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Page 8 of 17 Sharma et al. Microbiome Res Rep 2024;3:3 https://dx.doi.org/10.20517/mrr.2023.51

[66]
increased level of lactic acid fermentation and elevated secretion of lactate . This increased lactate
stimulates cell proliferation and suppresses the antitumor activity, in turn promoting cell angiogenesis and
metastasis. The overproduction of lactate would impair the efficacy of chemotherapy by accelerating tumor
angiogenesis, immune evasion, metastasis, and epithelial-mesenchymal transition (EMT). Therefore, we can
safely assume that the dysbiotic population of Bifidobacterium is involved in the failure of chemotherapy
against ovarian cancer.

All these data regarding the role of bifidobacteria in various cancers shed light on its dysbiotic population in
the gut. It is surely clear that there is insufficient substantial evidence regarding the gut bifidobacteria
diversity in various types of cancers, but the already reported dysbiotic population should not be ignored. It
indicates a potential danger towards the development of malignancies and their progression [Figure 2].

BIFIDOBACTERIUM IN CONVENTIONAL CANCER THERAPY
Conventional cancer therapies broadly consist of surgical treatment and tumor removal by cauterization
along with radiotherapy and/or chemotherapy for treating different kinds of tumors, such as hematological
or solid tumors. The persistently evolving drug treatments for cancer and therapies have paved the way for
[67]
the treatment of cancer via deeply innovative biotechnological, chemical, and biological drugs .
Due to its ability to intensify the cancer cell apoptosis and shield against oxidative stress, the presence of
Bifidobacterium in probiotics can potently induce anticancer effects. The combinative administration of
probiotics along with anticancer drugs showed greater efficacy of antitumor activity in colorectal cancer.
The common side effects caused by chemotherapy and radiation therapy, such as Chemotherapy-induced
diarrhea (CID), mucositis, and Radiation-induced diarrhea (RID), were significantly reduced when
probiotics containing Bifidobacterium bifidum were administered. Strains, namely B. infantis, B. longum,
and B. breve, decreased proinflammatory cytokine levels when treated with 5-fluorouracil . The clinical
[68]
benefits of using B. breve probiotics were also seen in immunocompromised hosts during the chemotherapy
[69]
by showing internal stabilization of intestinal microflora throughout this period .
B. infantis impaired the severity of intestinal mucositis induced by chemotherapy . Probiotics containing
[70]
Bifidobacterium in combination with Lactobacillus, administrated as a 4-week post-surgical treatment for
colorectal cancer, showed no aggravation for diarrhea, and they demonstrated immunobiotic effects by
[71]
maintaining stable proinflammatory cytokine levels . The oral administration of the probiotic
bifidobacteria during the perioperative period of colorectal cancer resulted in a balanced ratio of intestinal
microbiota and led to a lower inflammatory response, thereby promoting accelerated and healthy recovery
post colorectal resection . Cancer patients suffering from functional constipation were given
[72]
Bifidobacterium tetragenous viable bacteria tablets along with chemotherapy, and the results indicated
[73]
effective treatment of functional constipation .
The pre-treatment of bifidobacterial strain B. infantis with its specific monoclonal antibody, when given in
combination with radiation therapy, resulted in increased efficacy of radiation therapy for lung cancer. It
particularly showed a delay in tumor growth, minimal toxicity, and prolonged survival in LLC xenograft
mouse models . Several research and clinical studies thus indicate that Bifidobacterium is vital in
[74]
enhancing the efficacy of conventional cancer therapies such as surgery, chemotherapy, and radiation
therapy when dispensed in combination with conventional therapies.