This review by Sun and Chen discusses the recent advancements in hydrogel-based biosensors for cancer detection. Hydrogels, three-dimensional networks of hydrophilic polymers, offer promising alternatives for developing biosensors due to their high sensitivity, specificity, and stability. The review covers the synthesis, applications, and challenges of hydrogel-based biosensors in cancer detection. It highlights the potential of hydrogels in early cancer detection, which is crucial for effective treatment. The review also discusses the integration of hydrogels with various biosensing platforms, such as peptide, DNA, and conducting polymer hydrogels, and their advantages and limitations. Additionally, it explores the use of cell-based biosensors and engineered living hydrogels for cancer detection. The review emphasizes the need for further research to overcome challenges such as nonspecific binding, low conductivity, and the complexity of real human samples. Overall, the review provides a comprehensive analysis of the current state and future directions of hydrogel-based biosensors in cancer detection.This review by Sun and Chen discusses the recent advancements in hydrogel-based biosensors for cancer detection. Hydrogels, three-dimensional networks of hydrophilic polymers, offer promising alternatives for developing biosensors due to their high sensitivity, specificity, and stability. The review covers the synthesis, applications, and challenges of hydrogel-based biosensors in cancer detection. It highlights the potential of hydrogels in early cancer detection, which is crucial for effective treatment. The review also discusses the integration of hydrogels with various biosensing platforms, such as peptide, DNA, and conducting polymer hydrogels, and their advantages and limitations. Additionally, it explores the use of cell-based biosensors and engineered living hydrogels for cancer detection. The review emphasizes the need for further research to overcome challenges such as nonspecific binding, low conductivity, and the complexity of real human samples. Overall, the review provides a comprehensive analysis of the current state and future directions of hydrogel-based biosensors in cancer detection.