Watching too much TV can give you colorectal cancer

When you’re mindlessly flipping through channels and spending hours in front of the TV, you could be doing a lot more than entertaining yourself – you might also be raising your chance of getting colorectal cancer.

Last year, there were 1.8 million new cases of colorectal cancer globally, and it took the lives of 881,000 people. Although it used to be a disease that tended to strike people older than 50, there have been increasing numbers of new cases affecting people in their 20s and 30s in recent years.

The scientists looked at nearly 90,000 women who were part of the Nurses’ Health Study II. All of the women involved were between the ages of 25 and 42 when the study started in 1991. By the end of the two decades of the study, 118 women had been diagnosed with young-onset colorectal cancer.

The researchers found that those who spent more than an hour sitting in front of the TV per day had a 12 percent higher risk compared to those who watched less TV, while those who spent two hours or more per day watching TV had a 70 percent higher risk of the deadly illness.

The findings mark the first time researchers have identified sedentary behavior as a factor explaining the spike in colorectal cancer among people younger than 50, although it was already known to play a role in colorectal cancer after age 50. Young-onset colorectal cancer is often more aggressive than the type that strikes later in life and has some distinctive biological features. In addition, it’s often more advanced by the time it is diagnosed, which means survival rates are poorer.

The findings were consistent in women without a family history of colorectal cancer, and the link was stronger for rectal cancer versus colon cancer.

This shows just how important it is to stay active. If you think you can get away with watching more TV because you’re thin, think again: The associations were independent of people’s weight and exercise levels. The researchers report that other forms of sitting at home, like time spent at a desk or meal time, did not affect the risk of colorectal cancer.

The link was found after adjusting for known risk factors like diet, exercise, body mass index, family history and smoking. Their findings were published in the journal JNCI Cancer Spectrum.

Diet is also important

While being sedentary for long periods – regardless of how much you exercise – could be putting you at risk, it’s also important to avoid eating processed foods, especially processed meat. Processed meat has been classified as a Group 1 carcinogen by the World Health Organization’s International Agency for Research on Cancer, placing it in the same category as asbestos exposure and smoking tobacco. Epidemiological studies have shown that eating processed meat can cause colorectal cancer, and it has also been linked to stomach cancer. Processed meats include foods like hot dogs, sausages, beef jerky, canned meat, and cold cuts.