Increased cancer risk after myocardial infarction: fact or fiction? A systemic review and meta-analysis.

Objective: Accumulating evidences showed some positive relations between myocardial infarction (MI) and new onset cancer. We aim to investigate whether MI is associated with an increased risk of incident cancer. Methods: A comprehensive literature list was identified from MEDLINE, Embase, and Web of Science databases from inception until October 2018. The main inclusion criteria included observational studies investigating the association between MI and new onset cancer. Stata 12.0 software was used for meta-analysis. Results: Of 862 potentially relevant studies, five cohort studies met all inclusion criteria. The pooled cancer incidence rate was 9.5% (95% CI=8.3-10.7%). Pooled analysis of OR showed that the increased overall cancer risk in MI patients in comparison with controls had no statistical significance (OR=1.08; 95% CI=0.97-1.19, P=0.153). Subgroup analysis by gender demonstrated that the overall cancer risk was only significantly increased in female (OR=1.10; 95% CI=1.01-1.20, P=0.025), but not in male patients (OR=1.04; 95% CI=0.99-1.10, P=0.124). In terms of cancer type, the increased cancer risk was only significant for lung cancer (male OR=1.12; 95% CI=1.05-1.19, P<0.01; and female OR=1.51; 95% CI=1.15-1.99, P<0.01), but not for prostate (OR=0.96; 95% CI=0.85-1.09, P=0.546) or breast cancer (OR=0.94; 95% CI=0.86-1.04, P=0.222). In addition, the increased cancer risk was only significant in the first 6 months (OR=1.93; 95% CI=1.42-2.63, P<0.01) but not in 6 months-1-year (OR=1.03; 95% CI=0.92-1.15, P=0.627) or >1-year (OR=0.98; 95% CI=0.93-1.04, P=0.585) follow-up after MI. Conclusion: From available evidence, the increased overall cancer risk after MI was only significant in female but not in male patients. Besides, the increased cancer risk could be driven by increased short-term cancer incidence after MI and certain cancer types such as lung cancer.