Clusters of common pediatric cancers in Loire-Atlantique
Background and Timeline of Events
Between 2015 and 2019, several cases of pediatric cancer were reported in the area encompassing several municipalities: Sainte-Pazanne, St-Hilaire-de-Chaléons, St-Mars-de-Coutais, and Rouans. Following these reports, the Pays de la Loire Regional Health Agency referred the matter to Santé publique France.
An initial investigation was conducted in 2017 by health authorities, confirming an excess of leukemia diagnoses over a two-year period among children under 15, compared to expected cases. Analysis of environmental risk factors identified four potential leads that could not be ruled out and did not conclude that there was a common cause for the reported cases.
Following the reporting in February 2019 of three additional cancer cases (one child and two young adults), including one in the Sainte-Pazanne area (44), the Pays de la Loire Regional Health Agency (ARS) referred the matter to Santé publique France on March 28, 2019, to conduct investigations into the new reports.
At the same time, a collective was formed at the initiative of parents. It brings together 30 people living in the four municipalities affected by pediatric cancers.
Establishment of a monitoring committee and a technical committee
A monitoring committee was established in Nantes in May 2019 by the ARS Pays de la Loire in collaboration with Santé publique France, to share information on studies and actions carried out by various agencies. This committee brings together professionals from the ARS, Santé publique France, and other relevant decentralized state agencies (Prefecture, Regional Directorate for the Environment, Planning, and Housing (DREAL)), local elected officials, school representatives, healthcare professionals, representatives of the Collective, and a residents’ association. The ARS and Santé publique France facilitate opportunities for exchange and dialogue with civil society through this monitoring committee, as well as through public meetings. This committee is chaired by Professor Jacques Dubin, an oncologist, maxillofacial surgeon, and ENT specialist.
To respond to the referral and design its investigations, Santé publique France has established a technical committee bringing together all of the agency’s expertise. It also draws on experts from outside the agency, including the pediatric oncology department at Nantes University Hospital, the Loire-Atlantique and Vendée Tumor Registry, and the National Registry of Childhood Cancers (Inserm).
An update on the various investigations and studies launched by Santé publique France:
In 2019:
An epidemiological investigation to identify a possible common local source of exposure for these reported childhood cancers.
A local context survey to identify all the concerns and questions of the various stakeholders as well as the actions taken by these actors. The Pays de Loire Regional Health Agency (ARS) also conducted environmental investigations aimed at quickly “clearing up doubts” regarding certain exposures based on a set of specifications developed with Santé publique France. To this end, Santé publique France enlisted the assistance of experts outside the Agency to ensure that all potential hazards were considered in this effort to resolve doubts. The ARS, for its part, consulted with the IRSN regarding the issue of radon exposure.
In 2020:
At the request of stakeholders, Santé publique France, in collaboration with the Loire-Atlantique and Vendée registry, conducted:
a study of the geographic distribution of pediatric cancers in Loire-Atlantique between 2005 and 2018, comparing the situation in this selected area of seven municipalities with the rest of the department. The statistical analysis concluded that there was no abnormally high risk of pediatric cancers in the Sainte-Pazanne area compared to the rest of the department. Furthermore, a spatio-temporal scanning analysis did not reveal a significant and persistent clustering of childhood cancers in the department.
Additionally, the epidemiological study did not identify any common cause that could explain this cluster of pediatric cancers in this area.
In light of the conclusions of the various studies, Santé publique France has concluded the epidemiological investigation. Surveillance continues in the area in collaboration with the University Hospitals of Nantes and Angers and the registries to monitor the epidemiological situation over time. This surveillance relies on the comprehensive and early identification of any new child diagnosed with cancer within the investigation area.
Where do we stand today?
After two years of surveillance in the area, Santé publique France has published an epidemiological update, the results of which show that:
As of October 1, 2022, 19 children under the age of 18 were diagnosed in the area comprising the 7 municipalities (Machecoul-Saint-Même, Port-Saint-Père, Sainte-Pazanne, Rouans, Saint-Hilaire-de-Chaléons, Saint-Mars-de-Coutais, Villeneuve-en-Retz) between 2015 and September 2022. The date of diagnosis for the last reported case was July 2021;
The local situation is considered generally stable from an epidemiological standpoint compared to the findings of the 2019–2020 investigation;
The continuation of this enhanced surveillance, initially planned for three years, will be evaluated at the end of 2023.
Santé publique France continues to contribute to research: a non-exhaustive overview of ongoing work on the links between environmental factors and pediatric cancers in France is presented in the document, along with a summary of the current state of knowledge on risk factors for pediatric cancers (prepared by the National Registry of Pediatric Cancers).
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bulletin régional
16 November 2022
Suspected cluster of pediatric cancers in Loire-Atlantique. Update as of October 5, 2022.
Current understanding of risk factors for pediatric cancers and ongoing research (Source: Jacqueline Clavel and Brigitte Lacour of the INSERM Research Team on the Epidemiology of Cancers in Children and Adolescents - RNCE)
At present, no environmental exposure has been established as a risk factor for childhood cancers under “normal” conditions. Unlike adult cancers, very few carcinomas develop in children, and the many environmental risk factors established in adults—related to occupational settings and lifestyle habits—do not apply to children. Ionizing
radiation is a recognized risk factor in environmental disaster situations. It is thus responsible for thyroid cancers among Ukrainian and Belarusian residents affected by the Chernobyl accident, and for all types of cancers among survivors of the bombings of Hiroshima and Nagasaki. The Epstein-Barr virus is a proven risk factor for nasopharyngeal cancer, Hodgkin’s lymphoma, and Burkitt’s lymphoma. In the latter case, in the sub-Saharan environment conducive to Anopheles mosquitoes, malaria acts as a cofactor.
A great deal of data has been gathered on other environmental exposures, though no firm conclusions have been reached. The rarity and diversity of childhood cancers, the need for significant contrasts in exposure to detect differences in risk between exposed and unexposed children, the difficulty of tracing exposure history back to the intrauterine period, and the absence of persistent exposure markers at the time of cancer diagnosis complicate the search for risk factors and necessitate research at the national or international level. The past 30 years have been productive and have allowed for the documentation of several hypotheses:
The role of low-dose ionizing radiation from natural sources (radon and telluric gamma radiation) is highly debated. No excess risk of leukemia has been observed in France over 30 years of observation, but doubts persist in some countries. It is much more difficult to study the risk of brain tumors, and even more so for other solid tumors, because these are highly varied and heterogeneous tumors with small sample sizes. Nevertheless, while it remains difficult to rule out the possibility of any cancer risk linked to these environmental exposures, current data suggest that such a risk, if it exists, can only be very moderate;
Residential exposure to pesticides, particularly during pregnancy, has been associated with an increased risk of childhood leukemia and brain tumors in numerous studies. This increase, on the order of 50%, has not, however, been established with certainty, as the data rely largely on the recollections of parents of both sick and healthy children. Research into biological markers of exposure that persist over several years, or any other objective indicator of exposure, would help shed light on the role of these frequent exposures;
Exposure to traffic and air pollution has been studied to a somewhat lesser extent. Current data suggest an increased risk of leukemia among the most exposed children, which needs to be confirmed and clarified. Data are much more limited and heterogeneous regarding tumors of the central nervous system and are very insufficient regarding other types of cancer;
Exposure to extremely low-frequency magnetic fields generated by high-voltage power lines has been implicated following the observation of a higher risk of leukemia among children living in the immediate vicinity of very high-voltage power lines. Recent epidemiological data are much less supportive of this association, which, moreover, has no biological basis.
Lifestyle factors, while not strictly environmental in nature, have often been linked to the risk of childhood cancer. For example, paternal tobacco use prior to conception is thought to increase the risk of leukemia. Conversely, certain factors such as extended breastfeeding, maternal preconception folic acid supplementation, and—for leukemias—early childhood infections and daycare attendance may have a protective effect.
Many questions remain, and they are the subject of very active French research https://rnce.inserm.fr/, https://programme-pediac.com/ and international research https://www.clic.ngo/.
bulletin régional
9 December 2019
Incidence of pediatric cancers across several municipalities in Loire-Atlantique. As of November 29, 2019.
