THE ESSENTIAL
- Researchers show an association between exposure to PM2.5 and the incidence of head and neck cancer.
- “These results highlight the important role of environmental pollution in cancers of the upper aerodigestive tract, highlighting the need for continued awareness, research and mitigation efforts,” indicates the lead author of the work.
- The researchers wish to expand their work, in particular because the effects of carcinogenesis induced by certain viruses could not be taken into account “due to the limited availability of data”.
“Research has already been done on air pollution, but the effects were mainly linked to lower respiratory cancers”, points out John Cramer, associate professor of otolaryngology at Wayne State University School of Medicine and one of the authors of the new publication titled “Exposure to air pollution and incidence of head and neck cancer”. Indeed, we can for example cite this study published last year in the journal Naturewhich shows that air pollution, and in particular fine PM2.5 particles, increases the risk of lung cancer in non-smokers. “For head and neck cancer, much less common than lung cancer, the link is more difficult to establish. But since it is also linked to smoking, like lung cancer, we wanted to explore possible links [avec la pollution de l’air, ndlr]. [En effet, ndlr] Presumably the link to head and neck cancer comes from what we breathe and this substance that affects the lining of the head and neck. We see many cases where carcinogens come into contact or accumulate in the body and cancers can occur.”
The effects of PM2.5 on cancer risks are more pronounced 5 years after exposure
To carry out this work, the results of which were published in the journal Scientific Reportsthe researchers relied on the US National Surveillance Epidemiology and End Results (SEER) cancer database for the years 2002-2012. They focused on people’s exposure to fine PM2.5 particles; that is to say very small particles, measuring less than 2.5 microns. “Particle size is important because the classic model for studying the upper respiratory tract is that the nose and throat act as filters before particles enter the lungs. Larger particles are filtered out, but we conceptualize that different types of pollution hit different parts of the airways”, specifies the scientist.
The scientists thus observed the strongest association between exposure to PM2.5 and the incidence of head and neck cancer after a latency period of five years.
Head and neck cancer: we must take into account “the important role of environmental pollution”
“These findings highlight the important role of environmental pollution in upper aerodigestive tract cancers, underscoring the need for continued awareness, research and mitigation efforts.” says lead author Dr. Stella Lee of the Center for Surgery and Public Health and the Division of Otolaryngology-Head and Neck Surgery at Brigham and Women’s Hospital.
Moving forward, the researchers would like to expand their work by taking into account other data sets. Indeed, this study was limited to the effects of PM2.5, while other components of atmospheric pollution, such as nitrogen dioxide (NO2), PM10 or even ozone, have shown that they had an impact on the incidence of other malignancies, particularly lung cancer. Furthermore, this study presents another major limitation: the data linked to the effects of carcinogenesis induced by certain viruses, in particular human papillomavirus (HPV) in the oropharynx and Epstein-Barr virus (EBV) in the nasopharynx, were not taken into account “due to limited data availability”, as well as other data related to smoking or alcoholism. “However, the large representative sample size of the SEER database makes these results more reliable despite population variability”, add the authors.
