Increased Cancer Risk Associated with Atrial Fibrillation Diagnosis

Retrospective analysis of trial data has found that women with newly diagnosed atrial fibrillation faced an elevated risk of cancer as well.

 

Investigators gathered a median of 19.1 years of medical data on 34,691 women who participated in the Women’s Health Study between 1993 and 2013. All of the women were aged 45 years or older at baseline and none of them had been diagnosed with AF, cancer or cardiovascular disease.

 

During the course of the trial — which was undertaken to study whether aspirin and vitamin E could prevent cancer and/or cardiovascular disease — new cases of AF were diagnosed in 1,467 cohort members (4.2%) while new cases of cancer were diagnosed in 5,130 cohort members (14.8%).

 

After adjusting for potential confounding factors, the investigators found that incident AF was associated with an elevated risk of incident cancer, particularly at first. Women faced more than triple the normal risk of being diagnosed with cancer in the first 3 months after they were diagnosed with AF (hazard ratio [HR], 3.54; 95% confidence interval [CI], 2.05-6.10; P < .001).

 

The risk diminished over time but remained significant, even after the 1-year mark (adjusted HR, 1.42; 95% CI, 1.18-1.71; P < .001). The comprehensive hazard ratio, incorporating the added risk both in the first year and thereafter was 1.48 (95% CI, 1.25-1.75; P < .001).

 

Although incident AF was associated with a significantly higher risk of cancer diagnosis, it was not associated with a significantly elevated risk of cancer mortality, though the numbers did trend in that direction (adjusted HR, 1.32; 95% CI, 0.98-1.79; P = .07).

 

 

When the investigators looked to see whether the association ran in the opposite direction, they found that the answer depended on timing. Women who had been diagnosed with cancer in the past 3 months faced a significantly higher chance than cancer-free women of developing AF (HR, 4.67; 95% CI, 2.85-7.64; P < .001) but the relationship diminished thereafter (HR, 1.15; 95% CI, 0.95-1.39; P = .15).

 

“In this large, initially healthy cohort, women with new-onset AF had an elevated cancer risk beyond 1 year of AF diagnosis. Shared risk factors and/or common systemic disease processes might underlie this association,” the study authors wrote in JAMA Cardiology. “Future studies are needed to assess the mechanisms underlying this association and to determine whether a diagnosis of AF incrementally adds to existing cancer risk prediction algorithms. Regardless, optimal risk factor control in patients with AF seems prudent.”

 

The new analysis is not the first to find that AF patients face an elevated risk of cancer diagnosis. A cohort study of all 269,742 Danish patients diagnosed with AF between 1980 and 2011 found that patients who had been diagnosed with AF in the past 3 months faced 5 times the normal risk of being diagnosed with cancer. The analysis also found that, even after 24 months, the risk of cancer diagnosis remained significantly higher than normal in AF patients.

 

In an editorial that accompanied the new study’s publication, a trio of researchers from Boston University argued that the link between AF diagnosis and subsequent cancer probably is not causal.

 

“The mechanisms underlying the interrelations are probably multifactorial and include shared risk factors, increased detection due to bleeding with anticoagulation (suggested by the prominence of colon cancer), or other systemic processes,” they wrote.