MI Survivors May Be at Risk for Lung, Bladder, Other Cancers

Deborah Brauser

March 15, 2015

SAN DIEGO, CA — Although not exactly sure of the underlying mechanism or whether other factors are at play, researchers from Denmark note that patients who survive an MI may be at significant risk for overall and specific types of cancer[1].

Their study, presented in a poster here at the American College of Cardiology (ACC) 2015 Scientific Sessions, examined nationwide data from Danish registries for almost 126 000 MI survivors without a history of cancer and more than three million individuals with no history of either MI or cancer. Results showed an incidence rate (IR) for any cancer of 173.5 per 10 000 person years for the MI survivors after up to 17 years of follow-up vs an IR of 85.2 per 10 000 person years for their healthy peers.

Lead author, research fellow Morten Winther Malmborg (Gentofte Hospital, University of Copenhagen, Denmark), told heartwire from Medscape that the overall results matched their hypotheses.

"We saw an especially increased risk within the first 6 months of having an MI. But even after that, there was still an increased risk of cancer, especially in the lungs and bladder," he said.

However, he noted that the significant association found between prior MI and these types of cancer could possibly be due to smoking status—but lifestyle data on smoking was not provided in the registries.

"To get into that, we'd need to look at [patient-level data], which could be included in future studies. Still, we need to have more awareness of these overall cancer risks," said Malmborg.

Future Implications?

The investigators examined records for 3 005 734 Danish individuals who were older than 29 years. Of these, 125 909 patients (62% men; mean age 62 years) received an MI diagnosis between January 1996 and December 2012. The remaining 2 879 825 were designated as the "background population."

Examining up to 17 years of follow-up data, the researchers found 363 383 cases of subsequent cancer in the background population, corresponding to the IR of 95.1 per 10 000 person-years. There were 10 680 cases in those with a history of MI (IR 167.2).

The highest relative risks for developing cancer were found during the first month following an MI (rate ratio [RR] 3.02; 95% CI 2.49–3.66). The risk then decreased steadily but stayed at a "constant rate" 6 months post-MI.

The youngest age group (between 30 and 54 years) had the highest association between MI history and increased cancer risk after the 6-month mark (RR 1.44). This rate then decreased with age (RR 1.19 for those between the ages of 55 and 66 years; RR just 1.05 for those older than 70).

Finally, increased risk for lung and bladder cancer was significantly associated with having a prior MI (RR 1.44 and 1.31, respectively).

"Focus on cancer in MI survivors is warranted," write the investigators. "This could potentially have implications on future patient care, outpatient follow-up strategies, and distribution of healthcare resources."

Malmborg noted that although the current study examined incidence, it did not look at mortality.

"We've done it indirectly through use of the causes-of-death registry, but we didn't look at it specifically. So we hope to do that next, followed by an examination of the various cardiac medications and whether they had an influence, either positively or negatively, on risk of cancer."

Malmborg has reported no relevant financial relationships. Disclosures for the coauthors are linked to the abstract.

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