Engaging in physical activity for at least one hour daily reduces breast cancer risk by 12 percent in women of all ages, a new study finds.

Breast cancer is the most common cancer among women globally. According to recent predictions, approximately 232,340 new cases of invasive breast cancer will be diagnosed in women in 2014 and about 39,620 women will die from the disease.

Researchers of a new study found that practicing sports or exercising for at least one hour daily reduced breast cancer risk by 12 percent in women of all ages, irrespective of their weight and geographical location. For the study, the researchers conducted an analysis of 37 studies published between 1987 and 2013, representing over four million women

"These are all the studies looking at the relationship between physical exercise and breast cancer risk that have been published to date, so we are confident that the results of our analysis are robust," Professor Mathieu Boniol, Research Director at the International Prevention Research Institute, said in a press statement.

Benefits and results of exercising largely depend on the tumor type but physical activities did help to a large extent. However, the benefits of exercising didn't apply to women taking hormone replacement therapy (HRT). Fortunately, the increased awareness of the side effects of HRT has led to a decrease in the number of women using this therapy and this means that the beneficial effects of exercising will most likely grow in the years to come.

"Adding breast cancer, including its aggressive types, to the list of diseases that can be prevented by physical activity should encourage the development of cities that foster sport by becoming bike and walk-friendly, the creation of new sports facilities, and the promotion of exercise through education campaigns," said Prof Boniol. "This is a low cost, simple strategy to reduce the risk of a disease that currently has a very high cost, both to healthcare systems and to patients and their families. It is good news both for individuals and for policy makers."

Another study conducted in October last year found that women who reported walking to be their only form of physical activity and walked for at least 7 hours per week experienced a 14 percent lower risk of breast cancer compared to women who walked for only 3 hours or less per week. However, women who reported walking 7 hours per week along with doing other vigorous exercises experienced a 25 percent lower risk of breast cancer.

"Our results clearly support an association between physical activity and postmenopausal breast cancer, with more vigorous activity having a stronger effect," said Alpa Patel, PhD, leader of the study and American Cancer Society strategic director of Cancer Prevention Study-3. "Our findings are particularly relevant, as people struggle with conflicting information about how much activity they need to stay healthy. Without any other recreational physical activities, walking on average of at least one hour per day was associated with a modestly lower risk of breast cancer. More strenuous and longer activities lowered the risk even more."

Researchers also found that women benefitted from walking irrespective of them being overweight, normal weight or obese. Walking helped reduce the risk of breast cancer whether or not women were taking menopausal hormone therapy. Mild physical activities including walking and exercising was found to reduce the risk of both estrogen receptor positive and estrogen receptor negative cancers.

According to the latest Physical Activity Guideline for Americans report, experts recommend at least 150 minutes of moderate to vigorous physical activity (MVPA) per week. This doesn't only lower the risk of breast cancer but also keeps the body fit and healthy. Each session could be an accumulation of eight to 10 minutes.  MVPA is defined as greater than 2,020 counts per minute measured with a tool called an accelerometer, which translates to a walking speed of 3 km per hour.

The new study was presented to the 9th European Breast Cancer Conference (EBCC-9).