Quiescent cancer cells (QCCs) are recognized as a source of cancer recurrence and pose a significant challenge in cancer treatment. Following anti-cancer therapy, non-proliferating, therapy-resistant QCCs have been detected in subsets of residual cancer cells within patients' bodies. Clinicians and researchers widely acknowledge that these minimal residual QCCs can eventually regain proliferative activity, acting as "seeds" for cancer recurrence.
Despite the significance of QCCs, tracing and analyzing these microscopic residual cells in vivo models and patients remains extremely challenging, limiting our understanding. Consequently, reliable biomarkers for QCCs and the mechanisms underlying their ‘reversible’ reactivation remain poorly understood. This knowledge gap has hindered the development of diagnostics and targeted therapies for QCCs. The absence of diagnostic tools for QCCs also complicates predicting cancer relapse and determining the optimal duration of anti-cancer treatment. Furthermore, without strategies to eradicate QCCs, the prevention of cancer recurrence remains elusive.
This review aims to provide an overview of the current understanding of QCCs and related diagnostic efforts in both basic and clinical research. Additionally, potential strategies for the targeted elimination of QCCs are explored. Focused research and clinical attention on diagnosing and eradicating residual QCCs are essential for preventing cancer recurrence and ultimately conquering this deadly disease.