Cancer patients have higher cardiovascular mortality risk

Main cause of death in cancer survivors is heart disease and not recurrence of cancer


Ramya was having a particularly good day. After fighting breast cancer with chemotherapy and surgery, she had it under control. She believed she was through the worst. But the reports from the doctor later that week brought up new concerns. Her heart was getting weaker, and it was due to the potentially life-saving drug that she was taking to prevent the cancer from spreading. Her medical team stopped the drug. Presently, Ramya is waiting to see if her heart will get better so that she can resume the drug. This could damage her heart all over again and so she and her family have to decide if they want to take the risk.

Thousands of cancer patients are confronting similar dilemmas because their treatment may also cause heart problems, either immediately or down the road. Women like Ramya face a tough choice: stay on a miracle drug that might damage their heart, or stop the drug and risk having the cancer spread.

Cancer patients have a 2–6 times higher cardiovascular mortality risk than the general population, and cardiovascular mortality is evident throughout the time of cancer care. The number one cause of death in cancer survivors is heart disease and not the recurrence of cancer. This evidence has led to the explosion of a new field of interest―cardio-oncology, in the last decade.

“Cardio-oncology represents the intersection between heart and cancer. We know that both traditional and new therapies of cancer can have adverse effects on the heart. We are seeing that people who live longer with their cancer or in some cases are cured have heart disease because of the effect of the drug or since heart disease is the most common cause of death globally. But we have to recognise there are new issues after the cancer treatment, and that the risk is much greater than in the general population,” says Dr Javid Moslehi, chief, cardio-oncology and immunology section, UCSF (University of California San Francisco).

In some cases, the dangerous effects are spotted quickly. But they can take decades to surface, as seen in survivors of some childhood cancers.

A small section of the field of cardio-oncology is dedicated to diagnosing and managing primary or secondary tumours of the heart. A majority of the field focuses on cardio-toxicity from radiation therapy, chemotherapy and immunotherapy. While anthracyclines (a class of drugs used in chemotherapy) are frequently associated with heart disease, a myriad of new chemotherapy and immunotherapy drugs have shown diverse cardiovascular effects. Not only can people develop cancer treatment-related cardiac dysfunction (CTRCD)―the decreased ability of the left ventricle to pump blood effectively, which may lead to heart failure―they can also develop any number of other heart problems including hypertension, arrhythmia, inflammation of the pericardium (the sac-like membrane surrounding the heart) or progressive coronary artery disease.

In some cases, the dangerous effects are spotted quickly. But they can take decades to surface, as seen in survivors of some childhood cancers. Paediatric oncologists began sounding the alarm 20 years ago, when they saw heart problems among patients who had beaten cancer as children. Although modern cancer treatments for children, such as chemotherapy and radiotherapy, have improved over time and are now often given in lower but still-effective doses, new and long-term survivors should know about the possibility of what’s called “late effects” of treatment.

In addition to children, women and adults aged 60 and above are considered at higher risk for cardio-toxic side-effects. The following health concerns are associated with the development or worsening of cardiovascular disease in general and may dramatically increase the risk of cardiac injury from cancer therapy:

◆ Smoking

◆ Diabetes

◆ Hypertension

◆ High cholesterol

◆ Obesity

◆ Pre-existing heart problems These cancer therapies are associated with cardio-toxic side-effects:

◆ Anthracyclines (chemotherapy)

◆ Trastuzumab (breast cancer medication)

◆ Checkpoint inhibitors (immunotherapy drugs)

◆ High-dose chest radiation

◆ Some targeted therapies such as tyrosine kinase inhibitors

Catching cardiac problems that arise early is key. Cardio-oncologists can implement strategies to prevent certain cardiac conditions from becoming worse. In some cases, they can even help heal prior damage.

Pratap had Hodgkin’s lymphoma, cancer of the lymph-node system, when he was in his late 20s. He had radiation therapy along with chemotherapy to control his cancer. Thirty years later, doctors found problems with two of his heart valves and he is scheduled for surgery. Pratap’s cardiologist says his heart problems are the result of radiation he received 30 years ago. The radiation caused scar tissue to form, making the heart valves rigid.

As the numbers of survivors grow, so does the number of patients living with late effects of cancer-related cardio-toxicity. For example, among Hodgkin's lymphoma patients who have received radiation, cardiovascular disease is a major cause of death. Many cancer patients are vigilant about getting checked for cancer, but ignore potentially greater risks they face with their heart.

Over the last decade, the awareness that cancer care can directly result in cardiac complications is growing, as is the understanding that patients who have survived cancer have an increased risk of dying from heart failure, coronary heart disease and stroke.

Unfortunately, within cancer centres, allotment of resources towards cardiovascular evaluation and testing may not be seen as a priority. With evidence mounting on the link between cancer survival and cardiovascular disease, it is essential that a priority be placed on incorporating cardio-oncology specialists into the cancer care treatment model.

Some patients beset by cancer and heart issues manage to survive both. Meena, 48, with a history of lymphoma, had received a cardio-toxic drug―doxorubicin (also known as adriamycin)―about 20 years ago for breast cancer. She needed to use this medication a second time in order to cure her lymphoma. Her heart function was already abnormal, likely because of the earlier treatment with doxorubicin. Her oncologist consulted a cardio-oncologist because there was concern that her heart function would worsen with further doxorubicin treatment. She was recommended cardio-protective medications and cardiovascular management during cancer therapy. She was followed closely and was able to safely make it through her lymphoma treatment. Now, five years later, she remains alive and well, with heart function that is mildly abnormal but very stable.

Given oncology’s fast pace of cancer care and changes in treatment paradigm, it is imperative for oncologists to work closely with subspecialists and keep abreast of the most current information, data, potential side-effects and updated screening protocols that may impact patients.

Because of improved cancer screenings, early detection and screening, people are living longer after a cancer diagnosis; and increasing numbers of patients are cured of their cancer. With further improvement in cancer therapy, this number will continue to increase in years to come. Cardio-oncology needs to be a universal subspecialised group of physicians in all health care organisations and medical institutions. The need is growing. The availability of solutions needs to grow at the same pace.

Priya Menon is host and producer of CureTalks, an international online talk show discussing medical breakthroughs, research and treatments.