Another meta-analysis has swung in favour of statins for patients with colorectal cancer (CRC), but Australian experts are still waiting on results from randomised controlled trials.
The meta-analysis of 14 studies by Chinese researchers linked statins to a 18-21% reduced mortality risk in patients with bowel cancer.
This latest study is one of many that suggest a benefit from taking statins as prevention for CRC, either primarily or to prevent recurrence.
But statins for CRC are still controversial as no randomised controlled trials have been done, and a 2012 meta-analysis of 27 studies showed no benefit from treatment.
“It’s an interesting concept,” Associate Professor Graham Newstead, the medical director for Bowel Cancer Australia and a colorectal surgeon at the Prince of Wales Private Hospital, said.
“From a statistical point of view, the study is pretty well done. It doesn’t mean we are going to cure people by lowering their cholesterol. It’s only suggesting that there may be some protective effect of the statins in terms of cell division and therefore getting to an end-stage with a disease.”
In the Chinese analysis, statins appeared to protect against all-cause mortality (probably by preventing heart disease). The medication was also associated with a reduction in cancer-specific mortality.
Statins could be acting on CRC directly by suppressing tumour growth, inducing apoptosis and inhibition of angiogenesis, the authors hypothesised.
“Several studies in vitro and vivo have strongly indicated the anticancer effects of statins on CRC,” the authors said.
The meta-analysis drew on studies from the UK, Denmark, the Netherlands, Germany, North
America, China and Korea. It incorporated data on patients with all different stages of CRC.
One of these studies from the UK, published in 2014, showed that colorectal cancer-specific mortality dropped by around 30% in people who took statins after a diagnosis of stage I to III CRC. This was a prospective, observational study of around 7,600 people with a follow up of up to 14 years.
But another prospective, observational study from Germany with more than 2,000 patients showed that statins were not associated with a decrease in mortality over three years.
Overall, the meta-analysis showed that statins improved survival in patients with CRC and “these effects persisted even after subgroup analysis stratified by country, tumour site, tumour stage and therapy,” the authors said.
In Australia, clinical guidelines currently don’t recommend statins for CRC patients.
The topic of statins is addressed in the Clinical practice guidelines for the prevention, early detection and management of colorectal cancer, which is produced by Cancer Council Australia.
“There has now been a number of trials with widely variable findings ranging from strong reduction in colorectal cancer risk to no association between statin usage and colorectal cancer risk,” the guidelines state.
“Despite these inconsistent findings, the accumulating clinical evidence still suggests a significant association between statin usage and reduced colorectal cancer risk.”
The meta-analysis, recently published in Cancer Medicine, would not change clinical practice in Australia, said Professor Tim Price, the chair of the colorectal cancer guidelines revision working party at Cancer Council Australia and a medical oncologist at The Queen Elizabeth Hospital in Adelaide.
“There’s quite a library of evidence that’s been published in the past, including a previous meta-analysis, which is highly suggestive of a benefit for taking statins either pre-diagnosis or post,” he said.
“But we don’t have a true randomised study, which confirms an absolute benefit to the statins. So, that’s still something that we are awaiting. We still ultimately would require for it to become standards of care.”