Surgery, chemotherapy and radiotherapy are the conventional cancer treatments. Molecular targeted therapy is taken as a promising cancer treatment strategy owing to molecular targeted drugs, such as small molecular compounds or monoclonal antibodies drugs, with higher efficacy and fewer adverse effects compared with conventional treatments. However, many tumors are very heterogeneous and contain cancer stem cells, which increase the risk of cancer targeted therapy, leading to a lower efficacy cancer treatment. Based on the facts: Hypoxic environment exists in the center of solid tumors, which has previously regarded as a source of resistance to chemotherapy and radiotherapy. Hypoxic area is a common feature in all types of tumors and facilitates anaerobic bacteria to localize in this zone. These provide the rationale for targeted therapy by using a probiotic anaerobic bacterium including Bifidobacterium. Probiotic Bifidobacterium can locate and growth in the hypoxic area of solid tumors. Therefore, genetic modified Bifidobacterium containing target genes would be used as a very useful tool for cancer treatment, which could make the hypoxic area not be“a forbidden area”. In this review, we will discuss the reason that hypoxic area forms in the solid tumor, the way to use Bifidobacterium as cancer treatment tool, and its related issues including the biosafety, targeted localization, potential application and challenges of genetic modified Bifidobacterium.
