Tumor resection may abort the antitumor immune response produced from primary foci

Clinical observations suggest that after surgical removal of the primary tumor, metastases exhibit accelerated growth. This suggests that the primary tumor may exert inhibitory effects on micrometastases, and its surgical removal may conversely become a factor that is unfavorable for antitumor therapy. Proposed over a century ago, this phenomenon is linked to antitumor immune responses, known as concomitant immunity (CI), wherein the primary tumor suppresses secondary tumors through specific immune mechanisms. Subsequent studies have investigated the patterns and mechanisms of CI, facilitating the development of novel targets and treatment strategies for suppressing metastasis. This review traces the evolution of CI theory, summarizes the latest mechanisms underlying its antitumor effects, examines how surgery disrupts CI, and discusses current therapeutic approaches leveraging CI principles. This review focuses on CI to provide a theoretical basis for understanding postoperative recurrence mechanisms and developing novel anti-metastatic strategies.