Obesity, HDL cholesterol & cancer

Being obese is known to be associated with increased health problems. These include diabetes, heart diseases, sleep apnoea and joint problems to name a few. It is also known that obese women have an increased risk of breast cancer. Is this association true for other cancers too?

Researchers from several universities from both sides of the Atlantic analysed the pooled data from the National Cancer Institute Pancreatic Cancer Cohort Consortium (PanScan) to look at possible association between obesity and risk of pancreatic cancer. The study included 2170 cases of pancreatic cancer and 2209 controls (Arch Intern Med 2010; 170: 791 – 802). They recorded body mass index (BMI) [< 18.5 underweight, 18.5 – 24.9 normal weight, 25.0 – 29.9 overweight, 30.0 – 34.9 obese and 35.0 severely obese], waist circumference and waist to hip ratio. In men, the risk of pancreatic cancer in those with the highest quartile of BMI is increased by 33% as compared to those with the lowest quartile BMI. In women the increased risk is 34%. An increased waist to hip ratio, between the highest and lowest quartile, was also associated with an 87% increased risk of pancreatic cancer in women.

We have two types of cholesterol in our body: ‘good’ cholesterol, namely high-density lipoprotein cholesterol (HDL-C), and ‘bad’ cholesterol called low-density lipoprotein cholesterol (LDL-C). We know that people with adequate levels of HDL-C are protected from heart disease. Does having more good cholesterol also protect you from cancer?

Researchers from Tufts University in Boston, USA, examined the relationship between HDL-C levels and the risk of developing cancer in 24 large randomised controlled trials (RCTs) of lipid-altering interventions (J Am Coll Cardiol 2010; 55: 2846 – 2854). The study found that there was a significant inverse association between baseline HDL-C levels and the rate of incident cancer. In other words, the higher the HDL-C level, the lower is the risk of cancer. After controlling for variables such as LDL-C level, age, BMI, sex and smoking status, the study found that for every 10 mg/dL increase in HDL-cholesterol, there is a 36% lower risk of developing cancer.

Most individuals put on weight because they eat more than they need. Whether you manage to lose weight or not depends on your motivation and determination. Participants in the reality show ‘The Biggest Loser’ manage to lose significant amounts of weight because they are being motivated to do so. Not everyone will get the chance to go on the show in order to be motivated. However, is the knowledge that becoming obese will increase your risk of developing cancer not enough to motivate you to keep trim?