Sea Turtles in the Cancer Risk Landscape: A Global Meta-Analysis of Fibropapillomatosis Prevalence and Associated Risk Factors

Authors: Antoine M. Dujon, Gail Schofield, Roberto M. Venegas, Frédéric Thomas and Beata Ujvari

Source: Pathogens (OCT2021)


Several cancer risk factors (exposure to ultraviolet-B, pollution, toxins and pathogens) have been identified for wildlife, to form a “cancer risk landscape.” However, information remains limited on how the spatiotemporal variability of these factors impacts the prevalence of cancer in wildlife.

Here, we evaluated the cancer risk landscape at 49 foraging sites of the globally distributed green turtle (Chelonia mydas), a species affected by fibropapillomatosis, by integrating data from a global meta-analysis of 31 publications (1994–2019).

Evaluated risk factors included ultraviolet light exposure, eutrophication, toxic phytoplanktonic blooms, sea surface temperature, and the presence of mechanical vectors (parasites and symbiotic species).

Prevalence was highest in areas where nutrient concentrations facilitated the emergence of toxic phytoplankton blooms. In contrast, ultraviolet light exposure and the presence of parasitic and/or symbiotic species did not appear to impact disease prevalence.

Our results indicate that, to counter outbreaks of fibropapillomatosis, management actions that reduce eutrophication in foraging areas should be implemented.

On the need for integrating cancer into the One Health perspective

Authors: Antoine M. Dujon, Joel S. Brown, Delphine Destoumieux-Garzón, Marion Vittecoq, Rodrigo Hamede, Aurélie Tasiemski, Justine Boutry ,Sophie Tissot, Catherine Alix-Panabieres, Pascal Pujol, François Renaud, Frédéric Simard ,Benjamin Roche, Beata Ujvari, Frédéric Thomas



Recent pandemics have highlighted the urgency to connect disciplines studying animal, human, and environment health, that is, the “One Health” concept. The One Health approach takes a holistic view of health, but it has largely focused on zoonotic diseases while not addressing oncogenic processes.

We argue that cancers should be an additional key focus in the One Health approach based on three factors that add to the well-documented impact of humans on the natural environment and its implications on cancer emergence.

First, human activities are oncogenic to other animals, exacerbating the dynamics of oncogenesis, causing immunosuppressive disorders in wildlife with effects on host–pathogen interactions, and eventually facilitating pathogen spillovers.

Second, the emergence of transmissible cancers in animal species (including humans) has the potential to accelerate biodiversity loss across ecosystems and to become pandemic. It is crucial to understand why, how, and when transmissible cancers emerge and spread.

Third, translating knowledge of tumor suppressor mechanisms found across the Animal Kingdom to human health offers novel insights into cancer prevention and treatment strategies.

Machine learning is a powerful tool to study the effect of cancer on species and ecosystems

Authors: Antoine M. Dujon, Marion Vittecoq, Georgina Bramwell, Frédéric Thomas, Beata Ujvari



Cancer is an understudied but important process in wildlife. Cancerous cells are proposed to have had significant effect on the evolution of metazoan species due to their negative effect on host fitness. However, gaining knowledge on the impact of cancer on species and ecosystems is currently relatively slow as it requires expertise in both ecology and oncology. The field can greatly benefit from automation to reduce the need of excessive manpower and analyse complex ecological datasets.

In this commentary, we examine how machine learning has been used to gain knowledge on oncogenic processes in wildlife. Using a landscape ecology approach, we explore spatial scales ranging from the size of a molecule up to whole ecosystems and detail, for each level, how machine learning has been used, or could contribute to obtain insights on cancer in wildlife populations and ecosystems.

We illustrate how machine learning is a powerful toolbox to conduct studies at the interface of ecology and oncology. We provide guidance for the readers of both fields on how to implement machine learning tools in their research and identify directions to move the field forward using this promising technology. We demonstrate how applying machine learning to complex ecological datasets will (a) contribute to quantitating the effect of cancer at different life stages in wildlife; (b) allow the mining of long-term datasets to understand the spatiotemporal variability of cancer risk factors and (c) contribute to mitigating cancer risk factors and the conservation of endangered species.

With this study, we aim to facilitate the use of machine learning to wildlife species and to encourage discussion between the scientists of the fields of oncology and ecology. We highlight the importance of international and pluridisciplinary collaborations to collect high-quality datasets on which efficient machine learning algorithms can be trained.

Tumors (re)shape biotic interactions within ecosystems: Experimental evidence from the freshwater cnidarian Hydra

Authors: Justine Boutry; Juliette Mistral; Laurent Berlioz; Alexander Klimovich; Jácint Tökölyi; Laura Fontenille; Beata Ujvari; Antoine M. Dujon; Mathieu Giraudeau; Frédéric Thomas

Source: Science of The Total Environment (AUG 2021)


While it is often assumed that oncogenic processes in metazoans can influence species interactions, empirical evidence is lacking.

Here, we use the cnidarian Hydra oligactis to experimentally explore the consequences of tumor associated phenotypic alterations for its predation ability, relationship with commensal ciliates and vulnerability to predators.

Unexpectedly, hydra’s predation ability was higher in tumorous polyps compared to non-tumorous ones. Commensal ciliates colonized preferentially tumorous hydras than non-tumorous ones, and had a higher replication rate on the former.

Finally, in a choice experiment, tumorous hydras were preferentially eaten by a fish predator. This study, for the first time, provides evidence that neoplastic growth has the potential, through effect(s) on host phenotype, to alter biotic interactions within ecosystems and should thus be taken into account by ecologists.

Graphical abstract

Is There One Key Step in the Metastatic Cascade?

Authors: Antoine M. Dujon, Jean-Pascal Capp, Joel S. Brown, Pascal Pujol, Robert A. Gatenby, Beata Ujvari, Catherine Alix-Panabières and Frédéric Thomas

Source: Evolutionary Applications (MAY 2021)

Brief summary of the paper:

Simple Summary

To successfully metastasize, cancer cells must complete a sequence of obligatory steps called the metastatic cascade. To model the metastatic cascade, we used the framework of the Drake equation, initially created to describe the emergence of intelligent life in the Milky way, using a similar logic of a sequence of obligatory steps.

Then within this framework, we used simulations on breast cancer to investigate the contribution of each step to the metastatic cascade.

We show that the half-life of circulating tumor cells is one of the most important parameters in the cascade, suggesting that therapies reducing the survival of those cells in the vascular system could significantly reduce the risk of metastasis.


The majority of cancer-related deaths are the result of metastases (i.e., dissemination and establishment of tumor cells at distant sites from the origin), which develop through a multi-step process classically termed the metastatic cascade.

The respective contributions of each step to the metastatic process are well described but are also currently not completely understood. Is there, for example, a critical phase that disproportionately affects the probability of the development of metastases in individual patients?

Here, we address this question using a modified Drake equation, initially formulated by the astrophysicist Frank Drake to estimate the probability of the emergence of intelligent civilizations in the Milky Way. Using simulations based on realistic parameter values obtained from the literature for breast cancer, we examine, under the linear progression hypothesis, the contribution of each component of the metastatic cascade. Simulations demonstrate that the most critical parameter governing the formation of clinical metastases is the survival duration of circulating tumor cells (CTCs).

COVID-19 disruption reveals mass-tourism pressure on nearshore sea turtle distributions and access to optimal breeding habitat

Authors: Gail Schofield, Liam C. D. Dickson, Lucy Westover, Antoine M. Dujon & Kostas A. Katselidis

Source: Evolutionary Applications (MAY 2021)

Brief summary of the paper:

Quantifying the extent to which animals detect and respond to human presence allows us to identify pressure (disturbance) and inform conservation management objectively; however, obtaining baselines against which to compare human impact is hindered in areas where human activities are already well established.

For example, Zakynthos Island (Greece, Mediterranean) receives around 850,000 visitors each summer, while supporting an important loggerhead sea turtle rookery (~300 individuals/season).

The coronavirus (COVID-19)-driven absence of tourism in May–June 2020 provided an opportunity to evaluate the distribution dynamics of this population in the absence (2020) vs. presence (2018 and 2019) of visitors using programmed unmanned aerial system (UAS) surveys.

Ambient sea temperature transitioned from suboptimal for breeding in May to optimal in late June, with turtle distribution appearing to shift from shallow (to benefit from waters 3–5°C above ambient) to deeper waters in 2018 and 2019, but not 2020. The 2020 data set demonstrated that increased tourism pressure, not temperature, drives turtles offshore.

Specifically, >50% of turtles remained within 100 m of shore at densities of 25–50 visitors/km, even when sea temperature rose, with 2018 and 2019 data supporting this trend. Reduced access to warmer, nearshore waters by tourism could delay the onset of nesting and increase the length of the egg maturation period between nesting events (internesting interval) at this site. A coastal refuge zone could be delimited in May–June where touristic infrastructure is minimal, but also where turtles frequently aggregate.

In conclusion, sea turtles appear capable of perceiving changes in the level of human pressure at fine spatial and temporal scales and adjusting their distribution accordingly.

Genetic structure and gene flow in the Flame Robin (Petroica phoenicea)

Authors: Beckmann, C; Major, RE; Frankham, GJ; Thomas, S; Biro, PA; Ujvari, B; Neaves, L


Brief summary of the paper:

Robins in the family Petroicidae are characteristic of the woodland bird community that is threatened in Australia as a result of habitat loss and fragmentation. Flame Robin (Petroica phoenicea) populations declined by 56% between 1980 and 2000, with habitat loss likely being the primary cause.

Given that Flame Robins primarily breed at high elevation, populations may become more isolated due to anthropogenic change, resulting in increased inbreeding and loss of genetic diversity that may accelerate local extinction.

We estimated the genetic structure and recent gene flow among four populations (n = 70 birds) of this vulnerable (NSWSC) species across a 670 km portion of its range in temperate south-eastern Australia using 14 genetic markers. We found no significant differences in genetic diversity amongst populations and little population structuring – only the northernmost population showing a weak signal of differentiation. However, we detected little recent migration between the northern and southern sites, possibly due to recent fragmentation.

We conclude that habitat loss is a conservation concern for this Vulnerable species and further work and ongoing genetic monitoring is needed, particularly given high elevation breeding sites that are vulnerable in the face of a changing climate.

Does Cancer Biology Rely on Parrondo’s Principles?

Authors: Jean-Pascal Capp, Aurora M Nedelcu, Antoine M Dujon, Benjamin Roche, Francesco Catania, Beata Ujvari, Catherine Alix-Panabières and Frédéric Thomas

Source: CANCERS (MAY 2021)

Brief summary of the paper:

Many aspects of cancer biology remain puzzling, including the proliferative and survival success of malignant cells in spite of their high genetic and epigenetic instability as well as their ability to express migrating phenotypes and/or enter dormancy despite possible fitness loss.

Understanding the potential adaptive value of these phenotypic traits is confounded by the fact that, when considered separately, they seem to be rather detrimental at the cell level, at least in the short term. Here, we argue that cancer’s biology and success could frequently be governed by processes underlying Parrondo’s paradox, whereby combinations of intrinsically losing strategies may result in winning outcomes.

Oncogenic selection would favor Parrondo’s dynamics because, given the environmental adversity in which malignant cells emerge and evolve, alternating between various less optimal strategies would represent the sole viable option to counteract the changing and deleterious environments cells are exposed to during tumorigenesis.

We suggest that malignant processes could be viewed through this lens, and we discuss how Parrondo’s principles are also important when designing therapies against cancer.

A review of the potential effects of climate change on disseminated neoplasia with an emphasis on efficient detection in marine bivalve populations

Authors: Georgina Bramwell, Aaron G. Schultz, Craig D. H. Sherman, Mathieu Giraudeau, Frédéric Thomasb, Beata Ujvari, Antoine M Dujon


Brief summary of the paper:

Climate change not only directly impacts marine environments by shifting water temperatures, salinity, pH and dissolved oxygen concentrations, but may also indirectly contribute to the emergence of additional ecosystem stressors, such as infectious diseases, including bivalve disseminated neoplasia.

Disseminated neoplasia, a form of cancer found in some bivalves – recently discovered to be transmissible in at least six species – has been shown to impair bivalve health and fitness, with occasional mass outbreaks causing high levels of mortality. As the ability of the host bivalve to respond to disseminated neoplasia, and the survival and transmissibility of disseminated neoplasia both depend on environmental factors, it is crucial to understand the interaction between climate change and disseminated neoplasia epidemiology.

Furthermore, with bivalves being species of high ecological and economic importance, there is a rising need for the development of efficient disseminated neoplasia diagnostic tools in order to detect, mitigate and potentially prevent deleterious disseminated neoplasia outbreaks.

Therefore, in this study, we reviewed the current knowledge of climate impacted environmental parameters on disseminated neoplasia and identified best practices and methodology for the detection of transmissible disseminated neoplasia in the wild.

By exploring the potential effects changing climate has on disseminated neoplasia dynamics, we identified future research directions in order to advance the field. This included using state of the art disease detection methods and taking into account species’ ecological niches to understand the dynamic of disseminated neoplasia outbreaks in the wild and to investigate whether disseminated neoplasia is present in freshwater ecosystems.

Finally, we provided a comprehensive step-by-step guideline for an evidence-based detection of this disease in marine ecosystems.

Group phenotypic composition in cancer

Authors: Jean-Pascal Capp, James DeGregori, Aurora M Nedelcu, Antoine M Dujon, Justine Boutry, Pascal Pujol, Catherine Alix-Panabières, Rodrigo Hamede, Benjamin Roche, Beata Ujvari, Andriy Marusyk, Robert Gatenby, Frédéric Thomas

Source: eLife (MAR 2021)

Brief summary of the paper:

Although individual cancer cells are generally considered the Darwinian units of selection in malignant populations, they frequently act as members of groups where fitness of the group cannot be reduced to the average fitness of individual group members.

A growing body of studies reveals limitations of reductionist approaches to explaining biological and clinical observations. For example, induction of angiogenesis, inhibition of the immune system, and niche engineering through environmental acidification and/or remodeling of extracellular matrix cannot be achieved by single tumor cells and require collective actions of groups of cells. Success or failure of such group activities depends on the phenotypic makeup of the individual group members.

Conversely, these group activities affect the fitness of individual members of the group, ultimately affecting the composition of the group. This phenomenon, where phenotypic makeup of individual group members impacts the fitness of both members and groups, has been captured in the term ‘group phenotypic composition’ (GPC).

We provide examples where considerations of GPC could help in understanding the evolution and clinical progression of cancers and argue that use of the GPC framework can facilitate new insights into cancer biology and assist with the development of new therapeutic strategies.