Heart Medication May Increase Cancer Risk

Cancer risks linked to amiodarone therapy for arrhythmia

(RxWiki News) Problems with medications can be discovered years after they’ve been on the market. One very popular heart medicine that’s been around since 1985 may fall into this category.

After reviewing data on thousands of people, scientists have found a possible increased cancer risk among people who have taken higher doses of amiodarone, sold under the brand name Nexterone.

The higher cancer risks were seen mostly in men and those who took high doses of the drug during the first year of amiodarone therapy.

These findings suggest a need for further research into a possible association between amiodarone and cancer.

"Talk to your pharmacist about medication side effects."

Amiodarone is used to treat an irregular heartbeat (arrhythmia). It takes a long time for amiodarone to break down in the body, so it can build up in the soft tissues over time.

Earlier studies have suggested that amiodarone may increase the risk of certain cancers. No large studies have investigated this possibility.

To examine the association, Vincent Yi-Fong Su, MD, of the Taipei Veterans General Hospital in Taiwan, and his colleagues examined data from 6,418 individuals taking amiodarone. Participants were followed for just over two and a half years.

The median age of participants was 70. Researchers noted other conditions or illnesses the participants had.

During the follow-up, 280 (about 4.5 percent) study members developed various types of cancer.

Here’s what researchers uncovered:

  • The incidence of cancer was increased within one year of beginning amiodarone, but not after one year. 
  • People who took higher doses – more than 180 cumulative defined daily doses – of amiodarone during the first year were at higher risk of developing cancer than the general population.
  • People who took less than 180 cumulative defined daily doses did not have increased cancer risks.
  • Men who took the medication also had higher risks.
  • The combination of being male and taking higher doses resulted in the highest increased cancer risk.
  • Compared to women and those who took lower doses, men who took the higher doses of amiodarone within the first year were 46 percent more likely to develop cancer.
  • After adjusting for age, sex and other illnesses, people who took high doses of amiodarone had nearly twice the risk of developing cancer as those taking lower doses.

Dr. Su said in a press release that more research into this possible association is needed. He added, “Also, when prescribing amiodarone, doctors need to keep in mind that this medication may increase cancer risk.”

This research was published April 8 in Cancer, the peer-reviewed journal of the American Cancer Society. The study was supported in part by a grant from Taipei Veterans General Hospital. The authors made no disclosures of conflicts of interest.

Review Date: 
April 7, 2013