Prevalence of primary cardiac tumor malignancies in retrospective studies over six decades: a systematic review and meta-analysis

The incidence of patients diagnosed with primary malignant cardiac tumors (PMCTs) has increased greatly in the past few decades. Whether this rising prevalence is due to overdiagnosis or an increased malignancy rate of primary cardiac tumors (PCTs) remains unclear. Therefore, we performed a systematic review and meta-analysis of published retrospective studies to determine whether the malignancy rate has been increasing over time. Published studies containing relevant data between 1956 and 2014 were evaluated. Two authors searched for all retrospective studies that included patients diagnosed with PCT and PMCT. Two other investigators independently extracted the data, and discrepancies were resolved by consensus. A random-effects meta-analysis model and cumulative meta-analysis model were used to evaluate the pooled prevalence and trend of dynamic change in PCT malignancies. The effects of time, study period and sample size were studied using a logit-linear regression model with robust error variance and a time variable. Thirty-eight studies involving 5,586 patients were analyzed. The pooled prevalence of PMCT among the patients diagnosed with PCT was 9.9% (95% CI, 8.4% to 11.4%) (I2=70%; P< 0.001), and this prevalence has been stable since around 2003. In the regression model, the malignancy odds ratio remained stable from 1975 onward, and no time effect was observed. Our study confirms that PMCT is uncommon, and the prevalence of PCT malignancies remained stable in the past few decades. The clinically observed increase in incidence is unlikely to reflect a true population-level increase in tumorigenesis. This result strongly suggests that the observed increase in incidence of PMCT most likely reflects increased diagnostic detection over time.