Obesity, a disease characterized by an unhealthy amount of body fat, can put individuals at an elevated risk of other diseases, including diabetes, cardiovascular disease, and several types of cancer. Further, obese individuals have an increased risk of mortality compared to those at a healthy weight.
Most scientific research linking obesity to cancer comes from observational studies, which limit scientists from definitively showing that obesity causes cancer. On a basic level, this can be explained, in part, by the fact that obese individuals commonly have similarities other than high body fat. This means that, besides body weight, obese and non-obese individuals differ in various ways, including high rates of comorbidities, like diabetes, or divergent lifestyle factors, like low activity levels.
Scientific evidence suggests obesity increases the risk of at least 13 types of cancer, including endometrial, liver, kidney, pancreatic, colorectal, and breast cancers.
The general classification of obesity, based on body mass index (BMI) and calculated using height and weight, has received criticism for not accounting for muscle weight or the distribution of body fat throughout the body. Based on this narrow definition, two people with the same BMI could have different amounts of fat.
Fat distribution differs between men and women, and genetics plays a role in the observed differences between the sexes. For example, gene mutations associated with distributing fat to the legs and trunk remain more prominent in females than males.
A study published in Cancer Cell investigated if differences in body fat distribution between males and females could influence cancer risk. The researchers obtained data from the UK Biobank, an extensive research database containing genetic and health data from participants. The current study assessed data from 442,519 patients for 19 cancer sites. This prospective study analyzed the risk of developing cancer-based on obesity-related characteristics. The follow-up time for participants exceeded 13 years.
The researchers considered 14 factors referred to as “adiposity traits." These factors describe phenotypical characteristics related to obesity, including abdomen fat, waist size, and leg, body, trunk, and arm fat mass.
The study revealed that most cancer types evaluated were associated with adiposity traits. The researchers also reported that fat accumulation and distribution induce different effects between men and women in three types of cancer: colorectal, esophageal, and liver. For these cancer types, the effects of obesity appeared stronger in males than females.
This study provides a comprehensive overview of how fat accumulation and distribution influence the risk of developing several types of cancer. While the study shows that many adiposity traits infer different influences on cancer risk between men and women, the most substantial differences appear dependent on fat accumulation. Oncologists could implement this information in developing and implementing risk assessments used for cancer prevention in men and women.
Sources: J Clin Oncol, Eur J Cancer, Int J Cancer (Wang), Int J Cancer (Genkinger), PLOS One, Lancet, Nature, Nature Communications, Cancer Cell
