Researchers found that men who watched TV for more than 4 hours per day were likelier to develop colorectal cancer over 6 years when compared with those who spent less time in front of the TV.
But it's not all doom and gloom; the study also found that men could lower their risk of colon cancer by increasing their physical activity levels.
Lead researcher Dr. Neil Murphy, of the International Agency for Research on Cancer in France, and colleagues recently reported their results in the British Journal of Cancer.
A wealth of research has pinpointed sedentary behavior as a major cause of health problems, and watching TV is one such behavior.
A recent study reported by Medical News Today, for example, revealed that watching too much TV could increase the risk of potentially fatal blood clots, while other research found that it may harm sleep quality.
Now, researchers claim that binge-watching TV could raise the risk of colorectal cancer — for men, at least.
Colorectal cancer and sedentary behavior
Colorectal cancer, or bowel cancer, is cancer that begins in the colon or rectum. According to the American Cancer Society (ACS), there will be 97,220 new cases of colon cancer and 43,030 new cases of rectal cancer diagnosed in the United States this year.
Lack of physical activity is a known risk factor for colorectal cancer, so it will come as no surprise that watching TV for hours at a time might contribute to the disease.
"Previous research suggests that watching TV may be associated with other behaviors, such as smoking, drinking, and snacking more, and we know that these things can increase the risk of bowel cancer," says Dr. Murphy.
"Being sedentary is also associated with weight gain and greater body fat," he adds. "Excess body fat may influence the blood levels of hormones and other chemicals which affect the way our cells grow, and can increase bowel cancer risk."
Colorectal cancer risk increased in men
Dr. Murphy and colleagues came to their findings by analyzing data from UK Biobank, which is a health database of around 500,000 men and women who are based in the United Kingdom.
The team gathered information on how many hours each subject spent engaging in sedentary activities, such as watching TV and using a computer, per day.
The researchers also monitored how many of them developed colorectal cancer over 6 years of follow-up. A total of 2,391 colorectal cancer cases were identified.
Compared with men who watched TV for up to 1 hour each day, those who watched TV for at least 4 hours per day were found to have a 35 percent greater risk of colorectal cancer.
The team found no link between time spent watching TV and the risk of colorectal cancer in women.
Exercise reduced colon cancer risk
Interestingly, computer use was not associated with increased colorectal cancer risk in men. Prof. Linda Bauld, who is a cancer prevention expert at Cancer Research UK, suggests that this may be down to the content that men are exposed to with TV viewing.
"There is evidence," she explains, "that greater exposure to TV junk food adverts increases the likelihood of eating more, which will also increase your chances of becoming overweight."
On a more positive note, the researchers also found that men who engaged in higher levels of physical activity had a 23 percent lower risk of developing colon cancer, compared with men who had low physical activity levels.
Quite simply, this suggests that some men should seriously consider swapping time in front of the TV for time at the gym.
However, Prof. Bauld notes that the research raises some important questions, such as: why does watching TV for prolonged periods seem to raise colorectal cancer risk in men but not women?
"The study didn't look at this directly, but it could be because men might smoke, drink, and eat more unhealthily than women while watching TV," Prof. Bauld speculates.
"What we do know," she goes on, "is that keeping a healthy weight, cutting back on alcohol, being physically active, and eating a diet rich in fruit and vegetables are known to cut your risk of bowel cancer."