Ageing influences tumour–niche interactions: Implications for metastatic dormancy, reawakening and recurrence

Many cancer patients remain at risk of metastatic relapse for the remainder of their lives, despite initial disease remission, due to disseminated tumour cells (DTCs) persisting at secondary sites in a dormant, therapy-resistant state. Dormant DTCs can reawaken and develop into clinical metastasis after a prolonged latency period. Interactions between DTCs and their niche are key to metastatic dormancy and subsequent reawakening and outgrowth. Ageing has profound effects on tissues and the immune system and, as such, the field is evolving to delineate the impact of an aged microenvironment on metastatic dormancy. We summarise the latest insights in this review, focussing on recent advances in immune- and stroma-mediated regulation of dormancy and reawakening in the context of age-related microenvironmental perturbations.