"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," said study author Tone Bjorge, Professor at University of Bergen in Norway.
For the findings, published in the International Journal of Epidemiology, the research team wanted to find out how adult overweight (BMI over 25) and obesity (BMI over 30) increase the risk of different types of cancer.
The researchers used data for 2,20,000 individuals from the Me-Can study, with participants from Norway, Sweden and Austria.
Data from health examinations, including information on height and weight, were linked to data from national cancer registries.
According to the researchers, 27,881 individuals were diagnosed with cancer during follow-up, of which 9,761 (35 per cent) were obesity-related.
The study showed that if you were overweight before age 40, the risk of developing cancer increases by: 70 per cent for endometrial cancer, 58 per cent for male renal-cell cancer, 29 per cent for male colon cancer and 15 per cent for all obesity-related cancers (both sexes).
Obese participants (BMI over 30) at the first and second health examination had the highest risk of developing obesity-related cancer, compared to participants with normal BMI.
"The risk increased by 64 per cent for male participants and 48 per cent for females," Bjorge added.