1.44 million people, ages 19 to 98, in the U.S. and Europe, were followed for a median of 11 years during which 187,000 new cases of cancer occurred. Leisure-time physical activity was associated with a lower risk of cancers of the colon, breast, endometrium, esophagus, adenocarcinoma, liver, stomach, kidney, head, neck, rectum, bladder and lung, and myeloid leukemia and myeloma (JAMA Internal Medicine, May 16, 2016).
Lack of Exercise Increases Risk for Cervical Cancer
Cervical cancer is well known to be caused by a common venereal disease called Human Papilloma Virus (HPV). Half of all North American women will be infected with the HPV that causes cervical cancer, but almost all of these women will clear the virus and never get the cancer. Many studies have been done to explore why, in one of about 250 women, the HPV will proceed to cervical cancer and how you can reduce your risk.
A new study shows that women who do not engage in any regular moderate or vigorous physical activity are twice as likely to develop cervical cancer as women who exercise at least four times a month (Journal of Lower Genital Tract Disease, May 13, 2016). The control group consisted of women who came to a women's gynecologic clinic because of suspected cervical cancer and did not have that cancer. Other studies have shown the same results. Being overweight and not exercising increased cervical cancer risk in Korean women (PLoS One 2013; 8(6): e66555). Not exercising, increased sitting time and being overweight were associated with increased risk for abnormal Pap smears and cervical cancer in Australian women (Health Promot J Austr 2013; 24(3): 219-23).
How can lack of exercise and excess weight increase risk for a disease caused by a virus? We do not know, but I can speculate. Extensive data show that inflammation (an overactive immunity) is associated with increased risk for many cancers including cervical cancer. Inflammation damages your immunity to allow HPV to turn normal cells into cancers. See Reduce Inflammation to Help Prevent Cancer. Not exercising and being overweight are two major causes of inflammation. Full fat cells can cause a high rise in blood sugar that increases insulin, insulin-like-growth factor, and other hormones that are associated with increased cancer risk. Resting muscles do nothing to lower high blood sugar. On the other hand, contracting muscles pull very large amounts of sugar from the bloodstream and don't even need insulin to do so.
HPV Also Causes Many Other Cancers
Almost all cases of cervical cancer are caused by some of the more than 150 Human Papilloma Viruses. So are most cases of cancers of the anus, middle part of the throat, soft palate, base of the tongue, tonsils, mouth, vagina, vulvar lips of vagina and penis, and some types of skin cancers.
Almost all North Americans acquire some of these viruses during their lifetime, most commonly from sexual exposure. There is no medical treatment, but most people clear the virus themselves with no medical treatment whatever in six to nine months. Those who do not clear the virus are at high risk for developing cancers.
Anything that weakens or misdirects your immunity increases your chances of having these HPV viruses cause cancer: lack of exercise, being overweight, having high blood sugar or diabetes, being exposed to radiation, smoking, excess alcohol, chronic inflammation from any source, and so forth.
Your diet can help to keep your immune system functioning properly to prevent inflammation; see my report on anti-inflammatory and pro-inflammatory foods.