Distinct changes in lung microbiome precede clinical diagnosis of lung cancer

The comparison of the airway microbiome of cancer patients, incident-cancer patients, and people without cancer demonstrated that a specific shift in microbiota species preceded cancer development [1].

The tumour microenvironment (TME) has demonstrated importance to lung cancer biology. In particular, the presence of specific bacterial species in the gut has been associated with a response to checkpoint blockade in lung cancers [2]. It is possible that, in addition to their immune modulatory effect, commensal microbes may also secrete modulators or generate metabolites to potentiate tumour cells sensitivity to apoptosis induction and, thereby, rendering cancer patient response to ICI immunotherapy [3]. Nowadays, it has been shown that bacterial communities are different in the tumour compared with the surrounding non-malignant cells. One of the reasons for the poor survival in lung cancer is late disease detection. The presence of certain bacteria in the airways could serve as an indicator for lung cancer development. At present, it is unclear at what stage during cancer development this bacterial shift occurs.

To assess the role of the microbiota in cancer development PhD candidate Erin Marshall (University of British Columbia, Canada) and her team analysed the airway microbiota after bronchoscopy in a cohort of high-risk patients: 3 participants were shown to have current cancer, 40 had no cancer, and 5 developed cancer in a follow-up period of 9.2 years (i.e. the incident cancer group).

An analysis of the diversity of the microbiome revealed a cluster of cancer and incident-cancer patient samples compared with the patients with no cancer. This suggests that the microbiome of patients who will develop cancer in a time frame of 3 months to 4.5 years exhibits similarity to the microbiome of patients who already have clinically detectable cancer. In a second cohort, the researchers found a relative abundance of Bacilli/Lactobacillales in participants who went on to develop cancer during the follow-up period. In addition, the Paenibacillaceae family increased in patients with incident cancer and cancer. This facultative anaerobe genus is a known opportunistic infector of humans. Its abundance is associated with a wide variety of diseases including cancers such as gastric cancer. In addition, it is commonly observed in immunocompromised patients, for example, in the elderly and in those with weak immune systems. The analysis further showed 5 pathways significantly associated with incident-cancer patient airways: the deregulation of RNA transport, taurine and hypotaurine metabolism, linoleic acid metabolism, and the formation of biofilm.

The authors concluded that bacteria in non-malignant airway cells may be associated with cancer initiation. Distinct microbiome profiles in the airways can identify patients that develop incident cancers. “While preliminary, this work indicates the possible future role of microbiome in lung cancer prediction and screening,” concluded Ms Marshall.

 

1. 
   
   1. Marshall EA, et al. Distinct Lung Microbiome Preceding Clinical Diagnosis of Lung Cancer. A4249. ATS Virtual Congress 2020, 5-10 August.
   2. Elkrief A, et al. Gut Microbes 2019; 10: 424-428.
   3. Liu K, Lu C. Transl Cancer Res 2018;7(Suppl 5): S 608-10.

 



Posted on 29 October 202023 April 2024