Chronic disturbances to levels of insulin and glucose in the body may be the culprits behind obesity-linked cancers, according to a new study.
That's because of insulin's role in regulating blood glucose, which in turn fuels cell growth, according to the study's researcher Niyati Parekh, an assistant professor of public health nutrition at New York University.
"Obese individuals are more likely to have higher concentrations of both insulin and glucose, an undesirable condition that may promote cancer cells to grow, multiply, and spread rapidly, as compared to individuals who do not have these abnormalities," Parekh said in a statement.
The study, published in the journal Cancer Epidemiology, Biomarkers, and Prevention, is based on data from the 60-year Framingham Heart Study. Data from 4,615 people were analyzed for the study; the participants were recruited between 1971 and 1975, and researchers followed them until 2008. Data on diet, exercise and medical history were collected from the three generations of people followed in the study.
By the end of the study, researchers identified 787 cancers related to obesity: 217 breast cancer cases, 136 colorectal cancer cases and 219 prostate cancer cases.
Researchers found that impaired fasting glucose raised the risk of obesity-related cancer by 27 percent, after taking into account other factors such as age, alcohol use, smoking, sex and body mass index. The link between impaired fasting glucose and obesity-related cancer was especially strong among smokers.
"Earlier IFG [impaired fasting glucose] exposure (>10 years before) increased obesity-related cancer risk, particularly for colorectal cancer," researchers wrote in the study.
There were also associations between higher insulin and hemoglobin A1C levels (indicative of average blood sugar levels) and increased risk of obesity-related cancer.