Host Dr. Davide Soldato and his guests Dr. Ann Wu and Dr. Alexa White discuss the article " Air Pollution and Breast Cancer Incidence in the Multiethnic Cohort Study " and the editorial " Growing Evidence for the Role of Air Pollution in Breast Cancer Development " TRANSCRIPT The guests on this podcast episode have no disclosures to declare. Dr. Davide Soldato: Hello and welcome to JCO After Hours , the podcast where we sit down with authors from some of the latest articles published in the Journal of Clinical Oncology . I am your host, Dr. Davide Soldato , Medical Oncologist at Ospedale San Martino in Genoa, Italy. Today, we are joined by JCO authors Dr. Anna Wu and Dr. Alexander White. Dr. Wu is a professor of Population and Public Health Sciences at the Keck School of Medicine of UCS, while Dr. White is an investigator in the Epidemiology branch of the Environment and Cancer Epidemiology Group at the National Institute of Health. Today, we will be discussing the article titled, " Air Pollution and Breast Cancer Incidence in the Multiethnic Cohort Study ," and the accompanying editorial . So, thank you for speaking with us, Dr. Wu, Dr. White. Dr. Anna Wu: Thank you for having us. Dr. Alexandra White: Yes, thank you so much for the invitation to be here. Dr. Davide Soldato: So before going in depth about the results of the study that was published in the JCO , I was wondering if you could give us like a brief introduction and a little bit of background about what was known about air pollution as a risk factor for breast cancer and what was the evidence before this study was conducted. Dr. Alexandra White: Okay. I can start with that question. So, there's been research for decades looking at the relationship between air pollution and breast cancer. And it's been a really challenging question to address for a number of reasons. One being that it can be really difficult to assess exposure to air pollution and many previous studies have had really limited information on people's residences over time. But in general, what we thought leading up to this study was that evidence was most consistent that exposure to traffic related pollutants such as nitrogen dioxide was more consistently related to a higher risk of breast cancer. The evidence for fine particulate matter or PM2.5 was less consistent. More recently, there have been a few large, well conducted studies that have supported a positive association. This new study in the multiethnic cohort led by Dr. Wu is really important because it really demonstrated that, in this large study of over 50,000 women in California, that they also do see an association with PM2.5. Dr. Davide Soldato: Thank you very much for the introduction. So, Dr. Wu, we just want to hear a little bit more about the results. So, what was the association that was observed for PM2.5? And specifically, the study that you ran was focused on a very diverse population, a multiethnic cohort, and so I was wondering if you observed any type of differences when you consider the different populations that were included in your study. And if you could also give us a little bit of what was the composition of the women that were enrolled in this cohort. Dr. Anna Wu: Thank you for the question. So, the multiethnic cohort study is a cohort of over 200,000 individuals who were enrolled when they lived in Hawaii or California. For the air pollution studies that we've been conducting, we have focused on primarily the California participants. And in this instance for the breast cancer study, it was based on roughly 56,000 individuals out of- there were about 100,000 because half of them were men and they were not included. Of the California participants, 75% of them were African Americans or Latinos and they were self-identified as these racial ethnic groups when they enrolled in the study. And this was a particularly important consideration for us because in most of the studies that have been published so far on-air pollution and breast cancer, as well as other cancer sites, most of those studies were conducted among whites in the US or whites in Europe. And even if they included non-white populations, the numbers tend to be small so that they were not able to conduct racial ethnic specific analysis. So, we were particularly interested in examining these other racial ethnic groups because we know from other studies that racial ethnic minority groups tend to live in communities of low socioeconomic status and those communities also tend to have higher levels of various types of environmental pollutants. And so, it was important for us to actually try to tease apart these various interrelated factors. So, what we found was that per 10 micrograms per cubic meter, we had a 28% increased risk overall in all participants combined that meet across the racial ethnic groups. We actually did not see any differences or significant differences in the hazard ratios by race ethnicity and they were in general quite compati
