[Sportschosun reporter Jang Jong-ho] A new study has found that a sedentary lifestyle can raise not only the risk of developing cancer, but also the risk of dying from it. On the other hand, just 30 minutes of light walking a day was shown to significantly reduce the risk of cancer death.
Researchers from the United States, the United Kingdom and Australia said that, after analyzing the health data of 91,292 adults, they found that the longer people spent sitting continuously, the higher their risk of developing and dying from several types of cancer became. The findings were published in the international journal PLOS Medicine.
The researchers asked adults aged 37 to 73 enrolled in the UK Biobank to wear a wrist activity monitor for 24 hours a day and recorded their physical activity for about a week. They then followed the participants for an average of 12 years to analyze cancer incidence and mortality.
The analysis showed that each additional hour of prolonged sedentary behavior, defined as spending more than 90% of a 30-minute period sitting continuously, was associated with a 3% increase in overall cancer risk and a 9% increase in the risk of death from cancer.
In particular, the risk of obesity-related cancers such as colorectal cancer (CRC), pancreatic cancer and renal cell carcinoma rose by 5%. The risk of cancers linked to diabetes mellitus, including breast cancer, liver cancer and thyroid cancer, also increased by 5%.
The researchers explained that sitting for long periods may increase chronic inflammation in the body and promote cellular DNA damage, creating an environment in which cancer cells can more easily develop. They added that a lack of physical activity may also raise insulin resistance, potentially encouraging tumor growth and cancer cell survival.
By contrast, even breaking up sitting time from time to time brought measurable health benefits.
People who frequently interrupted sedentary behavior by standing up, walking briefly or moving around had a 6% lower risk of developing cancer. Their risks of obesity-related cancer and diabetes-related cancer fell by 9% and 10%, respectively. The risk of dying from cancer was also 18% lower.
The researchers said that replacing just 30 minutes of sitting time a day with light physical activity such as walking reduced the risk of cancer death by 18%.
Replacing 30 minutes a day with moderate-intensity exercise such as brisk walking or cycling cut the risk of cancer death by 8%. Adding just five minutes a day of vigorous exercise, such as running, swimming or uphill hiking, reduced the overall risk of cancer by 4%.
However, the researchers noted that the findings do not prove a causal link showing that prolonged sitting directly causes cancer. Still, they said the results provide important evidence that reducing sedentary time and making a habit of moving regularly may help prevent cancer and improve overall health.
The researchers emphasized, "The health effects of a sedentary lifestyle may depend not only on how long you sit, but also on whether you break it up with activity in between." They added, "Current health guidelines focus on moderate-to-vigorous exercise, but light movement should never be overlooked."
Jang Jong-ho, Sportschosun reporter bellho@sportschosun.com
