Bacterial Microbes Linked to Head and Neck Cancer

Certain bacterial populations are increased or decreased in the presence of cancer.

Bacterial communities in the body were found to be associated with head and neck squamous cell carcinoma, which could present a tool in cancer diagnosis and treatment.

In a study by Johns Hopkins Medicine, researchers extracted bacterial DNA from the saliva of 42 patients. There were 17 samples taken from patients with head and neck squamous cell carcinoma, of which 7 were positive for HPV and 10 were HPV-negative. There were 25 noncancerous samples used as the control.

Once bacterial DNA was found in the saliva, it was sequenced and divided into groups of highly-related populations. After further analysis, researchers were able to determine the genus of bacteria that each group belonged to.

The study revealed that bacterial populations differed in the cancerous and noncancerous samples. Samples of patients with tumors showed increased populations of streptococcus, dialister, and veillonella genera, and decreased populations of neisseria, aggregatibacter, haemophilus, and leptotrichia genera, compared with the controls.

The tumor samples also showed an increased prevalence of lactobacillus genus, which was present in 9.1% of tumor samples and 0.1% in the controls.

“We see some specific bacterial populations that are increased or lost in the presence of cancer when compared to healthy controls,” said researcher Rafael Guerrero-Preston, PhD, MPH.

Researchers also found a correlation between the types of bacteria and patient HPV status.

Samples that were HPV-positive had an increase in gemellaceae, leuconostoc, and veillonella genera compared with samples that were HPV-negative. Veillonella genera was found to be present in 15% of HPV-positive tumor samples, and 9.4% of HPV-negative tumor samples.

Authors noted that the findings do not confirm a direct cause-and-effect link between any of the bacteria and head and neck cancer. More research needs to be done to distinguish between the detection of bacterial DNA and the effects of the bacteria themselves.

If the study’s findings are confirmed in additional studies, physicians may be able to use the same sequencing tools from the study to quickly and accurately diagnose patients based on the bacteria in their mouths.

“One of the goals of our research is to better understand how the microbiome may influence the immune response to cancer and how the immune response affects the microbiome in turn,” Guerrero-Preston said. “Our findings suggest that we may one day use the composition of the microbiome to test for disease.”