Cancer remains a leading global cause of death, with over 20 million new cases and more than ten million deaths annually, disproportionately burdening low- and middle-income countries due to late-stage diagnosis and limited access to treatment. A concerning rise in early-onset cancers, particularly in individuals under 50 years of age, is linked to prenatal exposure, diet, and lifestyle factors. While cancer mortality has decreased by 33% since 1991 due to advances in immunotherapy and early detection, the incidence continues to rise with population aging. Metastatic disease accounts for approximately two-thirds of cancer deaths, primarily via organ failure or systemic inflammation. The variability in survival among metastatic cancers and emerging hypotheses linking cancer to accelerated aging underscore the need for a systemic understanding of cancer lethality. Lessons from the COVID-19 pandemic offer a novel perspective on cancer pathophysiology. Despite widespread infection, mortality from COVID-19 is primarily restricted to elderly or individuals with comorbidities, implicating biological age, immune senescence, and systemic frailty as key determinants of outcome. Analogously, cancer mortality is more closely associated with comorbidity burden and biological age rather than with chronological age. Notably, cancer incidence declines in centenarians, possibly due to protective immune phenotypes and nonpermissive systemic environments. Both cancer and COVID-19 highlight the role of systemic inflammation—acute or chronic—as a common pathway to mortality. These parallels challenge traditional “tumor-centric” models of disease, suggesting a shift toward “host-centric” frameworks. Understanding mortality as an emergent property of interactions between pathological triggers and the host’s systemic resilience opens new avenues for prognostication and integrative, host-targeted therapies.