Longtime AFib patients see lower cancer risk

Atrial fibrillation (AFib) patients face higher odds for short-term cancer diagnoses but, depending on how long they've had AFib, the could face lower odds for cancer in the long run, a January study states.

Though cancer has been weakly linked to AFib in the past, atrial fibrillation is more commonly associated with older age, male sex, diabetes, hypertension, smoking and alcohol abuse, congestive heart failure and vascular diseases, Walid Saliba, MD, and colleagues wrote in PLOS ONE. In turn, AFib itself has been associated with an increased risk of congestive heart failure, stroke and thromboembolism.

“Cross-sectional studies showed that patients with cancer were more likely to have prevalent AFib than those without cancer,” Saliba et al. wrote. “Although the temporal nature of the association cannot be determined from cross-sectional studies, it has been suggested that cancer could promote the development of AFib.”

Saliba’s team drew data from two large-scale prospective cohort studies—the Molecular Epidemiology of Colorectal Cancer trial and the Breast Cancer in Northern Israel Study—to better understand the nature of the cancer-AFib relationship. Combined, the study population totaled nearly 20,000 patients.

The researchers used a case-control study approach to evaluate AFib as a risk factor for cancer, while a cohort study approach was employed to study incident cancer as a risk factor for AF.

According to the paper, AFib was associated with significantly reduced odds of cancer in the case-control approach, while cancer wasn’t significantly associated with an elevated AFib risk in the cohort approach. The immediate period after an AFib event—90 days or less, the authors wrote—was linked to a 1.85 times increased risk of cancer, while the immediate period after a cancer diagnosis led to a 3.4-fold increased risk of AFib.

Still, it’s not all bad news—while AFib is associated with a shorter-term risk of cancer, the authors found that long-term risk of the disease in these patients actually decreased.

“These findings probably reflect both the effect of acute transient conditions associated with new cancer diagnosis and detection bias,” Saliba and colleagues wrote. “Similar results were identified with colorectal and breast cancer cases.”