We have made our lives comfortable but our bodies have paid the price

How do a sedentary lifestyle and excess body weight influence cancer risk, and what's the solution?

KATHMANDU: Our bodies are designed for physical activity. But today, it is optional. Along with modernisation, exercise is gradually being removed from our lives. We sit when we travel, work, eat or relax. While this may seem obvious, chronic physical inactivity coupled with overweight or obesity has been linked to biological circumstances that foster cancer risk.

The biology behind the risk

Excess fat is not just an energy source stored in our body. Adipose tissue is biologically active and influences hormone levels, metabolism, inflammation and immune function.

Adipose tissue, for instance, becomes an essential source for estrogen in a female after menopause. Also, higher estrogen exposure may encourage growth of hormone-sensitive tissues in our body and lead to a greater risk of postmenopausal breast and endometrial cancer linked to obesity.

Insulin resistance, elevated levels of insulin and insulin-like growth factors have also been associated with obesity. Recent research has pointed out obesity’s association with chronic, low-grade inflammation and changes in inflammatory and metabolic signaling, which may create an environment more favourable for cancer development. It can influence cell growth and survival.

Hence, cancer risk combines hormonal, metabolic, inflammatory and tissue-specific mechanisms, but with different intensities to each organ.

Which cancers are linked to excess body weight?

The evidence is strong for a particular association between excess body weight and at least 13 cancer types, including the cancer of the endometrium, colon, rectum, kidney, liver, pancreas, gallbladder, ovaries, thyroid, meninges, and others.

But this does not prove that excess weight guarantees cancer. It means that, across populations, increasing fat increases the risk of cancer in the body.

Sedentary lifestyle: A modifiable risk factor