TABLE 1.

Tumor ecosystem paralleling to the Earth's biosphere

Ecology	Natural ecosystem	Artificial ecosystem	Tumor ecosystem
Biosphere	Earth	Earth	Patient
Ecosystem	Aquatic and terrestrial ecosystem	Urban ecosystem	Tissue and organ system
Metacommunities	Zoobenthos	Cities	Metastases
Species	Animals and plants	Humans	Cancer cells and host cells
Biotope	Water or land	Land	Extracellular matrix
Biogas	Swamp gas	Smoke and greenhouse gases	Cytokines, hormones and neurotransmitters
Abiotic factors	Land or water	Technology, transportation and infrastructure	Oxygen, acidity and therapeutic intervention
Energy source	Solar energy	Natural ecosystems	Food
Nutrient cycling	Biogeochemical cycling	Material supply and waste disposal	Intercellular signaling and metabolic interplay
Ecosystem collapse	Mass extinction	Urban pollution or mass migration	Organ failure and death