Cancer is one of the leading causes of disability and death for adults over age 44, according to Healthy People 2020, and a significant portion of those under that relatively young age. In fact, cancer diagnoses in all age groups have been steadily increasing for the past three decades. This may be partially because there is better diagnostic ability now, and that people were dying of illnesses before this that were cancer but were not recognized to be cancer. That’s a possibility, but scientists believe the incidence is steadily increasing. Some of that may be due to societal factors than can be altered, such as chemicals in food and pollutants in the air, as well as habits such as smoking marijuana or cigarettes and the consumption of alcohol.
Another surprising “modifiable” risk factor is being overweight. Most people know being overweight or obese is hard on the heart and lungs, but many are surprised to find that having an elevated BMI is a risk for cancer. It statistically raises the risk for certain cancers more than others — liver cancer and gastric cancer are two that obesity may increase the risk of, while it has a negligible role in the development of skin cancer called malignant melanoma. However, there is a correlation between exercise and the decreased risk development of over a dozen types of cancers, and the researchers believe it is due to a reduced body mass index, according to Live Science. However, there are small segments of the population for which the BMI is not accurate or indicative of a healthy weight: Body builders or those with extreme muscle mass. For most of the population, the body mass index is still considered accurate. Anyone with a BMI over 30 is considered obese, researchers say, and regular exercise is the number one combatant of obesity, winning out even over low-fat dieting.
This was a scientifically rigorous study, meaning it had a large number of participants over a long time, so the results are likely to be more accurate than smaller or shorter studies. Researchers extracted data from 1.4 million people in the United States and Europe, which have similar dietary habits and access to healthcare. The subjects were in 12 different study groups and were followed for about 11 years and during that time, 186,000 cases of cancer were diagnosed in the study participants. Researchers also asked people about their exercise activities, such as walking, running, swimming and how vigorous these activities were.
In general, the participants who regularly exercised had a lowered risk of cancer, around seven percent lower than the rest of the population. However, certain types of cancer were found to be significantly lower in the population of exercisers. This is good news because for most people, moderate types of activity are possible. The types of cancer that were lowered are the following.
- Esophageal cancer, risk lowered by 42 percent
- Liver cancer, risk lowered by 27 percent
- Lung cancer, risk lowered by 26 percent
- Kidney cancer, risk lowered by 23 percent
- Stomach cancer of the cardia (top portion of the stomach), risk lowered by 22 percent
- Endometrial cancer, risk lowered by 21 percent
- Myeloid leukemia, risk lowered by 20 percent
- Myeloma, risk lowered by 17 percent
- Colon cancer, risk lowered by 16 percent
- Head and neck cancer, risk lowered by 15 percent
- Rectal cancer, risk lowered by 13 percent
- Bladder cancer, risk lowered by 13 percent
- Breast cancer, risk lowered by 10 percent
One type of cancer was found to be higher in the group of exercisers, and this was malignant melanoma, by an increased risk of 27%. Researchers theorize this may be due to the fact that the exercise was occurring outside in the sunlight. Without proper skin protection, this repeated exposure would raise the risk of developing melanoma.
Other factors were not controlled for, such as the correlation between exercising and smoking or drinking alcohol, and researchers believe that may play a significant role. Further research is needed, but exercise appears to be a strong cancer combatant.
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