People with type 2 diabetes are at higher risk for some of the most lethal cancers, including liver and pancreatic tumors, with the greatest elevation in women, studies suggesting.
An analysis of 95,000 health records shows that the risk of pancreatic cancer is almost twice as high, and women who have recently been diagnosed with type 2 diabetes are almost five times more likely to develop liver cancer.
The likelihood of developing cancer is also increased in men, with new onset type 2 diabetes being associated with a 74% increase in pancreatic cancer and almost four times the risk of liver cancer five years later.
Intestinal cancer is small, with a 34% higher risk of disease in women, and 27% higher in men with new onset type 2 diabetes compared to those without a recent diagnosis of diabetes.
“Diabetes and obesity are related to similar types of cancer,” said Owen Chip, a medical student who worked on the research with Andrew Lenehan, professor of cancer research and surgery at the University of Manchester. “Our study detected the effects of diabetes on cancer after adjusting for obesity.”
Previous studies have linked obesity to 13 types of cancer, many of which are more common in people with type 2 diabetes. However, researchers are struggling to resolve whether diabetes itself increases the risk of some or all of cancer.
In its latest research, the Manchester Group has turned its eye to the UK biobank, which holds medical and lifestyle data for 500,000 people. They looked at records of 23,750 newly diagnosed type 2 diabetes and compared them to over 70,000 matched controls without diabetes.
Cancer diagnosis tends to surge just after it is discovered that patients have diabetes, simply because they are receiving more medical tests. The researchers explained this cancer surge with better detection by ignoring cases reported within a year of diabetes diagnosis.
The study found that five years later, the risk of obesity-related cancer was 48% higher than that of recently diagnosed men with type 2 diabetes. For women, the risk for women who received a recent diabetes diagnosis was 24% higher.
However, not all obesity-related cancers have risen in diabetes. A study published in May at the European Conference on Obesity in Malaga, Spain, found that diabetics were not likely to develop endometrial or postmenopausal breast cancer.
The lifetime risk of liver and pancreatic cancer is higher in men than in women across the population. In the UK, one in 76 men and one in 130 women develop liver cancer, one in 55 men and one in 59 women develop pancreatic cancer.
Chip said it's too early to know if diabetics will benefit from cancer screening, but “in pancreatic cancer, we know that early detection is important.”
It is unclear how diabetes promotes cancer, but scientists suspect high levels of insulin, hyperglycemia and chronic inflammation. Gender differences can be caused by hormone levels, i.e. how sensitive your body is to the effects of insulin and body fat fluctuations.
Sophia Lowes of Cancer Research UK said: “This study will help to increase our understanding of the link between diabetes and cancer. While many questions remain about how and why diabetes causes cancer, such studies are essential to improve the prevention, detection and diagnosis of disease.
“Overweight and obesity cause at least 13 types of cancer. The world around us isn't always easy, but eating a healthy, balanced diet is one way to reduce your risk of cancer.
