Clinical Pearls & Morning Reports
Published January 2, 2019
Radiation-associated tumors typically arise within direct radiation fields, but they could arise adjacent to a radiated field. Read the latest NEJM Clinical Problem-Solving article here.
Q: What is the most common primary malignant cardiac tumor?
A: Primary cardiac tumors are extremely rare, accounting for less than 0.02% of all cardiac neoplasms. Approximately 75% of these tumors are benign, most often atrial myxomas or fibroelastomas. Sarcomas account for nearly 95% of all malignant primary cardiac tumors, followed by primary cardiac lymphomas and mesotheliomas. The most common cardiac sarcomas are angiosarcomas and intimal or unclassified sarcomas.
Q: Is a tumor on the right side of the heart more likely to be benign or malignant?
A: Angiosarcomas tend to arise from the right side of the heart, whereas other cardiac sarcomas arise from the left side of the heart. A majority of myxomas arise from the left atrium and are attached to the interatrial septum. Thus, the finding of a nonthrombotic cardiac mass on the right side of the heart increases concern for a malignant tumor.
A: Treatment of primary cardiac sarcomas is guided by anatomical location. Sarcomas on the right side of the heart are often large, bulky, and infiltrative with early metastases, often to the lungs. Sarcomas on the left side of the heart are frequently misdiagnosed initially as myxomas, which often grow into the left atrium and cause obstructive symptoms and heart failure. Primary pulmonary-artery sarcomas and intimal sarcomas can manifest with obstruction of the pulmonary artery and failure of the right side of the heart and may be mistaken for a pulmonary embolus. Without resection, mortality at 1 year approaches 90%, but even with resection, outcomes are poor; in one study, 1-year mortality was 35%, and in another study, the median survival was 15 months after surgery. Treatment consists of surgical resection, which may offer symptomatic relief and in rare instances, cure. The use of adjuvant chemotherapy after resection is controversial; limited data relevant to postoperative management of cardiac sarcomas are available.
A: Radiation-associated sarcomas account for less than 5% of all sarcomas and, as with other forms of sarcoma, are generally considered to have a poor prognosis. The most common histologic types of radiation-associated sarcoma are angiosarcoma and unclassified sarcoma. Most radiation-associated angiosarcomas and a subset of radiation-associated unclassified sarcomas show MYC amplification, which is not seen in sarcomas that are not associated with radiation. A sarcoma is considered to be radiation-associated if the patient was previously exposed to radiation treatment and the sarcoma was not present before the onset of the exposure, if the sarcoma has developed within or adjacent to a previously irradiated field (within the 5% isodose line of the radiation field), and if the sarcoma is histologically distinct from the primary tumor. Radiation-associated sarcomas usually develop years after radiation therapy. Radiation treatment for breast cancer is the most common contributor to radiation-related sarcomas owing to the prevalence of breast cancer and the favorable survival rate after breast-cancer treatment.