Validation of the Association Between the Abundance of Three Bacterial Genera in Stool Samples and the Risk of Gallbladder Cancer in South American Patients With Gallstones

June 3, 2026 updated by: Centre Paul Strauss
In our previous work, we found three types of bacteria in stool samples from South American patients with gallstones linked to a higher risk of gallbladder cancer. The aim of the present study is to confirm these associations using a separate set of South American stool samples.

Study Overview

Status

Completed

Conditions

Detailed Description

Gallbladder cancer (GBC) is a highly lethal disease with a low incidence worldwide, but it is relatively frequent in indigenous populations of the Americas. The absence of specific symptoms and the lack of early detection tests often lead to delayed diagnosis and a very poor prognosis. Biomarkers identification for early detection are currently unavailable.

The gut microbiome plays an important role in the modulation of individual metabolic and immunologic functions. Although alterations in the gut microbiome have been reported in gallbladder cancer with several genera proposed as potential risk biomarkers, these findings remain largely exploratory and lack consistent validation across independent cohorts, particularly in populations with a high GBC incidence.

In our previous research, we carried out metagenomic sequencing of DNA extracted from faecal samples from 178 South American patients (n=48 with GBC and n=130 with gallstones) from the EULAT Eradicate GBC study. We found that the abundance of the bacterial genus Veillonella was higher, whilst that of Adlercreutzia and Gordonibacter was lower, in the faecal samples from GBC patients.

The aim of the present study is to validate the three identified associations using an independent set of South American stool samples (n=40 from GBC and n=80 from gallstone disease patients).

DNA extracted from the faecal samples will be pre-processed using Illumina DNA prep 1/4 for library preparation and sequenced on a NovaSeq X 25B 300c lane machine. Raw data will be pre-processed following a cleaning protocol with bbduk (bbmap-version 38.93). Cleaned reads will be analysed using the PathSeq pipeline in GATK (v4.1.6.0). Reads aligning to the human reference genome (GRCh38) will be removed, and remaining reads will be mapped to microbial reference databases obtained from the European Molecular Biology Laboratory (EMBL-Broad Institute). Analyses will be performed using established reference sets and default parameters, with a minimum clipped read length of 50.

Microbiome data will be analyzed using the R phyloseq framework. Batch effects will be assessed through Bray-Curtis distances and PERMANOVA, low-prevalence taxa (<10% of samples) will be filtered, and outliers identified via principal component analysis and Mahalanobis distance removed. Rarefaction will be applied to calculate Alpha diversity, while beta diversity will be assessed using Aitchison distance on CLR-transformed abundances. To validate the three associations identified, the newly generated bacterial abundances will be analysed using robust logistic regression (glmrob, robustbase R package), adjusting for potential confounding factors and correcting the probability values for multiple comparisons using the Bonferroni correction.

Study Type

Observational

Enrollment (Actual)

120

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Bolivia
      • Cochabamba, Bolivia
        • Caja Nacional de Seguro Social Cochabamba, Complejo Hospitalario Viedma, Instituto Gastroenterológico
  • Chile
      • Talca, Chile
        • Hospital Dr. Hernán Henriquez Aravena, Complejo Asistencial Padre las Casas, Hospital Regional de Talca, Hospital Regional de Concepción, Hospital Regional de Arica
  • Germany
      • Heidelberg, Germany
        • Statistical Genetics Research Group, Institute of Medical Biometry, University of Heidelberg
  • Peru
      • Arequipa, Peru
        • Instituto Regional de Enfermedades Neoplasicas del Sur (IREN SUR), Hospital Regional Honorio Delgado Espinoza, Hospital Goyeneche Arequipa, Hospital Regional Manuel Nuñez Butron-Puno

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

- Patients with gallstones and cancer-free OR - Patients with gallbladder cancer

Description

Inclusion Criteria:

  • Patients with gallstones and cancer-free OR - Patients with gallbladder cancer

Exclusion Criteria:

  • Antibiotics use

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
South American patients with gallbladder cancer
South American patients with gallstones, with no evidence of gallbladder cancer upon pathological ex

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Validation of the Association Between Gallbladder Cancer Risk in South American Patients With Gallstones and the Centered Log-Ratio-Transformed Abundance of Three Stool Bacterial Genera Determined by Shotgun Metagenomic Sequencing
Time Frame: Baseline
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Centre Paul Strauss

Collaborators

Statistical Genetics Research Group, Institute of Medical Biometry and Informatics, Heidelberg University of Heidelberg

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 1, 2019

Primary Completion (Actual)

January 31, 2026

Study Completion (Actual)

January 31, 2026

Study Registration Dates

First Submitted

May 11, 2026

First Submitted That Met QC Criteria

June 3, 2026

First Posted (Actual)

June 9, 2026

Study Record Updates

Last Update Posted (Actual)

June 9, 2026

Last Update Submitted That Met QC Criteria

June 3, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2026-010

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Unidentifiable patient data will be deposited in a public data repository after publication, data accession numbers will be provided in the article and upon request.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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