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Poor air quality linked to hospitalizations among childhood cancer survivors
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Poor air quality days significantly increased the risk for respiratory-related hospitalizations among childhood cancer survivors, according to results of a study conducted by researchers at Huntsman Cancer Institute at University of Utah.
“This study has wide application to cancer survivors in Utah as well as nationwide,” Judy Ou, PhD, cancer epidemiologist at Huntsman Cancer Institute, said in a press release. “There are approximately 17 million cancer survivors in the United States, and statistics show about 40% of this population lives in places that are considered polluted at certain times of the year.”
Investigators examined the medical records of approximately 4,000 childhood, adolescent and young adult cancer survivors diagnosed or treated between 1986 and 2012. They identified all ED visits and hospitalizations in Utah due to respiratory illness.
Results showed the risk for respiratory hospitalization was significantly increased among survivors who received chemotherapy.
“We really have not thought about how environmental exposures may affect long-term health care needs and health outcomes. We may need to rethink guidelines, both on air pollution notifications from public health agencies as well as guidelines we are giving [patients with cancer],” Anne Kirchhoff, PhD, associate professor of pediatrics at University of Utah, said in the release.
HemOnc Today spoke with Kirchhoff and Ou about the study, the clinical implications of the findings, and what subsequent research will entail.
Question: What prompted this research?
Kirchhoff: We were interested in conducting this study because we have unique data resources, including the Utah Population Database and Utah Cancer Registry, that allow us to assess patients with cancer and survivors at a state level and to tie their residency history to air pollution.
Ou : Pulmonary complications are among the many posttreatment problems childhood cancer survivors often face. Previous research has shown how clinical treatments affect the risk for lung problems long after treatment ends, but there has been no research on the environment in which survivors live and how pollution could affect their lung health. We are the first to look at how environmental pollutants affect this population of patients’ lung health through examining their ED use and hospitalizations.
Q: How did you conduct the study?
Ou : Using the Utah Population Database, we identified survivors diagnosed with cancer from birth to age 25 years treated at the largest pediatric cancer hospital in Utah. We then identified when they started treatment and followed them 5 years after treatment. We examined every ED visit and hospitalization that could have been caused by air pollution. Events included difficulty breathing, asthma and other respiratory complications that have been biologically linked to air pollution exposure. This study is a case-crossover study, in which we compared pollution levels that cancer survivors experienced within 3 days before a hospitalization or an ED visit with levels on days within the same month when they did not have a visit. The aim was to see why this event happened on that specific day. We also looked at how air pollution influenced risk for similar events among population controls — people who were the same age as cancer survivors but had been cancer free up until that time point.
Q: What did you find?
Kirchhoff: Most of our significant findings were in hospitalizations rather than ED visits. Unfortunately, we are seeing a higher risk for things that require patients to receive intense care in the hospital.
Ou : Pollution levels 3 days before a hospitalization or ED visit were higher than on days when no events occurred. This allowed us to quantify the risk for having one of those events from exposure to air pollution. We found air pollution alone is associated with increased risk for hospitalizations and certain ED visits among childhood cancer survivors. Also, risk among survivors was higher than among the general population, especially among survivors treated with chemotherapy — their risk was significantly higher. Additionally, respiratory infections were the most prevalent outcomes that we saw as a result of air pollution exposure.
Q: What are the clinical implications of the findings?
Kirchhoff: There are not only clinical implications, but also public health implications. For example, guidelines state that on days where air pollution is high, certain individuals such as those with asthma should avoid prolonged outdoor activity. Others who may be vulnerable, such as cancer survivors, have not been considered in these guidelines. Therefore, as we build on this research, we hope to be able to provide better guidance for patients with cancer and survivors about potentially avoiding days of high air pollution.
Ou : We have opened a new area of research because not many people in the clinical world have thought about the effects of environments in which cancer survivors live. Clinical guidelines published by Children’s Oncology Group include suggestions for patients to follow once treatment is over, such as visiting a doctor regularly, maintaining a healthy diet, exercising and avoiding smoking. However, none of these guidelines recommends caution with environmental pollution. Perhaps we should start thinking about environmental exposures among cancer survivors in the same way that clinicians think about smoking after treatment for cancer is over.
Q: What will subsequent research on this entail?
Ou: We have submitted grants to advance the population we examined. For the current study, we looked at those diagnosed at age 25 years and younger, but we would like to expand this to all pediatric, adolescent and young adult survivors up to age 39 years at cancer diagnosis. We also are interested in examining specific cancer sites, because we know that breast cancer survivors have a lot of cardiac and respiratory issues linked to chemotherapy. We would like to look at other populations, as well, such as testicular cancer survivors, and we are interviewing parents of children who had cancer to try to get an idea of their perceptions of late effects and how the environment can influence the health of their child who survived cancer.
Q: Is there anything else that you would like to mention?
Kirchhoff: We conducted our study here in Utah, but we believe the results can have implications for survivors across the United States. We hope to build upon this research and look at patient groups in other areas, as well.
Ou : Because of advances in detection and treatment, the number of cancer survivors in the U.S. is growing rapidly, and a lot of these survivors are going to have continued problems related to their treatment. Providing them with answers related only to their treatment might not be sufficient to help them as they cope with that survivorship and understand their individual risks. We are trying to help cancer survivors feel empowered in taking control of their health after treatment and provide them with guidance to help navigate that difficult post-treatment time period. – by Jennifer Southall
Reference:
Ou JY, et al. Int J Environ Res Public Health. 2019;doi:10.3390/ijerph16061081.
For more information:
Anne Kirchhoff, PhD, can be reached at Huntsman Cancer Institute at University of Utah, 2000 Circle of Hope Drive, Salt Lake City, UT 84112; email: anne.kirchhoff@hci.utah.edu.
Judy Ou, PhD, can be reached at Huntsman Cancer Institute at University of Utah, 2000 Circle of Hope Drive, Salt Lake City, UT 84112; email: judy.ou@hci.utah.edu.
Disclosures: Kirchhoff and Ou report no relevant financial disclosures.