May 21, 2008 — Childhood cancer survivors are at increased risk of developing premature cardiovascular disease, and hence need to be closely monitored after their treatment and followed appropriately as they age, concludes the largest and longest study of this population.
The findings are scheduled to be presented June 3 at the American Society of Clinical Oncology (ASCO) 2008 Annual Meeting, and were unveiled last week during a preview presscast organized by the society.
The study followed 14,358 survivors of various childhood cancers and compared them with 3,899 siblings. The diagnoses included childhood leukemia, central nervous system tumors, Hodgkin's and non-Hodgkin's lymphomas, renal tumors, neuroblastomas, soft-tissue sarcomas, and bone cancers. The average age of study participants at diagnosis was 7.8 years and the mean age at follow-up was 27.5 years, so the mean follow-up period was nearly 20 years.
The risk for cardiovascular disease was significantly greater in survivors than in siblings. The risk for atherosclerosis was 10 times greater, for congestive heart failure was 5.7 greater, for myocardial infarction was 4.9 times greater, for pericardial disease was 6.3 times greater, and for valvular disease was 4.8 times greater.
"This study shows that childhood cancer survivors in their 20s are developing the kinds of heart disease we typically see in older adults," commented lead investigator Daniel Mulrooney. MD, from the University of Minnesota, in Minneapolis. The risk for cardiovascular disease increased with time, and some of these problems appear quite late, he continued.
Cardiovascular monitoring of childhood cancer survivors should begin early and should be life-long.
"Cardiovascular monitoring of childhood cancer survivors should begin early and should be life-long," Dr. Mulrooney stated. He estimated that there are currently 270,000 childhood cancer survivors in the United States.
Long-Term Consequences of Cancer Treatment
Studies of childhood cancer survivors have identified long-term problems that can unfold as children grow into adulthood. In addition to cardiovascular problems, these include an increased risk for secondary cancers, infertility, lung scarring, thyroid problems, and psychological problems such as depression and anxiety, commented Julie Gralow, MD, from the University of Washington, in Seattle, who moderated the presscast.
Being a cancer survivor is a very special diagnosis in many ways.
"Being a cancer survivor is a very special diagnosis in many ways," Dr. Gralow commented, "and brings with it a responsibility to understand the long-term consequences of cancer treatment and to monitor these patients appropriately for any problems they may develop."
"Many patients, as they continue with their lives, tend to transfer their medical care to primary care physicians and to discontinue relationships with their oncologists, or maintain them very infrequently, as would be appropriate for someone who is...cured of their cancer," she continued. "But it then becomes incumbent on patients and their primary care physicians to be aware of their cancer history and their cancer treatment, and the potential consequences of that treatment."
"ASCO is working very hard to develop a template for a cancer-survivor care plan," Dr. Gralow noted. It will contain details of the cancer that the patient had, the treatment received, and the potential consequences. The patient will have this document and will be able to present it to any doctor who becomes involved in his or her care.
Risk is Increased, But Overall Risk is Low
The highest risk for cardiovascular disease was seen in survivors who had undergone treatment with either anthracyclines (doses above 250 mg/m2) or radiation to the heart area (doses above 3500 Gy). These individuals had a two- to five-fold increased risk for cardiovascular disease, compared with survivors who underwent other types of treatment.
Anthracyclines are already known for their cardiotoxic effects, Dr. Mulrooney commented; previous studies have shown a risk for dilated myopathy and congestive heart failure, and this seems to be progressive over time. The mechanism is thought to involve iron deposited in the heart, but more work needs to be done on this, he said. The damage from radiation seems to be inflicted on the pericardium and the epithelial lining of blood vessels, and the vessel disease seen in these young adult cancer survivors is different from what you would see in an older population with cardiovascular disease, he commented.
"Typically, in these older patients on a coronary angiogram, you would see diffuse disease and lipid deposits that have occurred over time; in cancer survivors who have received chest radiation, you typically see injury to the coronary artery and deposits that are very proximal to the heart. Why this is the case is not clear at the current time," he said.
Children in this study were treated between 1970 and 1986, and therapy has changed since then, Dr. Mulrooney commented. "We now have more targeted therapies and new...ways to give radiation therapy that give off less scatter, hopefully less scatter to the heart itself. And we have different ways of administering drugs, for example continuous infusions instead of bolus doses," he commented. "We don't know yet what the long-term results will be with these new modalities. But hopefully they will maintain the efficacy that we have seen while reducing the long-term adverse effects."
Dr. Mulrooney emphasized that although the risk for heart disease is significantly increased in survivors, the overall risk of developing cardiovascular problems is low. Thirty years after a diagnosis of childhood cancer, 2% of survivors had atherosclerosis, 4% had congestive heart failure, 1% had myocardial infarction, 3% developed pericardial disease, and 4% had valvular heart disease.
The researchers have disclosed no relevant financial relationships.
American Society of Clinical Oncology 2008 Annual Meeting: Abstract 9509. Preview presscast, May 15, 2008.
Medscape Medical News © 2008 Medscape
Cite this: Zosia Chustecka. Childhood Cancer Survivors at Increased Risk for Premature Heart Disease - Medscape - May 21, 2008.
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