Urban environment and cancer in wildlife: available evidence and future research avenues

Abstract

While it is generally known that the risk of several cancers in humans is higher in urban areas compared with rural areas, cancer is often deemed a problem of human societies with modern lifestyles. At the same time, more and more wild animals are affected by urbanization processes and are faced with the need to adapt or acclimate to urban conditions. These include, among other things, increased exposure to an assortment of pollutants (e.g. chemicals, light and noise), novel types of food and new infections. According to the abundant literature available for humans, all of these factors are associated with an increased probability of developing cancerous neoplasias; however, the link between the urban environment and cancer in wildlife has not been discussed in the scientific literature. Here, we describe the available evidence linking environmental changes resulting from urbanization to cancer-related physiological changes in wild animals. We identify the knowledge gaps in this field and suggest future research avenues, with the ultimate aim of understanding how our modern lifestyle affects cancer prevalence in urbanizing wild populations. In addition, we consider the possibilities of using urban wild animal populations as models to study the association between environmental factors and cancer epidemics in humans, as well as to understand the evolution of cancer and defence mechanisms against it.

Ecological and Evolutionary Consequences of Anticancer Adaptations

“…Relationships between environmental contaminants and tumor development in wildlife remain only partially understood at the moment, both because neoplasia detection in wild animals is often complex and also because several parameters intervene in the way pollution influences the development of oncogenic processes (ecological status, life history characteristics, variation in cancer defense mechanisms and/or tolerance, and also the combined effects of pollutants; see Sepp et al., 2019 , Giraudeau et al., 2018 ). However, it remains, for instance, clearly established that effluents from aluminum smelting facilities are responsible for intestinal adenocarcinoma in beluga whales ( Delphinapterus leucas ) in the Saint Lawrence Estuary ( Martineau et al., 1994 ) ( Martel et al., 1986 ).…”

Predation shapes the impact of cancer on population dynamics and the evolution of cancer resistance

“…For example, cancer prevalence ranges from 1% to 30% among fishes, and up to 25% in birds and mammals (Madsen et al, 2017). Furthermore, cancer prevalence in wildlife is also exacerbated by anthropic activities (Giraudeau, Sepp, Ujvari, Ewald, & Thomas, 2018; Sepp, Ujvari, Ewald, Thomas, & Giraudeau, 2019).…”

The deteriorating soma and the indispensable germline: gamete senescence and offspring fitness

“…However, unrepaired mutations, while rare, do occur and can increase with parental age in both sexes [52,[65][66][67]. Robust estimates of germline mutation rates are still limited, but overall they appear to occur at a higher rate in humans and other primates than in the other vertebrate and invertebrate taxa that have been studied [68][69][70][71]. Most detailed information comes from studies of humans and mice.…”