AF linked to increased cancer risk in women

By Laura Cowen

Women with new-onset atrial fibrillation (AF) have a significantly increased cancer risk for at least 1 year after AF diagnosis, an analysis of Women's Health Study data shows.

"These data further emphasize the importance of risk factor reduction in patients with AF to not only reduce recurrent AF episodes but also potentially decrease other adverse outcomes", say David Conen (University Hospital, Basel, Switzerland) and co-researchers.

The cohort study followed up 34,691 women aged 45 years and older for a median 19.1 years. During this time, 1467 (4.2%) developed new-onset AF and 5130 (14.8%) were diagnosed with cancer.

Among the women with new-onset AF, 147 (10.0%) developed cancer, equating to an incidence of 1.4 cases per 100 person-years of follow-up. By comparison, the incidence of cancer in women who did not develop AF was 0.8 per 100 person-years.

After adjustment for multiple potential confounders, the researchers found that women with new-onset AF had a significant 48% higher risk of cancer than those without it.

Conen et al report in JAMA Cardiology that the risk of cancer was greatest in the first 3 months after new-onset AF, at a hazard ratio (HR) of 3.54, and although it fell after this point, the risk remained significant for at least 1 year, when the HR was 1.42.

The researchers say: "The higher short-term risk of cancer after new-onset AF could be explained by a diagnostic workup at the time of AF diagnosis." However, they add that the longer term increased risk "suggests that not all cancers were present" at this time.

To see if the relationship between AF and cancer was bilateral, Conen and team measured the incidence of AF among the 5130 women initially diagnosed with cancer during follow-up. Of these women, 142 (2.8%) subsequently developed AF, giving an incidence of 0.38 events per 100 person-years of follow-up. This compared with 0.24 AF events per 100 person-years in the women who did not develop cancer.

Although the adjusted risk for AF was a significant 20% higher for the women with cancer overall, most of the cases occurred in the first 3 months after cancer diagnosis, during which time the multivariable-adjusted HR for AF was 4.67. The risk of AF among the women with cancer versus those without was not significantly increased beyond 3 months, the researchers note.

In an accompanying editorial, Emelia Benjamin (Boston University School of Medicine, Massachusetts, USA) et al say that the findings raise the question of whether a diagnosis of AF should prompt screening for cancer, but they conclude that this is not currently warranted.

However, further research is needed because "understanding the intermediate steps that link AF and cancer in the bidirectional associations reported by Conen et al may provide valuable mechanistic and therapeutic insights with regard to both conditions", they write.

Source: JAMA Cardiol 2016; Advance online publication

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