating early, have their
first child after the age of 30, and are
overweight. Excess dietary fat has also
been linked to breast cancer in the past.
Researchers followed the women for
an average of 14 years, updating the
information gathered halfway during
the study period. As Norway keeps a
country-wide register on all patients
diagnosed to have cancer, it was easy for
the researchers to determine which of
the participating women in their study
developed breast cancer. It was found
that 351 women developed the cancer.
When researchers analysed the data,
they found that exercise patterns predicted breast cancer risk independently
of other factors. Those who exercised at
least four hours a week during their
leisure time had a 37 per cent lower risk
of developing breast cancer. This effect
was far stronger in those women. who
had not reached menopause.
One of the hypotheses that seeks to
explain the effect was proposed by Leslie
Bernstein, a leading researcher from the
University of Southern California, US.
Bernstein says that physical exercise
reduces the exposure of women to
oestrogen. The presumption is that
exposure to oestrogen increases the risk
of developing breast cancer. This may
explain why women who start menstruating early are at a greater risk, as they are exposed to the hormone for longer
With the availability -of more information about breast cancer genes BRCA and BRCA2 and the associated publicity
about genetic screening and its efficacy,
many women had become convinced
that prevention of breast cancer was
beyond them. The study provides hope
to such women.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.