作为新兴的肿瘤组分，肿瘤内细菌已经在许多实体肿瘤中被发现。多项研究已经表明，不同的癌症亚型拥有不同的微生物组成，机制研究也表明，肿瘤内菌可以通过 DNA 损伤、表观遗传修饰、炎症反应、调节宿主免疫和激活癌基因或致癌通路来促进癌症的发生和进展。此外，肿瘤内细菌已被证明可以调节肿瘤转移和化疗反应。更好地了解肿瘤微环境及其相关微生物群落将有助于设计新的代谢工程菌株，开启肿瘤内细菌为基础的癌症治疗新时代。然而，许多问题仍需解决，比如肿瘤内细菌的起源和是否存在肿瘤易感性与肿瘤内细菌之间的直接因果关系。此外，适合的临床前模型和更先进的检测技术对于研究肿瘤内细菌的生物学功能至关重要。在本综述中，我们总结了肿瘤内细菌在调节癌症发展和转移中的复杂作用，并讨论了它们的致癌机制和潜在治疗方面。版权所有 © 2022 Elsevier B.V.

As emerging tumor components, intratumoral bacteria have been found in many solid tumors. Several studies have demonstrated that different cancer subtypes have distinct microbial compositions, and mechanistic studies have shown that intratumoral bacteria may promote cancer initiation and progression through DNA damage, epigenetic modification, inflammatory responses, modulation of host immunity and activation of oncogenes or oncogenic pathways. Moreover, intratumoral bacteria have been shown to modulate tumor metastasis and chemotherapy response. A better understanding of the tumor microenvironment and its associated microbiota will facilitate the design of new metabolically engineered species, opening up a new era of intratumoral bacteria-based cancer therapy. However, many questions remain to be resolved, such as where intratumoral bacteria originate and whether there is a direct causal relationship between intratumoral bacteria and tumor susceptibility. In addition, suitable preclinical models and more advanced detection techniques are crucial for studying the biological functions of intratumoral bacteria. In this review, we summarize the complicated role of intratumoral bacteria in the regulation of cancer development and metastasis and discuss their carcinogenic mechanisms and potential therapeutic aspects.Copyright © 2022 Elsevier B.V. All rights reserved.