Cardiac tumors are rare, with an autopsy frequency of 0.001% to 0.30%; in one report, the percentage of cardiac surgeries performed as a result of cardiac tumors was 0.093%.

The most common primary tumors of the heart are benign and include the following:

• Rhabdomyoma.
• Myxoma.
• Teratoma.
• Fibroma.

Other benign tumors include histiocytoid cardiomyopathy tumors, hemangiomas, and neurofibromas (i.e., tumors of the nerves that innervate the muscles).

Myxomas are the most common noncutaneous finding in Carney complex, a rare syndrome characterized by lentigines, cardiac myxomas or other myxoid fibromas, and endocrine abnormalities. A mutation of the PRKAR1A gene is noted in more than 90% of the cases of Carney complex.

Primary malignant pediatric heart tumors are rare and include the following:

• Malignant teratoma.
• Lymphoma.
• Various sarcomas, including rhabdomyosarcoma, angiosarcoma, undifferentiated pleomorphic sarcoma, leiomyosarcoma, chondrosarcoma, synovial sarcoma, and infantile fibrosarcoma.

Secondary tumors of the heart include metastatic spread of rhabdomyosarcoma, other sarcomas, melanoma, leukemia, thymoma, and carcinomas of various sites.

Do a Google or PubMed search for “cardiac tumor,” and your results will be littered with individual case reports and little more. There are no clinical trial results, meta-analyses, or treatment guidelines.

Because, although the heart may be the ultimate emblem of love, compassion, and chocolate-themed holidays, it also has another distinction: a near immunity to cancer. And given the heart’s importance in the body, that’s a fortunate fact of life.

However, it does raise the question: Why is this large and infinitely important component of anatomy such an inhospitable host to the leading cause of mortality for those aged 85 and younger? The answer, it appears, can be found in the highly specialized and most abundant cell in this muscle-laden organ, the cardiac myocyte.

Few, but Deadly

Cardiac primary tumors, those originating in the heart itself, are extremely rare. In published autopsy series, the high-end incidence of such tumors is about one quarter of one percent. The majority of diagnosed cardiac tumors are benign. In adults, a somewhat mushy, gelatinous type of tumor called a myxoma is the most common; in infants and children, rhabdomyomas predominate, typically associated with the syndrome tuberous sclerosis.

According to Dr. Robert J. Cusimano, a cardiac surgeon at Toronto General Hospital, malignant heart tumors are most often metastases from primary tumors in nearby organs, such as the kidneys or lungs.

“If there are metastases to the heart, the prognosis is pretty bad,” said Dr. Cusimano, who lightheartedly refers to himself as a “cardiac oncologist,” because patients with these tumors are often referred to him. Even then, his entire division may see only 12 benign tumors in a given year. He is personally involved with about 5 to 10 cardiac cancer cases per year, of which one or two are primary malignancies.

Angiosarcomas are the most common malignant primary cardiac tumor. According to published case reports, including one co-authored by Dr. Cusimano, using chemotherapy and/or radiotherapy to shrink the primary tumor and eliminate any micrometastases followed by surgery to remove the primary tumor has had some success.

The Tell-Tale Cell

Unlike other damaged organs, the heart seems mostly incapable of mending injured tissue. And that, according to leading cardiac researchers, is because the cells that compose the muscle itself, cardiac myocytes, are terminally differentiated.

In other words, these cells reach a point very early on in a person’s life where they permanently exit the cell cycle and stop dividing. After that, further growth occurs by expansion in cell size, not through cell division. This differs, for instance, from the epithelial cells that line other organs, which, in response to certain stimuli, actively divide and, when necessary, grow in number.

This “very tight cell cycle control of cardiomyocytes” acts as a double-edged sword, explained Dr. Deepak Srivastava, director of the Gladstone Institute of Cardiovascular Disease at the University of California, San Francisco. Not only does it “prevent them from ever re-entering the cell cycle to proliferate and repair damaged tissue,” but it may also explain why “they are so resistant to tumor formation,” he said.

With so little proliferative activity, added Dr. John E. Tomaszewski, from the Department of Pathology and Laboratory Medicine at the University of Pennsylvania Medical School, “the opportunity for abnormalities in cell cycle kinetics which characterizes tumors in so many other body sites is just not an issue in the heart.”

Given their extreme rarity, there is little in the way of any organized effort to further research on how and why cardiac tumors arise or how best to treat them. For now, Dr. Cusimano believes, the wisest avenue to help improve outcomes is to funnel patients to centers that have experience treating patients with cardiac tumors.

Routinely sending patients to these hospitals will ensure that “surgeons and oncologists can get more experience with these cases,” Dr. Cusimano said. “That’s the only way we can move forward with these types of cancers.”

Childhood cardiac tumors, which may be benign or malignant, form in the heart.

Most tumors that form in the heart are benign (not cancer). Benign heart tumors that may appear in children include the following:

• Rhabdomyoma: A tumor that forms in muscle made up of long fibers.
• Myxoma: A tumor that may be part of an inherited syndrome called Carney complex.
• Teratomas: A type of germ cell tumor. In the heart, these tumors form most often in the pericardium (the sac that covers the heart). Some teratomas are malignant (cancer).
• Fibroma: A tumor that forms in fiber-like tissue that holds bones, muscles, and other organs in place.
• Histiocytoid cardiomyopathy tumor: A tumor that forms in the heart cells that control heart rhythm.
• Hemangiomas: A tumor that forms in the cells that line blood vessels.
• Neurofibroma: A tumor that forms in the cells and tissues that cover nerves.

Before birth and in newborns, the most common benign heart tumors are teratomas. An inherited condition called tuberous sclerosis can cause heart tumors to form in an unborn baby (fetus) or newborn.

Malignant tumors that begin in the heart are even more rare than benign heart tumors in children. Malignant heart tumors include:

• Malignant teratoma.
• Lymphoma.
• Rhabdomyosarcoma: A cancer that forms in muscle made up of long fibers.
• Angiosarcoma: A cancer that forms in cells that line blood vessels or lymph vessels.
• Undifferentiated pleomorphic sarcoma: A cancer that usually forms in the soft tissue, but it may also form in bone.
• Leiomyosarcoma: A cancer that forms in smooth muscle cells.
• Chondrosarcoma: A cancer that usually forms in bone cartilage, but very rarely can begin in the heart.
• Synovial sarcoma: A cancer that usually forms around joints, but may very rarely form in the heart or sac around the heart.
• Infantile fibrosarcoma: A cancer that forms in fiber-like tissue that holds bones, muscles, and other organs in place.

When cancer begins in another part of the body and spreads to the heart, it is called metastatic cancer. Some types of cancer, such as sarcoma, melanoma, and leukemia, start in other parts of the body and spread to the heart. This summary is about cancer that first forms in the heart, not metastatic cancer.

Signs and symptoms of a heart tumor include a change in the heart's normal rhythm and trouble breathing.

These and other signs and symptoms may be caused by heart tumors or by other conditions.

Check with your child's doctor if your child has any of the following:

• Change in the heart's normal rhythm.
• Trouble breathing, especially when the child is lying down.
• Pain or tightness in the middle of the chest that feels better when the child is sitting up.
• Coughing.
• Fainting.
• Feeling dizzy, tired, or weak.
• Fast heart rate.
• Swelling in the legs, ankles, or abdomen.
• Feeling anxious.
• Signs of a stroke.
  • Sudden numbness or weakness of the face, arm, or leg (especially on one side of the body).
  • Sudden confusion or trouble speaking or understanding.
  • Sudden trouble seeing with one or both eyes.
  • Sudden trouble walking or feeling dizzy.
  • Sudden loss of balance or coordination.
  • Sudden severe headache for no known reason.

Sometimes heart tumors do not cause any signs or symptoms.

Tests that examine the heart are used to diagnose a heart tumor.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Echocardiogram: A procedure in which high-energy sound waves (ultrasound) are bounced off the heart and nearby tissues or organs and make echoes. A moving picture is made of the heart and heart valves as blood is pumped through the heart.
• Electrocardiogram (EKG): A recording of the heart's electrical activity to check its rate and rhythm. A number of small pads (electrodes) are placed on the patient’s chest, arms, and legs, and are connected by wires to the EKG machine. Heart activity is then recorded as a line graph on paper. Electrical activity that is faster or slower than normal may be a sign of heart disease or damage.
• Cardiac catheterization: A procedure to look inside the blood vessels and heart for abnormal areas or cancer. A long, thin, catheter is inserted into an artery or vein in the groin, neck, or arm and threaded through the blood vessels to the heart. A sample of tissue may be removed using a special tool. A pathologist views the tissue under a microscope to look for cancer cells.

The process used to find out if malignant heart tumors (cancer) have spread from the heart to nearby areas or other parts of the body is called staging. There is no standard staging system for malignant childhood heart tumors. The results of tests and procedures done to diagnose malignant heart tumors are used to help make decisions about treatment.

Sometimes malignant childhood heart tumors recur (come back) after treatment.

Treatment Option Overview

KEY POINTS

• There are different types of treatment for children with heart tumors.
• Children with heart tumors should have their treatment planned by a team of doctors who are experts in treating childhood cancer.
• Five types of treatment are used:
  • Watchful waiting
  • Chemotherapy
  • Surgery
  • Radiation therapy
  • Targeted therapy
• New types of treatment are being tested in clinical trials.
• Treatment for childhood heart tumors may cause side effects.
• Patients may want to think about taking part in a clinical trial.
• Patients can enter clinical trials before, during, or after starting their cancer treatment.
• Follow-up tests may be needed.

There are different types of treatment for children with heart tumors.

Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Because cancer in children is rare, taking part in a clinical trial should be considered. Some clinical trials are open only to patients who have not started treatment.

Children with heart tumors should have their treatment planned by a team of doctors who are experts in treating childhood cancer.

Treatment of malignant heart tumors will be overseen by a pediatric oncologist, a doctor who specializes in treating children with cancer. The pediatric oncologist works with other pediatric health professionals who are experts in treating children with cancer and who specialize in certain areas of medicine. This may include the following specialists and others:

• Pediatrician.
• Pediatric heart surgeon.
• Pediatric cardiologist.
• Radiation oncologist.
• Pathologist.
• Pediatric nurse specialist.
• Social worker.
• Rehabilitation specialist.
• Psychologist.
• Child-life specialist.

Five types of treatment are used:

Watchful waiting

Watchful waiting is closely monitoring a patient's condition without giving any treatment until signs or symptoms appear or change. This treatment may be used for rhabdomyoma.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy).

Surgery

When possible, the cancer is removed by surgery. Types of surgery that may be done include the following:

• Surgery to remove the tumor and some healthy tissue around it.
• Heart transplant. If the patient is waiting for a donated heart, other treatment is given as needed.

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. External radiation therapy uses a machine outside the body to send radiation toward the area of the body with cancer.

Targeted therapy

Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells. Targeted therapies usually cause less harm to normal cells than chemotherapy or radiation therapy do.

• mTOR inhibitor therapy: These drugs stop cells from dividing and may prevent the growth of new blood vessels that tumors need to grow. Everolimus is used to treat children who have rhabdomyoma and tuberous sclerosis.

Targeted therapy is also being studied for the treatment of malignant childhood heart tumors that have recurred (come back).

New types of treatment are being tested in clinical trials.

Information about clinical trials is available from the NCI website.

Treatment for childhood heart tumors may cause side effects.

Side effects from cancer treatment that begin after treatment and continue for months or years are called late effects. Late effects of cancer treatment may include:

• Physical problems.
• Changes in mood, feelings, thinking, learning, or memory.
• Second cancers (new types of cancer) or other conditions.

Some late effects may be treated or controlled. It is important to talk with your child's doctors about the possible late effects caused by some treatments.

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Follow-up tests may be needed.

Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your child's condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.

Treatment of Childhood Heart Tumors

Treatment of newly diagnosed childhood heart tumors may include the following:

• Watchful waiting, for rhabdomyoma, which sometimes shrinks and goes away on its own.
• Targeted therapy (everolimus) for patients who have rhabdomyoma and tuberous sclerosis.
• Chemotherapy followed by surgery (which may include removing some or all of the tumor or a heart transplant), for sarcomas.
• Surgery alone, for other tumor types.
• Radiation therapy for tumors that cannot be removed by surgery.

Treatment of Recurrent Childhood Heart Tumors

Treatment of malignant recurrent childhood tumors may include the following:

• A clinical trial that checks a sample of the patient's tumor for certain gene changes. The type of targeted therapy that will be given to the patient depends on the type of gene change.