Dr. Michael J. Reardon on Cardiac Angiosarcoma
Dr. Michael J. Reardon, surgeon at Houston's Methodist Debakey Heart Center, answers questions on cardiac angiosarcoma.
What is the prevalence of cardiac angiosarcoma?
Cardiac tumors occur as primary tumors or tumors that arise from the heart tissues themselves or secondary tumors which are tumors that have spread (metastasized) to the heart. Secondary tumors are 20-40 times more prevalent than primary tumors. Of the primary tumors, 75% are benign and 25% are malignant. Of the malignant tumors, about 75% are sarcomas. Primary malignant tumors of the heart occur about 1 in 10,000 people. Angiosarcomas are the most frequent cardiac sarcoma occurring.
What advice would you offer people newly diagnosed with cardiac angiosarcoma?
Cardiac tumors are rare and malignant cardiac tumors such as angiosarcoma are even less common. Because of their rarity, few individual physicians acquire much experience in their treatment. My best advice is to seek out institutions and physicians in these institutions with a reasonable level of experience in dealing with this disease.
Why is a clinical diagnosis of cardiac angiosarcoma usually difficult?
Tumors of the heart are difficult to diagnose because they usually do not cause symptoms. This is because the heart does not experience pain from the tumor itself. Symptoms usually occur when the tumor is large enough to obstruct blood flow through the heart, which causes heart failure. A piece breaks off the tumor and embolizes (travels through the blood stream) to another location that causes symptoms (stroke or lack of blood flow to a limb, etc.) or obstructs a coronary artery and causes angina or interferes with the conduction system causing heart block and a slow heart rate. These symptoms, when they occur, are usually not present until the tumor is relatively advanced.
What is an autotransplant surgery of the heart and what types of cardiac angiosarcoma patients could benefit from such surgery? Will metastasis to other organs affect success of this type of surgery?
Autotransplant of the heart is a technique where the heart is completely removed from the chest and then reimplanted. It was first used as a means of completely denervating (severing all nerves) the heart for people with variant angina (angina caused by microvessels and not amenable to angioplasty or coronary bypass). This did relieve the angina (chest pain) but the lack of blood flow persists and the patients just died with silent heart attacks. There was also a high surgical mortality for the procedure at the time it was performed. Improvement in surgical techniques and the ability to protect the heart during surgery have allowed ever more complex surgical procedures to be done with good success. For sarcoma of the heart, success depends on complete removal at the time of surgery with precise reconstruction of the heart. This has been particularly difficult in large sarcomas of the left atrium. The left atrium is the heart chamber that is directly in back of the heart and visualization for surgical procedures is somewhat limited compared to the anterior (front) chambers of the heart. Autotransplant as an approach to left atrial sarcoma allows the surgeon to remove the heart and turn it over so that the posterior (back) left atrium now becomes the anterior (front) portion of the heart. This allows direct visualization of the tumor for complete resection and precise reconstruction prior to reimplanting the heart.
At what stage of treatment would you recommend autotransplant surgery of the heart for cardiac angiosarcoma patients?
If there is no evidence of metastatic disease and the tumor is large or on the anterior (front) wall of the left atrium, then autotransplantation can be considered early. Cardiac transplantation has become a standard approach, and yields good results, for some patients with end-stage heart failure. However, there are several problems. (1) There is a severe lack of donor hearts to use for transplantation and only about 10% of those who might benefit from cardiac transplantation actually get a heart; therefore, the patient with a cardiac malignancy must compete with many others without malignant disease while awaiting a heart. (2) In many parts of the country waiting time to get a heart transplant is often 3-4 months due to lack of donor availability. For patients with large tumors and congestive heart failure from blockage of blood flow to the heart, this time may not be available. (3) Standard transplantation requires significant immunosuppression to prevent rejection, which both impacts one's quality of life and has an unknown effect on the tumor's ability to grow if it metastasizes.
Why is autotransplant surgery recommended over a donor heart transplant?
Autotransplant does not require a donor heart, a lengthy wait, or immunosuppression, but still permits the surgical goal of complete resection in appropriate patients.
What role does surgery play in the treatment of cardiac angiosarcoma and how might chemotherapy, surgery, and other therapies work together to create the best possible outcome for the patient?
Angiosarcomas usually occur on the right side of the heart or in the pericardium. Autotransplantation is usually not necessary or appropriate for tumors in this location because they are easy to visualize. Surgery allows the best approach for tumors without metastatic spread, and which are confined to portions of the heart that are completely resectable. These tumors are often complex, and experience gained in transplantation, autotransplantation, complex cardiac valve procedures and congenital heart surgery has aided in our approach to complete resection. Unfortunately, angiosarcomas have a tendency to metastasize early. In this case it is a systemic disease (as opposed to local in the heart only) and needs a systemic approach such as chemotherapy. Chemotherapy alone has not enjoyed great success with angiosarcomas, but we do combine it with any surgical procedures we do as an adjuvant. The eventual cure of this terrible disease will be a biologic approach to the tumor itself. We and others are currently actively engaged in developing targeted biological solutions for sarcomas.
What is angiogenesis and what role is it playing in cancer treatment for sarcoma patients? Angiogenesis literally means growing of new blood vessels. No tissue in the body can live further than 200 microns from a blood vessel as this is the diffusion capacity of oxygen which is necessary to sustain cellular metabolism. For tumors to grow (or for their metastasis to grow) they must grow their own new blood vessels. This is done through elaboration of compounds such as VEGF (vascular endothelial growth factor). Where angiosarcomas and cancer become linked in potential treatment is through compounds that do the opposite and inhibit new blood vessel growth such as angiostatin and endostatin. These are the subject of on-going clinical trials at this time.
Is there any other advice you would like to share with families affected by cardiac angiosarcoma? Cardiac sarcomas are complex and unusual diseases. Their treatment should optimally be done in institutions with an interest in and large volume of cancer cases and by cardiac surgeons with experience in this area. Because of the rarity, few cardiac surgeons develop a significant experience with cardiac sarcomas. Families should inquire about both institution and individual experience when making a decision.