Updated: December 22, 2017
You may have heard of someone getting cancer who you never would have expected- they exercised, didn’t smoke, and avoided all of the normal carcinogens. Researchers have figured out one more piece of the cancer puzzle: prolonged periods of sitting increase your risk of cancer.
Ergotron, a global manufacturer of digital display mounting, furniture, and mobility products including sit-stand desks, commissioned a study in 2013 that found that 86% sit all day, every day. In addition to the extensive that sitting that people do at work, 36% sit another 1-2 hours while watching TV. 10% game another 1-2 hours, 25% sit for other activities such as reading, and 29% use their home computers for another 1-2 hours.
In total, Americans are sitting an average of 13 hours a day and sleeping an average of 8 hours resulting in a sedentary lifestyle of around 21 hours a day. While Americans know about the importance of exercise, only 31 percent go to the gym, and 56 percent devote less than $10 per month to staying active.
Women who sit for at least six hours every day have a higher risk of suffering from cancer than those who sit for less than three hours daily. According to a study referenced to on the American Cancer Society website, the longer time a woman spends sitting can significantly raise her risk of cancer, specifically ovarian, breast, and multiple myeloma. And according to the British Journal of Cancer, the chances of endometrial cancer are higher as well (cancer of the uterus).
For both men and women, according to the British Journal of Cancer, sedentary behaviour is associated with an increased risk of colon cancer.
Some of the first research done on the hazards of extended periods of sitting started in the 1960s when research was done on the rates of mortality from postal workers Research on the negative consequences of sitting dates back to the 1960s, Colditz said, when researchers examined how postal workers (who walked all day) vs. office workers.
For men, the British Journal of Cancer concludes, “Our results suggest that not sitting for most of the time during work or occupational activity and walking or bicycling more than 30 min per day during adult life is associated with reduced incidence of prostate cancer.”
For many years experts have been aware that exercise reduces the chances of many different types of cancers, but now they recommend a two-part strategy: regular exercise and avoid prolonged periods of inactivity. “It seems highly likely that the longer you sit, the higher your risk,” says Neville Owen, PhD, of Australia’s Baker IDI Heart and Diabetes Institute.
Dr. Christine Friedenreich, research scientist and epidemiologist at Alberta Health Services in Canada, estimates that higher activity could prevent nearly 100,000 cases of breast and colon cancer in the U.S. each year.
The American Cancer Society recommends a 1 or 2 minute break every hour, and many experts recommend a break every 20 minutes.
Researchers say that extended periods of sitting is an independent factor, meaning that if you sit for long periods of time, it doesn’t matter if you’re not obese, you don’t smoke, and that you exercise. Extended periods of sitting increases your chance of cancer.
Dr. Graham Colditz, of the Siteman Cancer Center and Department of Surgery at the Washington University School of Medicine in St. Louis, explains “Obesity is a major driver for multiple cancers, and research has shown that obesity and sedentary behavior are related. Studies have also shown that more time spent sitting after meals is related to higher blood-sugar levels, which have also been associated with an increased risk of colon cancer,” he said.
In a study published in the Journal of the National Cancer Institute, sedentary behavior was associated with a 24% greater risk of developing colon cancer, a 32% higher risk of endometrial cancer, and a 21% increased risk of lung cancer. They also found that watching TV was linked to a 54% higher risk of colon cancer and a 66% greater risk of endometrial cancer. And for every additional two hours that participants spent sitting during the day, their risk of colon cancer rose by 8%, and their risk of endometrial cancer went up by 10%.
4.8 in 100 Americans get colon cancer during their lifetime, and 2.7 per 100 women get endometrial cancer, said Dr. Graham Colditz, of the Siteman Cancer Center and Department of Surgery at the Washington University School of Medicine in St. Louis, who wrote an editorial accompanying the study.
Another study published in the British Journal of Sports Medicine found that for every hour of television you watch after age 25, your life expectancy goes down by 22 minutes.
Increased Mortality Rates and Sitting
Additionally, some studies that link sitting time and cancer have also found a higher chance dying at a younger age for both men and women. According to Alpa Patel, one of the authors of the study and the strategic director of the American Cancer Society, there’s a strong link between prolonged sitting and dying at a young age even for those who regularly perform physical activities. Researchers found that women who have more than 6 hours of sitting time have a 37% risk of death in comparison to those who sit for less than three hours. Men, however, have a 17% increased risk of facing death if they sit for at least 6 hours every day. It’s even worse if you don’t exercise at all: the mortality rate is 48% higher for men and 94% higher for women.
A study from 2012 reported that the average life expectancy in the United States would increase by 2 years if excessive sitting time were reduced by 3 hours a day.
This involves sitting, working at a PC or watching television. He further said that even if you’re a regular exerciser, it doesn’t negate the damage done by long periods of inactivity. One researcher said it was like smoking during the day, and exercising at night. The exercise doesn’t get rid of the damage done by smoking during the day. For this reason the American Cancer Society highly recommends getting up and moving throughout your day.