SAN DIEGO– The risk of developing cancer is significantly higher in survivors of an acute MI compared to the general population, according to a large Danish national registry study.
“Greater focus on long-term cancer risk is warranted in MI survivors. This could potentially have implications on future patient care for MI patients, outpatient follow-up strategies, and distribution of health care resources,” Morten Winther Malmborg said at the annual meeting of the American College of Cardiology.
Morten W. Malmborg
He presented a nationwide cohort study including 3,005,734 Danish adults with no baseline history of MI or cancer who were followed for up to 17 years in the comprehensive Danish National Patient Registry. During the study period, 125,926 of these individuals had a nonfatal MI.
The subsequent incidence of cancer in the MI survivors was 167 cases per 10,000 person-years compared with 95 per 10,000 person-years in the control group, reported Mr. Malmborg, a fourth-year medical student at the University of Copenhagen.
Cancer diagnoses of all types were highest by far in the first 6 months post-MI, which he attributed to surveillance bias, since that was a period of increased medical contact. However, after he and his coinvestigators excluded the cancers diagnosed during that initial 6-month period, the post-MI group still had a highly significant 11% increased relative risk for cancer overall during the period from 6 months through 17 years post-MI.
The younger a patient was when the MI occurred, the greater the subsequent cancer risk. Individuals who had a nonfatal MI at age 30-54 had a 44% greater risk of cancer overall at 6 months–17 years post-MI compared, with the control group. Those who had an MI at age 55-69 had a 19% increased cancer risk compared to controls, while those whose MI occurred at age 70-99 had a modest but still statistically significant 5% increase in cancer risk.
Particularly striking, according to Mr. Malmborg, was the MI survivors’ 44% increased relative risk for lung cancer and 31% increase in bladder cancer during the period from 6 months–17 years post-MI compared with the general population. In contrast, rates of breast, prostate, and colon cancer weren’t significantly different between MI survivors and the general population with no history of MI.
This observational study didn’t address the mechanisms involved in MI survivors’ increased cancer risk. Although the Danish registry didn’t include information of smoking status, Mr. Malmborg speculated that smoking may figure prominently, since it is a major shared risk factor for cardiovascular disease as well as lung and bladder cancer in particular. Other shared risk factors for cardiovascular disease and cancer include obesity, sedentary lifestyle, and excessive alcohol use.
This is the first large-scale study to look at cancer risk post-MI. It’s an increasingly relevant issue because the advances in cardiac care that have brought improved long-term survival following acute MI means more patients with a history of MI are likely to die from noncardiac causes, Mr. Malmborg observed.
He and his coinvestigators are now performing a number-needed-to-screen analysis to help them determine whether structured, formal creening for cancer following an MI should be done routinely.
The study was supported by Danish national medical research funds. The presenter reported having no financial conflicts.