WOMENS HEALTH: PHYSICAL ACTIVITY AND BREAST CANCER
Epidemiology
Twenty-three of 35 studies conducted to date show a decreased risk in breast Cancer in women who are physically active. The greatest risk reductions occurred in those going from a sedentary lifestyle to moderate-intensity physical activity.
Observations from 26 of 41 studies including 108,000 breast cancer cases demonstrated that both occupational physical activity and leisure-time physical activity were associated with a 30% reduction in breast cancer risk in pre-, peri-, and postmenopausal women, with a graded dose-response relationship reported in 16 of 28 studies. Differences in study outcomes could be due to a variable association between physical activity and breast cancer across the lifespan and hormonal status of the women.
Lee et al analyzed nearly 40,000 women and concluded that physical inactivity may increase the risk of all breast cancer only in postmenopausal women. Postmenopausal women who walked at least 2 miles per day experienced a risk reduction of 33% compared with those walking only a quarter mile per day. This relationship did not hold in postmenopausal women with breast cancers positive for estrogen or progesterone receptors. But in a specific subcategory of women, a 33% reduction in breast cancer was found.
Breast cancer has multiple causes. It is interesting to consider that if physical inactivity accentuates only one of these causes, study outcomes will differ. This may explain the varying results often obtained.
Biochemical/Cellular Mechanisms
Some aspects of sex and metabolic hormone patterns throughout life are likely responsible for a large number of breast cancer occurrences. As physical activity modulates these sex and metabolic hormone patterns, it is possible that physical activity-induced adaptations play some role in the breast cancer-physical activity association. The underlying biochemical/cellular processes by which physical activity may alter mechanisms and decrease the risk of breast cancer are largely unknown.
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WOMENS HEALTH
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PUBERTY
All of a sudden, strange things start to happen to our young Miss as she begins to grow up.
It can commence anywhere from nine years of age onwards. In recent years, for reasons unknown, it seems to be commencing at a younger and younger age in western lands. No doubt it is tied up with today's sophisticated way of living, earlier psychological development and earlier mental stimulation, all of which play a potent part. It is referred to as puberty.
Suddenly the system starts to develop potent chemicals, called sex hormones, and these have a rapid and far-reaching effect on many parts of the system.
Suddenly breast development commences. The unnoticed, flat, pinkish nipples become more marked, rounded and protrude as they rapidly increase in size. This is most noticeable between the ages of 8 and 15. Pubic hair commences to grow, this becoming obvious in the 8-14 age group at any time. Underarm hair also makes an appearance.
Menstrual periods make a tentative start, and anywhere from 10 to 161?2 years they will become more and more regular. There is usually a dramatic increase in height; this is called a 'height spurt' and takes place in the 9-141?2 age bracket.
The skinny, school-age child is transformed within a few short years into a modern young woman of vastly different appearance and shape. Most tend to put on weight, but there is an alteration of the system's fat deposits, giving the body the characteristic female curves which tend to remain for life. In brief, Nature has transformed her into an adult, with the physical and psychological issues that this involves.
But although the ages quoted are 'averages', the range is enormous and varied. Many develop sexually at an early age. Others are late developers, and often they may reach the age of 18 or 20 before some of the typical secondary sexual characteristics (as the doctors say) have appeared. This is especially so in regard to breast development.
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Womens health
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