Associations between neoplasia incidence and telomere biology
We found that the prevalence of neoplasia is a good predictor of malignancy prevalence (R2=0.90, β=0.7735±0.0489, p<0.001, Fig. S2) across 29 mammal species included in Boddy et al. (2020). Because neoplasia prevalence was available for more species, analyses proceeded using this variable.
As expected, neoplasia rate was positively associated with TL (Fig. 3a) and binary telomerase activity (Fig. 3d, marginally significant trend) across the 22 mammal species shown in Table S9. Thus, a 1% increase in TL predicts an absolute increase in neoplasia incidence of 0.21% (Fig. 3a). Neoplasia rate was negatively associated with lifespan (Fig 3b). A 1% increase in maximum lifespan predicts an absolute decrease in neoplasia incidence of 0.14% (Fig. 3b). Species with some telomerase activity (1) are predicted to show an absolute increase in neoplasia incidence of 20.6% (Fig. 3d). There was no association between neoplasia rate and mass (Fig. 3c). There was a marginal significant positive association between TL and neoplasia rate, when accounting for binary telomerase activity (Table 2).
Neoplasia rates could be biased towards higher estimates in domesticated species due to the easier observation of large numbers of individuals (Nagy et al., 2007; Ewald & Ewald, 2015; Boddy et al., 2020), which could be associated with increased lifespan and senescence in captivity (Tidière et al., 2016). We therefore tested, in a post hoc analysis, whether the effect of TL on neoplasia rate was robust to controlling for potential domestication effects on neoplasia rates (Table S6) or if the effect of TL varied with domestication status (Table S7). TL remained significantly positively associated with neoplasia rate when controlling for domestication status and there was no effect of domestication status on neoplasia rate (Table S6). The effect of TL on neoplasia rate did not vary with domestication status (Table S7).