Amiodarone may increase the risk of cancer, especially in men and those with prolonged exposure, say researchers.
The Taiwanese researchers identified 6,418 patients who were treated with amiodarone for more than 28 days from 1997 to 2008. The median follow up was 2.57 years and median age at diagnosis was 70 years. The researchers determined the risk of cancer in the amiodarone-treated cohort, compared with the risk of cancer in the general population. The analysis was adjusted for age, sex, and comorbidities but not for risk factors such as smoking, environmental exposure, family history of malignancy, alcohol use, and obesity which were not available.
Some 280 cancers were identified, of which 124 were gastrointestinal cancers, 47 genitourinary cancers, 22 head and neck cancers, 11 hematologic cancer, and one case of thyroid cancer. The incidence of cancer was 32% higher within the first year of therapy with amiodarone, compared with the incidence of cancer in the general population, but not after one year. Men had the highest risk, especially those aged 20 to 59 years, compared with women. The incidence of cancer increased after three years with a 28% increase in incidence in those who had prolonged exposure to amiodarone. Patients with drug exposure under 180 cDDDs were not found to be at high risk.
What does this study mean for GPs?
Amiodarone is commonly prescribed for the management of arrhythmia including atrial fibrillation. They concluded: ‘Although extensive screenings for occult cancers in patients currently undergoing treatment with amiodarone appears to be impractical, we suggest that cancer events should be routinely reported in future amiodarone trials, and further observational research is necessary.’