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 in the literature over different periods of time. This pathology has been associated with a dismal prognosis and given its rarity; treatment options are very limited. Furthermore, there are contrasting data about the effectiveness of current treatment modalities in improving the survival of patients with PCS, including surgical resection which is the mainstay of therapy. 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: A total of 362 patients were ultimately registered in our study from the Surveillance, Epidemiology, and End Results (SEER) database. The study period was from 2000 to 2017. Demographics such as clinical characteristics, overall mortality (OM), and PCS-specific mortality (CSM) were taken into account. A p value of <0.1 in the univariate analysis leads to the incorporation of the variable into multivariate analysis adjusting for covariates. Adverse prognostic factors were represented by a Hazard Ratio (HR) greater than one. The five-year survival analysis was carried out using the Kaplan-Meier method and the log-rank test was used to compare survival curves.

Results: Crude analysis revealed a high OM in age 80+ (HR = 5.958, 95% CI 3.357-10.575, p < 0.001), 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 < 0.001). 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 < 0.001). The highest cancer-specific mortality was observed in age 80+ (HR = 5.037, 95% CI 2.606-9.736, p < 0.001) and patients with distant metastases (HR = 1.953, 95% CI 1.396-2.733, p < 0.001). 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 < 0.001) had a lower CSM. Patients in the age range 80+ (HR = 13.261, 95% CI 5.839-30.119, p < 0.001) and advanced disease with distant metastases (HR = 2.013, 95% CI 1.355-2.99, p = 0.001) were found to have a higher OM in the multivariate analyses adjusting for covariates). 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 of 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, adjuvant chemotherapy, and/or radiation in patients with poor prognoses should be reserved as palliative measures rather than an attempt to cure the disease.