Obesity has been proven to be a major risk factor for several cancers. Weight gain during adulthood has been tied to increased cancer risk, but there is a little body of knowledge that has identified accurate timing and duration of weight gain.
Across the globe, more than 1.9 billion adults are overweight, and of these, more than 650 million are obese. Overall, about 13 percent of the world’s adult population was obese in the same year. A person is considered obese if the BMI (body mass index) is 30 or more, and a BMI of more than 25 is considered overweight.
A new study by researchers at the University of Bergen in Norway found that people who have a BMI of more than 25 and those with more than 30 are at a higher risk of developing various cancers. The researchers examined the impact of BMI and weight changes over time, on obesity- and non-obesity-related cancers.
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Obesity and cancer risk
The findings of the study, which was published in the International Journal of Epidemiology, shows that if a person is overweight before the age of 40, he or she is at a higher risk of developing cancer by 15 percent for all obesity-related cancers, 29 percent for male colon cancer, 58 percent for male renal-cell cancer, and 70 percent for endometrial cancer.
“Obesity is an established risk factor for several cancers. In this study, we have focused on the degree, timing, and duration of overweight and obesity in relation to cancer risk," Tone Bjørge, professor at Department of Global Public Health and Primary Care, University of Bergen, said.
To land to their findings, the team pooled health data from six cohorts in Europe and included 221,274 participants with two or more height and weight measurements, between 1972 and 2014. The cancer cases were determined through linkage with national cancer registries.
At follow-up, there were 27,881 cancer cases diagnosed, where more than 9,000 were obesity-related. Those who were overweight before they turned 40 had an increased risk of obesity-related cancers in both men and women, compared to those who had a normal weight. The risk is highest for endometrial cancer, accounting for 70 percent.
“Adult weight gain was associated with increased risk of several major cancers. The degree, timing, and duration of overweight and obesity also seemed to be important. Preventing weight gain may reduce the cancer risk,” the researchers concluded in the study.
Obesity heightens risk in the long run
The researchers included people with two or more measurements acquired at least three years apart and before being diagnosed with cancer. The participants were followed for over 18 years, on average. They found that obese participants, those with a BMI of 30 or more, at the first and second health assessment had the highest risk of developing obesity-related cancer than those with a normal BMI. The risk increased by about 64 percent for males and 48 percent in females.
To reduce the risk of getting cancer in the future, it is recommended to maintain a healthy diet. Obesity is now a global health problem, and it is related to a multitude of complications, including an increased risk of cancer. The study results show that being overweight and obese may increase the risk of cancers like colon, postmenopausal breast, renal-cell, and endometrial cancers.
Preventing weight gain is crucial in helping people ward off the chances of getting cancer.
"Our key message is that preventing weight gain may be an important public health strategy to reduce the cancer risk," Tone Bjørge, study co-author, said.
Bjørge, T., Häggström, C., Ghaderi, S., Nagel, G., Manjer, J., Tretli, S., Ulmer, Hanno, Harlid, Sophia, Rosendahl, A., Lang, A., Stattin, P., Stocks, T., and Engelnand, A. (2019). BMI and weight changes and risk of obesity-related cancers: a pooled European cohort study. The International Journal of Epidemiology. https://academic.oup.com/ije/advance-article-abstract/doi/10.1093/ije/dyz188/5576152?redirectedFrom=fulltext