Prolonged TV viewing may be associated with an increased risk of bowel cancer in men. This conclusion was reached by the authors of a study based on UK Biobank data, published in the British Journal of Cancer, where sedentary behaviour is considered a possible risk factor.
This is not about a proven cause of the disease, but about a statistical association. Nevertheless, the results add arguments to the discussion of how everyday habits, including physical inactivity, may affect long-term health.
What UK Biobank compared—and what signal they observed
The researchers compared groups of men with different amounts of TV viewing per day. The key comparison concerned those who spent more than 4 hours a day in front of the screen and those who watched TV for less than 1 hour a day.
In the sample, men in the group with the longest TV viewing more often developed bowel cancer during the subsequent follow-up years than those who spent minimal time watching TV. The authors emphasised the observational nature of the analysis, in which the association may reflect co-occurring habits and lifestyle, rather than a direct effect of viewing itself.
Women and men in the same dataset showed different results
A separate feature of the study was the difference by sex. According to expert commentary, in these data no association was found in women between time spent watching TV and the risk of bowel cancer.
Why the effect appeared specifically in men remains an open question. The study was not designed to examine the reasons for sex differences, so possible explanations require additional verification and new analyses, including taking behaviour and associated factors into account.
Physical activity as a factor associated with a lower risk of colon cancer
In addition to screen time, the researchers also assessed physical activity. In their results, a higher level of activity in men was associated with a lower risk of colon cancer.
In the wording, it is important to distinguish between terms. Bowel cancer is a general colloquial and medical umbrella term that includes different sections, whereas colon cancer is a specification that the authors used when describing the effect of physical activity, without automatically extending this conclusion to all forms of colorectal cancer.
Computer screen time did not mirror the TV effect
Another detail of the study looks contrasting against the overall narrative about a sedentary lifestyle. Time spent at a computer showed no association with the risk of bowel cancer.
This discrepancy raises questions about behavioural context. Watching TV often serves as a backdrop for other habits, whereas computer time may include different scenarios, from work to communication and more frequent breaks, and such differences are not always possible to measure precisely in large observational studies.
At the same time, people who play computer games are in a risk group. This scenario is as similar as possible to the “TV phenomenon” when it comes to multi-hour gaming sessions. Thus, the most dangerous games from a health perspective are those with highly engaging gameplay, as well as high-intensity player activity. The gameplay seems to allow you to take breaks, but you don’t want to.
Online casino games are also characterised by a similar impact, and they also differ in how engaging they are. To learn more about this, we decided to study information about it in more detail. The authors of the website www.xxxtremeroulette.com about an online casino with live‑roulette XXXtreme Roulette claim that roulette has some of the highest session-length figures. This suggests not only that it can rival video games in how engaging the process is, but also that uncontrolled play can be dangerous to health.
How the study was conducted and what the conclusions are based on
The analysis was based on UK Biobank, one of the UK’s largest biomedical databases. It contains information on health and lifestyle, which makes it possible to compare habits and medical outcomes in large samples.
The key study parameters were as follows:
- UK Biobank database
- more than 500,000 men and women
- a follow-up period of about 6 years
- during the follow-up period, 2,391 cases of bowel cancer were identified
- the analysis was carried out by researchers from the International Agency for Research on Cancer, Imperial College London, and the University of Oxford
- the results were published in the British Journal of Cancer
As in other studies of this type, statistical models attempt to account for some influencing factors, but it is usually impossible to completely rule out unmeasured differences between groups, especially when it comes to behavioural habits.
Why TV viewing may be a marker for other risk factors
The lead author of the study, Neil Murphy from the International Agency for Research on Cancer, noted that watching TV may be accompanied by smoking, alcohol consumption, and snacking. These factors are already known to be associated with the risk of bowel cancer, and their combination can intensify an unfavourable profile.
He also drew attention to the link between sedentary behaviour and weight gain and an increase in body fat. Excess fat can affect levels of hormones and other substances in the blood that are involved in the regulation of cell growth, and this is considered one of the possible biological pathways linking obesity and cancer risks.
Independent commentary and the practical implications of the findings
Cancer Research UK prevention expert Linda Bauld noted that the results raise interesting questions, including why computer time was not associated with risk, whereas TV was linked. As one hypothesis, she mentioned the influence of advertising for high-calorie, low-nutritional-value foods, which is more often present in TV content and may encourage overeating.
In the second part of her commentary, Bauld indicated that the increased risk was observed in men but not in women, and a possible explanation could be differences in habits while watching, such as more frequent snacking, smoking, or alcohol. Among the measures that are generally associated with a lower risk of bowel cancer, she listed maintaining a healthy weight, a higher level of physical activity, reducing alcohol intake, and a diet rich in fruits and vegetables.
How common bowel cancer is in the UK
Bowel cancer remains one of the most common cancer diagnoses among men in the UK and is the third most common among the male population. This background makes any reliable data on potential risk factors important for public health and clinical prevention.
Estimates suggest that in 2015 around 41,800 new cases of bowel cancer were registered in the UK among men and women in total. Against this backdrop, researchers are increasingly considering everyday physical inactivity as another variable that may contribute to overall risk alongside diet, weight, and harmful habits.