Concomitant [[immunity]] refers to a situation in natural host-parasite relationships, namely that [[host]]s already infected with a [[parasite]] are partially or wholly resistant to reinfection with the “homologous” organism.
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An apparent [[paradox]] exists between the evidence for spontaneous systemic [[T cell]]-mediated anti-tumor [[immune response]]s in [[cancer]] patients, observed particularly in their [[bone marrow]], and local [[tumor growth]] in the periphery. This phenomenon, known as "[[concomitant immunity]]" suggests that the local tumor and it's [[tumor microenvironment]] (TME) prevent systemic [[antitumor immunity]] to become effective.