The link between obesity and cancer has increasingly been emphasized in public health messages, but is the current message correct?
"Being overweight or having obesity increases your risk of getting cancer," warns the US Centers for Disease Control and Prevention. It warns that overweight/obesity is "linked with a higher risk of getting 13 types of cancer...[which] make up 40% of all cancers diagnosed in the United States each year."
But that message, which is also promulgated by many cancer organizations, is based on data from observational studies, which have many limitations.
A new study based on Mendelian randomization studies has come to a slightly different conclusion and has found a potential causal association with just six cancers.
In addition, it found an inverse relationship for breast cancer, in which early-life obesity was associated with a reduced risk of breast cancer, and the relationship with obesity was "complicated" for lung and prostate cancer.
The study, headed by Zhe Fang, MBBS, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, was published in the Journal of the National Cancer Institute on March 1.
"For a seemingly straightforward question of whether excessive body fatness causes cancer, the answer may not be straightforward after all," writes Song Yao, PhD, professor of oncology, Roswell Park Comprehensive Cancer Center, Buffalo, New York, in an
