Heart drug (Amiodarone) may be linked to cancer risk

A drug given to some people who have heart rhythm problems could be linked to an increased risk of cancer, according to a study in Taiwan. But we need further studies to confirm these findings. By Lilian Anekwe BMJ Group News

What do we know already? Amiodarone is a drug used to treat heart problems called arrhythmias. It is usually taken as a tablet. Arrhythmias affect how the heart beats. Instead of beating in a regular rhythm, arrhythmias cause the heart to beat very quickly and in an irregular way. This can cause complications, such as blood clots and strokes.Amiodarone can help slow the heart rate down and get the heart rhythm back to normal in some people with arrhythmias. However, it's possible that for some people, this medicine might do more harm than good. This is because amiodarone remains in the body for a long time after it is taken, and this build-up can cause side effects that can affect the skin, lungs, liver, and thyroid.There is some evidence that a build-up of amiodarone may be linked with some cancers, such as thyroid cancer and skin cancer. But there haven't been good-quality studies that have looked at this, and we are a long way from being sure that the link is genuine.To find out more, researchers in Taiwan looked at 6,418 people, with an average age of 70, who took amiodarone for arrhythmias between 1997 and 2008. The researchers worked out how many doses of amiodarone people had taken in one year, and looked for a link between taking amiodarone and cancer.

What does the new study say?In total, 280 people developed some kind of cancer during the study period, which lasted an average of two and a half years. When researchers looked at the group as a whole, people who took amiodarone were no more likely than anyone else to get cancer.Although people were more likely to get cancer if they took more of the drug over time, the link between amiodarone and cancer still wasn't very strong.

How reliable is the research?The clearest answers about links between treatments and side effects come from large studies that include a lot of people. This study was fairly large, but possibly not big enough to say for sure whether there is a link between amiodarone and cancer.The researchers warned that two and a half years might not be long enough to look for a cancer link, as some cancers take longer than this to develop.

What does this mean for me?If you are taking amiodarone to treat heart arrhythmia, there is nothing in this study that suggests you should stop taking it. There would need to be larger and longer studies showing a stronger link before doctors advised people to stop taking the drug. In the meantime, if you have concerns about amiodarone, you can discuss them with your doctor.