Most of us know that physical activity is good for us. But a new study shows that a chronic lack of physical activity can drastically increase the chance of developing cancer in the bladder and kidneys, and it suggests that engaging in more physical activity may reduce this risk.
The Centers for Disease Control and Prevention (CDC) report that, every year, almost 57,000 adults have kidney and renal pelvis cancers in the United States. Additionally, almost 14,000 people per year die from these cancers.
Bladder cancer is also widespread. According to the CDC, around 71,000 U.S. individuals developed bladder cancer in 2013, and almost 16,000 people died as a result.
A team of researchers at the Roswell Park Cancer Institute in Buffalo, NY, set out to examine the link between leading a sedentary lifestyle and the risk of developing kidney or bladder cancer.
The findings were published in the journal Cancer Epidemiology.
The researchers were led by Dr. Kirsten Moysich, distinguished professor of oncology in the Departments of Cancer Prevention and Control and Immunology at Roswell Park, and Rikki Cannioto, assistant professor of oncology also in the Department of Cancer Prevention and Control at Roswell Park.
Drs. Moysich and Cannioto, along with their colleagues, analyzed 160 people with renal (kidney) cancer, 208 bladder cancer patients, and 766 healthy controls.
Participants were asked to report on their levels of physical activity - namely, whether or not they took part in any regular or weekly recreational physical activity throughout the course of their lives. Those who said that they had never done so were classified as "physically inactive."
The researchers used unconditional multivariable logistic regression methods to calculate the odds of developing renal and bladder cancer.
Inactivity increases kidney and bladder cancer risks by up to 77 percent
Overall, the authors found "evidence of a positive association between renal and bladder cancer with lifetime recreational physical inactivity."
Specifically, they found that those who were physically inactive were 77 percent more likely to develop renal cancer and 73 percent more likely to develop cancer of the bladder.
A similar risk was found among people with obesity and people with a normal body weight - that is, having a body mass index (BMI) of below 30. This suggests that leading a sedentary lifestyle is an independent factor that influences bladder and renal cancer risk independently of obesity.
This study adds to previous data that have shown the same correlation. Former studies have also indicated a link between chronic physical inactivity and an increased risk of ovarian and cervical cancer.
However, the authors concede that additional, larger-scale, prospective studies are needed to consolidate the findings.
Dr. Moysich comments on the results and urges people to engage in a simple, moderate form of physical activity:
"We hope that findings like ours will motivate inactive people to engage in some form of physical activity. You don't have to run marathons to reduce your cancer risk, but you have to do something - even small adjustments like taking the stairs instead of the elevator, walking around the block a couple of times on your lunch hour, or parking the car far away from the store when you go to the supermarket."
Dr. Cannioto also weighs in on the results, saying that the "findings underscore how important it is to maintain a healthy lifestyle, including getting and staying active. The Department of Health and Human Services recommends 150 minutes each week of moderate physical activity or 75 minutes each week of vigorous physical activity as a way to generate significant, lasting health benefits."