Exercise May Lower Breast Cancer Risk by Changing Estrogen Metabolism

A message from Staness

About 1 in 8 women will develop invasive breast cancer over the course of her lifetime.  For women in the US, breast cancer death rates are higher than those for any other cancer, besides lung cancer.

The most significant risk factor for breast cancer are your sex and age.

Take action, read this insightful article provided by BreastCancer.org and start exercising today! Great chart of aerobic activities below.


Many studies have shown a link between exercise and a lower risk of breast cancer, but the reason why hasn’t been clear. Now new research is starting to provide an answer by showing that aerobic exercise seems to change how our bodies break down estrogen. It’s the first study to show that aerobic exercise has a direct impact on estrogen metabolism in premenopausal women.

The study was published in the May 2013 issue of the journal Cancer Epidemiology, Biomarkers & Prevention. Read the abstract of “The Effects of Aerobic Exercise on Estrogen Metabolism in Healthy Premenopausal Women.”

The researchers wanted to find out whether exercise affects the body’s production of compounds produced when estrogen is broken down. These compounds are called estrogen metabolites. Earlier research has suggested that a higher ratio of certain “good” estrogen metabolites to certain “bad” estrogen metabolites was linked to lower breast cancer risk. The “good” metabolite is called 2-hydroxyestrone (2-OHE1) and the “bad” metabolite is called 16alpha-hydroxyestrone (16alpha-OHE1). 2-OHE1 can reduce the effects of estradiol, a type of estrogen that’s been linked to breast cancer development. 16alpha-OHE1 can contribute to cell processes that could lead to the development of breast cancer.

The researchers randomly assigned 391 inactive, healthy, young, premenopausal women to either a non-exercising control group or an exercise intervention group. The women were between 18 and 30 years old and ranged in weight from healthy to obese.

The women in the control group continued an inactive lifestyle for the 16-week study period. The women in the intervention group did 30 minutes of moderate-to-vigorous aerobic exercise five times a week during the 16 weeks. The intensity of the workouts was adjusted for each woman so they all had similar maximum heart rates.

For 3 days before the study started and 3 days after it ended, the researchers measured the amount of certain estrogen metabolites in the women’s urine.

At the end of the study, the women in the exercise group had higher levels of 2-OHE1 (“good” estrogen metabolites) and lower levels of 16alpha-OHE1 (“bad” estrogen metabolites). This means the ratio of 2-OHE1 to 16alpha-OHE1 was higher in women who exercised. This ratio increase didn’t happen in women in the inactive group.

There were no other differences in other estrogen metabolites or ratios in either group.

Over the course of the study, the women in the exercise group also became more aerobically fit, gained more lean body mass, and lost body fat.

Based on the results, the researchers concluded that the effect exercise has on estrogen metabolism may be one explanation of how exercise reduces breast cancer risk.

Keep in mind that we don’t know the exact ideal amount or intensity of exercise to reduce breast cancer risk. The American Cancer Society and many doctors recommend that women who’ve been diagnosed with breast cancer exercise regularly — about 4 to 5 hours per week at a moderate intensity level.

Along with healthy diet and lifestyle choices, regularly doing moderately intense exercise is one the best steps all women can take to help keep breast cancer risk as low as it can be. Regular exercise also helps keep your general health the best that it can be. No matter how old you are, it’s never too soon or too late to get moving.

Visit the Breastcancer.org  Exercise pages for tips on exercising safely and how to stick to an exercise routine.

Published on May 23, 2013 at 4:03 am. Last modified on May 24, 2013 at 3:02 pm

Aerobic Exercise

Aerobic exercise uses the large muscles in your body in rhythmic, repetitive motions. See the chart below for some examples.

Benefits: Aerobic exercise makes your heart, lungs, blood vessels, and muscles work more efficiently, increasing your stamina and endurance. It also boosts your mood, helps you sleep better, and reduces your stress. It can also reduce your risk of breast cancer coming back (recurrence), as well as reduce the risks of heart disease, diabetes, and osteoporosis.

Type of Aerobic Exercise Equipment You Need Where You Can Do It
Walking walking shoes, comfortable clothing just about anywhere (sidewalk, track, mall, treadmill)
Running/jogging running shoes, comfortable shorts or running pants, comfortable shirt, sports bra inside on a treadmill, outside on running paths, trails, sidewalks (watch out for pedestrians, bikes, and cars), or a track
Bike riding bicycle, comfortable clothing, helmet outside, on bike trails or bike lanes; check your local ordinances about riding a bike on sidewalks
Elliptical machine*/stair stepper elliptical or stair stepper machine, comfortable clothing inside your home if you own a machine, at a gym if you don’t
Dancing (Zumba, belly dancing, flamenco, tap, ballet, square dancing, ballroom dancing, etc.) comfortable clothing; certain types of dance (flamenco or ballet, for example) require special shoes in your home if you have a large, empty room; at a dance studio, gym, or classroom
Skiing skis, poles, boots, helmet, hat, goggles, insulated jacket and pants or bibs, gloves, and socks cross-country skiing* can be done at parks or ski resorts; downhill skiing is usually done at a ski resort
Skating ice or roller skates or roller blades, socks, comfortable clothing, wrist and elbow guards, helmet roller skating and roller blading can be done on jogging paths and sidewalks; ice skating can be done on indoor or outdoor rinks
Tennis* racquet, balls, comfortable clothing, court shoes indoor or outdoor tennis court
Swimming bathing suit and towel; goggles and swim cap may be required at certain pools public or private pools; certain public lakes allow swimming
Aerobics comfortable clothing, court shoes various types of aerobics classes are offered at many gyms; you can also move along to a DVD at home
Rowing* comfortable clothing, a shell and oars if you’re rowing outside, a rowing machine if you’re rowing inside outside on a river or lake, inside on a rowing machine at the gym or your home
Hiking hiking boots or shoes, socks, comfortable clothing appropriate for the weather, water bottles; a hat, pack, sunglasses, insect repellent, and first-aid kit; hiking poles are optional outside at public and national parks
Basketball court shoes, comfortable clothing, basketball, hoop inside at a gym or school with a court, outside on courts, or anywhere with a hoop
Golf clubs, bag, shoes, balls, tees, comfortable clothing (you may be able to rent clubs and a bag at certain golf courses) outside at public or private golf course
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