Primary Cardiac Sarcoma: Clinical Characteristics and Prognostic Factors Over the Past 2 Decades.

Background: Primary cardiac sarcomas (PCS) are extremely rare malignant tumors involving the heart. Only isolated case reports have been described. There is a paucity of data on the epidemiological characteristics of PCS. This study has the objective of investigating the epidemiologic characteristics, survival outcomes, and independent prognostic factors of PCS. Methods: We enrolled a total of 362 patients with PCS, between 2000 and 2017, by retrieving the Surveillance, Epidemiology, and End Results (SEER) database. We analyzed demographics, clinical characteristics, and overall mortality (OM) as well as cancer-specific mortality (CSM) of PCS. Variables with a p-value < 0.1 in the univariate Cox regression were incorporated into the multivariate Cox model to determine the independent prognostic factors, with a hazard ratio (HR) of greater than 1 representing adverse prognostic factors. Results: Crude analysis revealed a high OM in age 80+ (HR=5.958, 95% CI 3.357-10.575, p=0), followed by age 60-79 (HR=1.429, 95% CI 1.028-1.986, p=0.033); and PCS with distant metastases (HR=1.888, 95% CI 1.389-2.566, p=0). Patients that underwent surgical resection of the primary tumor and patients with malignant fibrous histiocytomas (HR=0.657, 95% CI 0.455-0.95, p=0.025) had a better OM (HR=0.606, 95% CI 0.465-0.791, p=0). The highest cancer-specific mortality was observed in age 80+ (HR=5.037, 95% CI 2.606-9.736, p=0) and patients with distant metastases (HR=1.953, 95% CI 1.396-2.733, p=0). Patients with malignant fibrous histiocytomas (HR=0.572, 95% CI 0.378-0.865, p=0.008) and those who underwent surgery (HR=0.581, 95% CI 0.436-0.774, p=0) had a lower CSM. Multivariate Cox proportional hazard regression analyses revealed higher OM in the age group 80+ (HR=13.261, 95% CI 5.839-30.119, p=0) and advanced disease with distant metastases (HR=2.013, 95% CI 1.355-2.99, p=0.001). Lower OM was found in patients with rhabdomyosarcoma (HR=0.364, 95% CI 0.154-0.86, p=0.021) and widowed patients (HR=0.506, 95% CI 0.263-0.977, p=0.042). Multivariate Cox proportional hazard regression analyses of CSM also revealed higher mortality in the same groups, and lower mortality in patients with Rhabdomyosarcoma. Conclusion: In this United States population-based retrospective cohort study using the SEER database, we found that cardiac rhabdomyosarcoma was associated with the lowest CSM and OM. Furthermore, as expected, age and advanced disease at diagnosis were independent factors predicting poor prognosis. Surgical resection of the primary tumor showed lower CSM and OM in the crude analysis but when adjusted for covariates in the multivariate analysis, it did not significantly impact the overall mortality or the cancer-specific mortality. These findings allow for treating clinicians to recognize patients that should be referred to palliative/hospice care at the time of diagnosis and avoid any surgical interventions as they did not show any differences in mortality. Surgical resection in patients with poor prognoses should be reserved as a palliative measure rather than an attempt to cure the disease.