Fig. 1

Modifications in the lung microenvironment occurring during the early and severe phases of SARS-CoV-2 infection and potentially involved in the reawakening of dormant breast cancer cells (DBCCs). During the early phase of COVID-19 (left), SARS-CoV-2 enters pulmonary alveoli and infects airway epithelial cells, which undergo cell death releasing damage-associated molecular patterns (DAMPs). DAMPs activate neighboring cells, starting an inflammatory response that in the severe phase of the disease (right) results in an overproduction of inflammatory cytokines and recruitment of activated monocytes, macrophages, and neutrophils. The latter produces neutrophil extracellular traps (NETs), which contribute to inflammation, immune escape, and thrombosis. NETs, and possibly pro-inflammatory cytokines, can cause DBCC reawakening leading to metastatic outgrowth and tumor relapse