Ep. 85: Environmental Factors and Childhood Cancer

There is a growing body of literature that has implicated the role of several environmental hazards in childhood cancer, such as exposure to pesticides, vehicle exhaust, gasoline, and tobacco smoke, all of which can increase the risk of a childhood cancer diagnosis. A new training program developed by the Western States Pediatric Environmental Health Speciality Unit at the University of California San Francisco (UCSF) aims to support and educate physicians so they, in turn, can offer practical guidance to parents and caregivers on how to prevent exposure to toxic chemicals associated with childhood cancer risk. The program is funded and supported by the Agency for Toxic Substances Disease Registry, part of the CDC  and the American Academy of Pediatrics.

GUESTS:
Dr. Mark Miller, Director Emeritus of the Western States Pediatric Environmental Health Specialty Unit at the University of California, San Francisco (UCSF)

Dr. Catherine Metayer, Director of the Center for Integrative Research on Childhood Leukemia and the Environment at the University of California Berkeley School of Public Health

Dr. Joe Wiemels, PhD,  Professor of Population and Public Health Sciences and director of the PhD Epidemiology program, University of Southern California

This project is sponsored by the Pediatric Environmental Health Specialty Units. For more information, go to PEHSU.net.

Carol Vassar, producer

Views expressed by guests do not necessarily reflect the views of the host or management.

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Transcript

Carol Vassar, podcast host/producer:

Welcome to Well Beyond Medicine, The Nemours Children's Health Podcast. Each week, we'll explore anything and everything related to the 80% of child health impacts that occur outside the doctor's office. I'm your host, Carol Vassar. And now that you are here, let's go.

Music:

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Carol Vassar, podcast host/producer:

Sometimes, physicians need to deliver unimaginably heartbreaking news to patients and their families. Imagine, if you will, having to explain to a family that their child has cancer. Within the shock of the news come questions, some of which can be answered and others can't. Perhaps the most obvious question is one of the most difficult to answer, "Why and how did this happen to my child?" While there is no single answer to that question, and there are still many unknowns in the world of cancer, there is a growing body of literature that has implicated the role of several environmental hazards in childhood cancer, such as exposure to pesticides, vehicle exhaust, gasoline, and tobacco smoke, all of which can increase the risk of a childhood cancer diagnosis.

So when questioning parents turn their attention to environmental factors, especially in the home, how can physicians prepare themselves to respond? A new training program developed by the Western States Pediatric Environmental Health Specialty Unit at the University of California San Francisco, UCSF, aims to support and educate physicians to respond to those tough queries by offering practical guidance on preventing exposures to toxic chemicals associated with childhood cancer risk. The program is funded and supported by the Agency for Toxic Substances Disease Registry, part of the CDC, and the American Academy of Pediatrics.

Here to share more about both the current body of research in this area and the Childhood Cancer and the Environment physician training program are Dr. Mark Miller, Director Emeritus of the Western States Pediatric Environmental Health Specialty Unit at UCSF, epidemiologist Dr. Catherine Metayer, Director of the Center for Integrative Research on Childhood Leukemia and the Environment at the University of California Berkeley School of Public Health, and researcher Dr. Joe Wiemels, PhD,  Professor of Population and Public Health Sciences and director of the PhD Epidemiology program, University of Southern California. Dr. Miller gets us started by filling us in on some of the research that led to the development of this new physician training program.

Dr. Mark Miller, University of California San Francisco:

Over the last 20 years, the Childhood Leukemia International Consortium, so the international body and the Center for Integrative Research on Childhood Leukemia and the Environment have produced a large body of research, along with their collaborators and other researchers around the world, about the environmental risk factors for childhood leukemia and other childhood cancers. So things that rise to the top include air pollution, particularly related to traffic, volatile organic compounds known as DOCs, exposure to tobacco, including pre and periconception paternal use of tobacco, as well as childhood exposure to secondhand smoke and pesticides. So Catherine Metayer has done a lot of that research and could tell us a little bit more about that.

Dr. Catherine Metayer, University of California Berkeley:

Sure. We've been studying the impact of exposure to pesticides on the risk of childhood leukemia, and most of us are exposed to pesticides through many different sources. You can use pesticide at home, you can be living close to an area where pesticide is being applied. Your parents could be actually working in the field and be farmers and be exposed to pesticides. So, all those different sources have potential impact on the child. And our study and studies around the world have looked at this very different angle, and what we find out is that the father who is reporting using pesticide at work has a higher risk to have a child with leukemia. If the family is using pesticides at home, the risk is increased on average by maybe 30%.

We also went to the homes of the families who participated in our study in California and measured different chemicals in the dust. The dust being this mixture of different chemicals that accumulates over time, over and over. And that's a very interesting source for us to understand daily exposure to many chemicals. And here, we found that exposure to specific herbicides was increasing the risk of childhood leukemia. So I would say that overall, from all work in California, but work done in other groups in the US and in Europe, there is a high level of evidence that exposure to pesticides in some fashion will have an impact on childhood leukemia risk.

Carol Vassar, podcast host/producer:

It sounds like it's a worldwide issue.

Dr. Catherine Metayer, University of California Berkeley:

Exactly. As a matter of fact, it was fairly easy to work with the Childhood International Leukemia Consortium because they're asking the same questions. Whether you are in Italy, in France, in Greece, in the US, in Canada, those exposures are ubiquitous. They're all over the place. There's no escaping being exposed to pesticides. So yes, indeed, that has been an interest from many, many different groups, which has helped to bring strong evidence between the link between leukemia and pesticide exposure.

Carol Vassar, podcast host/producer:

Joe, I want to ask you this question. In 2022, this team and many others, I'm sure, initiated an education and training program called Childhood Cancer and the Environment. Who was the audience for this particular project?

Dr. Joseph Wiemels, University of California San Francisco: 

The audience were primary caregivers. So we were trying to target medical fellows who are just starting to get into clinical care and nurse practitioners so that they would learn the importance of the environment and have tools that they could go back and speak with their communities, their patients, and their patient families. We found that they gave us information that they didn't feel like they had the adequate tools, the knowledge to consult with families who had asked them questions, "Why did my child get cancer?" And it's not that they want to tell those families, "Oh, you didn't clean your home properly," or something like that. They wanted to be able to explain childhood cancer is a very rare outcome. The whole of society is exposed to these important factors that we're talking about. So there is some element of bad luck perhaps, but it's not only that there are differences in the ways that we metabolize chemicals, there are differences in the ways that we respond, and those mutations occur and when they happened in the child's life, that may have impacted one child more than others.

So, there are changes we can make to reduce toxic pollutants in a society as a whole that will have profound impact on those children who have risk to cancer. And really, what we're trying to do is understand what is the combination of what that child was born with and interacted with, at what points in their life they are most susceptible to having those genetic and epigenetic changes that lead to cancer and then prevent it at those times in those children's lives and to get that information back to the families.

Carol Vassar, podcast host/producer:

So we've had a great overview of what was missing, but I'm wondering what the knowledge gaps were amongst these nurse practitioners, amongst pediatricians and maybe even amongst caregivers, parents, and the general public with regard to this.

Dr. Mark Miller, University of California San Francisco:

We've done a lot of work specifically with care providers, physicians, fellows, nurse practitioners, and some social workers that take care of children with cancer. And we did a survey back in 2015 of about 200 of these care providers, and half of them said that they didn't ask any questions really about these factors and they were uncomfortable answering parents' questions about this. So that goes with what we hear is commonly said or is even on the American Cancer Society or the National Cancer Institute's website, that other than a small percentage of childhood cancers related to genetic syndromes, that we don't know the cause of childhood cancers. They're mostly not familiar with the literature on this. The literature on childhood cancer in the environment is generally published in the journals that the care providers don't read. So they're in environmental health perspectives or similar environmental or epidemiologic journals.

The past year, we focused primarily on pediatric oncology providers, and they're at a loss. They're uncomfortable answering these questions that they're commonly asked and they feel like they don't have the information that they had. They didn't learn about this in medical school, in pediatric residency, or in their fellowship training. So there's a lack of basic knowledge about these key sources of information, factors that impact both the causation of disease, but also now we're beginning to develop information that identifies that their factors also that can affect the outcomes of these diseases.

Carol Vassar, podcast host/producer:

So, Catherine, tell me about this pilot project that you did.

Dr. Catherine Metayer, University of California Berkeley:

So, I'm an epidemiologist, and I'm doing those great studies that are published, as you mentioned, in those journals, but then the data are just staying there and not being taken outside of our box, outside to different audiences, and they can act on it. So, actually, our work with Mark studied 10 plus years ago to try to really bring the science outside of the university in a sense. But I think what we realized early on is that physicians can be our advocates. Patient and family do trust their physicians. So when they ask the question, "Why my child?" and the physician doesn't have an answer or dismiss the question, this is where you have your big gap because the families are in need to understand for their child possibly what could have happened wrong. So it's been a very, very tedious effort to reach out to physicians who are really focusing on the treatment, and we understand that they do not have the bandwidth to possibly go back and speak to the family.

So it takes an active effort to do that. And this is where Mark's group and ideas are coming in place, reaching out directly the physician in small groups because this is where you can really get the conversation going. We have those two-day seminars with clinicians in the room. You have dinner with them, you have breakfast with them, you create a relationship, and then people start talking, and then you can tell a bit more than what you told on the slide. So, really, it's a very novel model for me in terms of research translation. It's more personal because we found that the big venues and the big meetings will not get the message through, so you have to cultivate more deeply the relationship. So that's why this model of research translation, working directly with the physician, I think it's completely novel.

Carol Vassar, podcast host/producer:

As people come, doctors, social workers, physicians, to these seminars, are they taking this information back?

Dr. Mark Miller, University of California San Francisco:

Yeah, and we have information not only just following the meetings but three months later, and we get very positive reviews. Not only when we ask questions about specific items, did they learn? Did they feel more efficacious in their knowledge? But they also three months later, have put into action and changed both the way they answer parents' questions and, what they do with their colleagues, how they think about childhood cancer in the environment. One said, "I was completely ignorant before."

Dr. Joseph Wiemels, University of California San Francisco: 

One advantage of the long format of the workshop was that we were able to not only give sound bites about what chemicals were associated with this and that, the same information we get in a newspaper article, but we were able to bring the participants through right from conception to a child getting cancer years later and really be able to explain what points in life were important, what was going on in the child's health. And I think that that complete picture of the cancer process was something that closed a lot of the questions that participants would've had by just getting a short format. This is exposed to that, like we do.

Carol Vassar, podcast host/producer:

Is it scalable? Are you working to scale it?

Dr. Mark Miller, University of California San Francisco:

Yes, we're working to scale up. We have limited abilities still to do that, but this year, we built on the activities of last year by identifying an institution that was interested in developing a childhood cancer in the environment consultative service within their pediatric oncology program. So this is now a team that's just starting. We spent a full day and a half doing a educational program there, and they're now embarking on setting up a consultative service so that when questions come up or sometimes proactively, there are people that are knowledgeable and able to help families with information. So that includes both answering their questions but also potentially providing them with guidance so far as how to reduce exposures to air pollution or other chemicals that might, in fact, impact a subsequent child.

Dr. Catherine Metayer, University of California Berkeley:

So we are actually developing short videos that have a very specific focus on the biology of childhood leukemia, air pollution, on pesticides, on diet. So they're very precise presentations, which I think will really be very nice addition to those longer format where we need for couple of days, but can also be available to a physician that we know doesn't have much time. We know there's always this tension between my time, how much effort I want to put into new knowledge. Those videos can be available to them for short presentation, but just to give them a introduction to the world of the environment and childhood leukemia and childhood cancer risk.

Carol Vassar, podcast host/producer:

So there's certainly more to come. Anything else that you'd like to add? Dr. Miller?

Dr. Mark Miller, University of California San Francisco:

Yeah. Besides risk factors that have been identified, there are factors that reduce risk as well. So, for example, having adequate folate in the periconception and during the pregnancy periods reduces the risk of childhood leukemia. Being in a daycare center as an infant and young child that's got six or greater children in it reduces the risk of childhood leukemia.

Dr. Catherine Metayer, University of California Berkeley:

If I may add too, an important observation of those increasing trends, at least in the United States, is that mostly children of Latino background farther want to experience the highest risk and the strongest increasing trend. So the translation of our findings is also targeted to this population. They are at the most risk, and therefore there are at the most needs to be aware of what can be presentable. So this is very important that we work with this population to serve them the best.

Dr. Mark Miller, University of California San Francisco:

Factors associated with increased risk or, on the other side, decreased risk of childhood cancer are all things that are already identified as hazards for childhood exposure, air pollution, tobacco exposure. On the other side, adequate folate or folic acid during pregnancy. We know, for example on that for one, that it's important to reduce the incidence of neural tube defects, and for that reason, we fortify grains with it, but there's still 15-18% of women of childbearing age that have less than optimal folate levels, and so there's room to move forward. Part of our message is that these are things we're already working on, air pollution and pesticide exposures, so introducing that for the general pediatric provider, a message along with, while you're telling your patients to avoid pesticide exposure when possible or reduce that exposure, you may also reduce the risk of childhood cancer. That's a powerful message.

Dr. Joseph Wiemels, University of California San Francisco: 

One thing we know from population studies where we look at families in the population is that when a child gets cancer, the siblings of that child have between a two and a fivefold higher risk of getting cancer themselves simply because of shared genetics in the family, but also because of shared environment in the family. So even though a parent comes in with a child and has a little bit of angst about, "Did I cause this cancer because of some environment in my home, and do I really want to find out about that?" Well, mitigating that environment in the future is going to help that whole family. The other families are at a higher risk, and that gives them an opportunity to do something positive for their family and also to help that child who does have cancer reduce their environmental impact that would lead to other health effects as they're recovering from cancer

Carol Vassar, podcast host/producer:

Researcher Dr. Joe Wiemels is a Professor of Population and Public Health Sciences and director of the PhD Epidemiology program at the University of Southern California. He was joined in conversation by epidemiologist Dr. Catherine Metayer, Director of the Center for Integrative Research on Childhood Leukemia and the Environment at the University of California Berkeley School of Public Health, as well as Dr. Mark Miller, Director Emeritus of the Western States Pediatric Environmental Health Specialty Unit at UCSF.

Music: 

Well Beyond Medicine

Carol Vassar, podcast host/producer:

It should be noted that childhood cancer, while rare, will still affect nearly 10,000 children under the age of 15 in the US this year, according to the American Cancer Society. We extend our thanks to Doctors Miller, Metayer, and Wiemels for joining us today. And thanks to you for listening. It's a wide world of factors that happen outside the doctor's office and affect the health of children. What factors do you think we should be talking about here on the podcast? Leave us a voicemail on our podcast website, nemourswellebyond.org. There, you'll also find all of our previous podcast episodes, and you'll have an opportunity to leave a review of the podcast and to subscribe to it. That's nemourswellbeyond.org. The extraordinary production team on this episode includes Che Parker, Cheryl Munn, Susan Masucci, Lauren Teta, and Joe Gillespie, and we thank each and every one of them. I'm Carol Vassar, until next time, remember, we can change children's health for good well beyond medicine.

Music:
Well Beyond Medicine