Cancer, a local disease at an early stage, systemically evolves as it progresses by triggering alterations in surrounding microenvironment, disturbing immune surveillance and further disseminating its molecular contents into circulation. This pathogenic characteristic of cancer makes the use of biofluids such as blood/serum/plasma, urine, tear and cerebrospinal fluids credible surrogates harboring tumor tissue-derived molecular alterations for the detection of cancer. Most importantly, a number of recent reports have credentialed the clinical validity of saliva for the detection of systemic diseases including cancers. In this review, we discussed the validity of saliva as credible biofluid and clinical sample type for the detection of cancers. We have presented the molecular constituents of saliva that could mirror the systemic status of our body and recent findings of salivaomics associated with cancers. Recently, liquid biopsy to detect cancer-derived circulating tumor DNA has emerged as a credible cancer-detection tool with potential benefits in screening, diagnosis and also risk management of cancers. We have further presented the clinical validity of saliva for liquid biopsy of cancers and a new technology platform based on electrochemical detection of cancer-derived ctDNA in saliva with superior sensitivity and point-of-care potential. The clinical utilities of saliva for the detection of cancers have been evidenced, but biological underpinning on the existence of molecular signatures of cancer-origin in saliva, such as via exosomal distribution, should be addressed in detail.

癌症是一种早期的局部疾病，随着病情的进展，会引发周围微环境的改变，扰乱免疫监视，并进一步将其分子内容物传播到循环系统中，从而发生系统性的演变。癌症的这种致病特征使得使用血液/血清/血浆、尿液、泪液和脑脊液等生物体液成为携带肿瘤组织衍生分子改变的可靠替代物来检测癌症。最重要的是，最近的一些报告证明了唾液用于检测包括癌症在内的全身性疾病的临床有效性。在这篇综述中，我们讨论了唾液作为可靠的生物流体和临床样本类型用于癌症检测的有效性。我们介绍了唾液的分子成分，可以反映我们身体的系统状态，以及与癌症相关的唾液组学的最新发现。最近，用于检测癌症来源的循环肿瘤 DNA 的液体活检已成为一种可靠的癌症检测工具，在癌症的筛查、诊断和风险管理方面具有潜在的益处。我们进一步展示了唾液用于癌症液体活检的临床有效性，以及基于电化学检测唾液中癌症来源的 ctDNA 的新技术平台，具有卓越的灵敏度和即时护理潜力。唾液用于检测癌症的临床效用已得到证实，但唾液中癌症起源分子特征（例如通过外泌体分布）存在的生物学基础应详细解决。