Investigators track cancer treatments’ lasting impact
Can the high doses of chemotherapy and radiation that young cancer patients receive someday cause inherited health problems for their children?
Vanderbilt-Ingram Cancer Center's John Boice, Sc.D., and an international team of colleagues have been awarded a $4 million grant from the National Cancer Institute to investigate this issue.
Treating cancer in children has become increasingly successful, with approximately 270,000 childhood cancer survivors living in the United States today.
“Thirty years ago, the focus was just on survival; we were just treating the disease,” said Boice. “Now because many more children and young adults are surviving, we're in a different mode. We're also very concerned about quality of life,” he added.
Boice said because children and young adults who were treated for cancer are living longer, researchers have new questions to try to answer, such as: why some curative therapies may cause infertility, yet many cancer survivors are able to have children of their own; and why most babies born to cancer survivors suffer no inherited health problems, but some have birth defects, die prematurely, or are stillborn — as is the case for some babies born to parents who never had cancer.
Boice is trying to determine what the level of risk might be for a cancer survivor who is able to have children. So far, he said it looks like the risk is not as high as might be expected.
“Our initial data indicate that the level of adverse genetic effects among children of cancer survivors is not remarkably different than seen in the general population. If it were, we already would be able to see larger numbers of offspring being born with birth defects or dying early,” said Boice. “This suggests that the human genome may not be as susceptible for inherited effects as other species, despite high exposures to radiation and chemotherapy.”
Boice and colleagues will try to quantify the risks of birth defects and other adverse outcomes for offspring of cancer survivors based on the amount of chemotherapy and radiation received. “We're also taking blood samples from the survivor, their spouse and their children to look at the molecular level for markers for genetic effects.”
Boice is working closely with researchers in Denmark and Finland, where all persons diagnosed with cancer under the age of 35 after 1943 in Denmark, and 1952 in Finland, have been identified using extensive databases containing a wealth of patient information. Boice said because no comparable system exists in the United States, collecting data here is more problematic.
“Adverse outcomes are rare, so we have to be able to study large groups of cancer survivors in order to develop precise estimates of risk,” Boice said. Already, over 59,000 cancer survivors who had 19,000 children have been identified in Denmark and Finland.
Over the next five years, the study team will continue to identify survivors and their children, as well as siblings of cancer survivors.
“We will determine whether the children of cancer survivors have more adverse conditions than the children of siblings of people with cancer,” he said. “Because many more people are surviving cancer now than in years past, we'd like to be able to tell them what, if any, risks their cancer treatment has had on their children,” said Boice.
Boice, in the Center for Epidemiology of the Department of Medicine, is collaborating with scientists in several Vanderbilt departments, including Bertrand Brill, M.D., Ph.D., research professor of Radiology and Radiological Sciences, James Whitlock, M.D., director of Pediatric Oncology, as well as many others. The Danish Cancer Society, Finnish Cancer Registry, International Epidemiology Institute, University of Texas MD Anderson Cancer Center, and Westlakes Research Institute (in the U.K.) are also part of the extensive research project.