The Heart Bone is Connected to the Cancer Bone: New Data and More Concern
As if it was not enough grief for the approximate 15 million Americans and millions more worldwide diagnosed with cancer and who have to deal with all those issues, but there is a growing appreciation that the heart is not an innocent bystander or participant in cancer therapy. A relatively new discipline called cardio-oncology has developed and many medical centers now have clinics dedicated to monitoring the heart function of patients treated for cancer recently or long ago.
It has been appreciated for several decades that certain agents used to treat cancer can harm the heart. The classic example is doxorubicin used for leukemia, breast cancer, lymphoma and other cancers. This agent can cause irreversible damage to the heart leading to congestive heart failure. Newer agents, such as trastuzumab (Herceptin) used in some breast cancer and gastric cancer patients often with Adriamycin (doxorubicin), can also cause heart damage that is usually reversible. Other agents like sunitinib used for kidney cancer can cause hypertension. Recommendations for the monitoring of heart function during therapy have been developed and are common practice. Monitoring for even early signs of heart damage using laboratory testing is emerging as a hopeful area.
More recently, strategies to prevent the damage induced by these agents has been studied. Medications known to protect the heart like certain beta-blockers and ACE inhibitors are showing promise both for the prevention and early therapy of heart injury during chemotherapy. A final area of concern is radiation therapy often used alone or with chemotherapy. Women who receive radiation therapy, particularly over the left breast which sits above the heart, have in increased risk of both congestive heart failure and accelerated coronary artery disease. The risk to heart arteries may exist for up to 20 years after the initial radiation treatment given. Integrative strategies including supplements like coenzyme Q10, diets that include fasting, and other nutritional approaches are being studied.
As many patients receiving therapy for cancer are in their middle ages or beyond, the risk of silent heart disease, particularly coronary artery disease (CAD), is at least as high as the public at large. CAD is increased in survivors of breast cancer therapy, and nearly as many women will die of heart disease heart issues as will die of their breast cancer itself in follow up. Adult patients with cancer may benefit from a thorough evaluation for risk factors for CAD and the presence of silent heart disease using cardiac CT or carotid ultrasound. In many cases, review of chest and abdominal CT scans done for cancer staging may reveal silent calcified arteries that indicates and increased concern for important CAD.
The final area of overlap between oncology and cardiology is the late survivorship of cancer patients in terms of the effects of chemotherapy. Patients with breast cancer and lymphoma who have received agents like doxorubicin and those who have had radiation to their chest are candidates for long-term monitoring for the late development of damage. An echocardiogram at 5 years in patients with heart risk factors and at 10 years in all other patients, along with a stress test and heart CT scan should be considered and has been recommended to search for late heart damage and CAD.
New Studies on Late Heart Disease
- A recently published medical review in women treated with breast cancer showed that anthracycline-containing chemotherapy plus irradiation of the internal mammary chain (IMC) was associated with a heart failure (CHF) risk nine times greater than that of women in the general population. Anthracycline therapy alone increased heart failure risk four times over that of the general population. IMC irradiation also increased the risk of ischemic heart disease (IHD) and valvular heart disease (VHD), regardless of whether the radiation treatment was on the right or left side. In many instances, the CVD risk did not emerge for 20 years or more after treatment for breast cancer, they reported in the British Journal of Cancer.
- Another recent study showed a dose-dependent association between irradiation for breast cancer and the risk of injury to the left ventricle (LV) and coronary artery segments. Covering a 43-year period beginning in 1958, the data suggested that all coronary segments “are sensitive to radiation and that doses to all segments should be minimized,” authors wrote in the Journal of Clinical Oncology.
There is much work to do to bring oncologists and cardiologists together for the optimal prevention, planning, treatment, and follow-up of patients at risk for or diagnosed with cancer. It may be advisable to seek out such a specialist in your community, whether bearing a MD, DO, or ND degree, to optimize the chances of a short-term and long-term freedom of heart disease and CAD after cancer therapy.