High levels of HDL cholesterol 'may cut colon cancer risk'

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The European Prospective Investigation into Cancer and Nutrition (EPIC) study is tracking the long-term impact of diet on cancer development in more than half a million people in Europe.

Researchers have analysed a subset of these participants in order to investigate the possible links between blood fats and bowel cancer risk.

The research team looked at 1,200 people who developed bowel (colorectal) cancer, along with a further 1,200 people who were cancer-free.

Participants provided blood samples at the start of the study and completed questionnaires about their diet.

The researchers found that people with the highest levels of HDL and another blood fat, called apoliprotein A (apoA), were the least likely to develop colon cancer only.

For every 16.6mg/dl increase in HDL, the risk of colon cancer dropped by 22 per cent, while for every 32mg/dl increase in apoA, the risk of the disease fell by 18 per cent.

However, HDL and apoA levels did not appear to be associated with a reduced risk of rectal cancer.

The researchers also found that, when people who had only been monitored for two years - and therefore may have already been undergoing cancerous changes at the start of the study - were excluded from their analysis, only HDL levels were associated with a reduced risk of colon cancer.

Writing in the journal Gut, the study authors observed that low HDL levels have previously been linked to higher levels of pro-inflammatory proteins.

They concluded: "It still remains to be established whether low HDL concentrations are just correlated with other truly detrimental pathways, whether they are intermediate factors in the colon carcinogenic process, or are a true risk factor initiating a mechanistic path on the road to colon cancer."

Yinka Ebo, senior health information officer at Cancer Research UK, said: "We know that bowel cancer is more common in people who carry excess weight. Altered blood cholesterol levels often go hand-in-hand with obesity and this study aimed to find out if this may be behind the cancer link.

"The researchers found that high levels of HDL 'good' cholesterol could protect against colon cancer, but not bowel cancer overall, and they couldn't explain why this might be. The next step will be to carry out a larger, longer-running trial to see if these findings are seen again and to discover how HDL cholesterol might lower the risk of the disease.

"Keeping a healthy body weight is one of the best ways to cut your risk of many cancers including bowel cancer."

Reference

1. van Duijnhoven FNB, Bueno-De-Mesquita HB, et al. Blood lipid and lipoprotein concentrations and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition. Gut 2011. doi: 10.1136/gut.2010.225011

klíčová slova: high-density lipoprotein (HDL), good cholesterol, bowel cancer