Saliva Test May Detect One of South Africa’s Deadliest and Most Mysterious Cancers Sooner

Scientists at the Sydney Brenner Institute for Molecular Bioscience (SBIMB) at Wits University are delving into an intriguing and potentially transformative avenue of research that explores the microbial populations present in saliva as a low-cost and non-invasive biomarker for oesophageal squamous cell carcinoma (ESCC). This cancer subtype is notorious for its late diagnosis, which frequently limits therapeutic options to palliative care, thus highlighting an urgent need for earlier detection methods that can improve survival outcomes.

ESCC is distinct from oesophageal adenocarcinoma, the latter being strongly correlated with well-known risk factors such as acid reflux, obesity, and lifestyle habits prevalent in developed nations. Conversely, ESCC disproportionately affects populations in specific geographic regions, including parts of China, Iran, and notably the eastern regions of Africa such as South Africa’s Eastern Cape and KwaZulu-Natal provinces. This geographical clustering raises significant questions surrounding underlying causative factors, which remain elusive despite extensive investigation.

One of the most perplexing features of ESCC is its occurrence in notably younger patients, with a mean diagnosis age around 50 years and nearly one-fifth of cases detected in individuals under 40. This premature manifestation, coupled with geographic and demographic disparities, underscores a potentially unique etiologic profile distinct from other oesophageal cancers. Professor Christopher Mathew, a distinguished scientist at SBIMB, has emphasized the gap in epidemiological data specific to ESCC, which hampers comprehensive understanding and effective early intervention strategies.

Dr. Wenlong Carl Chen and his team have made significant strides by leveraging data from the Johannesburg Cancer Study to reaffirm that traditional risk factors, including tobacco smoking, heavy alcohol consumption, lower socioeconomic status, and use of biomass fuels for cooking and heating, contribute to ESCC risk but do not completely account for the disease’s incidence patterns. This residual uncertainty necessitates novel investigative methods beyond conventional epidemiology, directing attention to the role of oral microbiota.

A recent landmark study published in Communications Medicine, developed through an international collaboration between SBIMB and Columbia University, demonstrates that the composition of bacteria in saliva differs markedly between ESCC patients and healthy controls. Employing advanced genetic sequencing techniques alongside sophisticated machine-learning algorithms, researchers identified distinctive microbial signatures associated with the cancer. These findings suggest the oral microbiome could serve as a biomarker for the disease, offering a groundbreaking approach to risk stratification in diverse populations.

Intriguingly, bacteria such as Fusobacterium nucleatum, previously implicated in other malignancies like colorectal cancer, were found in higher abundance in the saliva of ESCC patients. Though it remains to be definitively proven whether these microbial alterations contribute causally to carcinogenesis or represent an epiphenomenon resulting from tumor-related esophageal changes, their presence provides a compelling diagnostic clue. The analogy of a blocked kitchen sink accumulating debris captures the possibility that microbial shifts may reflect early obstructive changes in the oesophagus preceding clinical diagnosis.

The practical implications of this discovery lie in developing saliva- or cheek-swab-based diagnostic tests that could serve as triage tools, particularly for resource-limited settings with high ESCC prevalence. While such biomarkers would not supplant the gold standard of endoscopic examination, they could enable targeted referral of individuals demonstrating microbial patterns indicative of esophageal distress, thus facilitating earlier clinical intervention and potentially improving patient outcomes.

Globally, oesophageal cancer remains a major health burden with over 600,000 new cases and more than 540,000 deaths annually, many of which occur in areas characterized by limited healthcare infrastructure and high ESCC prevalence. Consequently, innovations like microbiome-based detection carry significant promise for addressing healthcare disparities by introducing affordable, scalable screening modalities.

The researchers emphasize that these findings represent an early but critical foundation. Validation of the microbial model across independent cohorts, particularly those from varied geographic and ethnic contexts, is essential to ensure generalizability given known variability in microbiome composition influenced by diet, environment, and genetics. As such, enactment of large-scale, multi-center studies incorporating genomics, environmental exposure assessments, and community engagement are priority next steps in elucidating the complex etiology of ESCC.

Beyond microbial profiling, expanding research to explore inherited genetic susceptibilities and characterization of tumor mutation signatures could yield complementary insights. Tumor mutational analyses can serve as molecular archives recording exposure to carcinogens such as environmental pollutants or dietary toxins, offering a novel framework for understanding how specific etiologic factors contribute to tumorigenesis in susceptible populations.

This multifaceted approach, championed by scientists at SBIMB and their global collaborators, holds promise for unraveling the mysteries of ESCC and transitioning from observational knowledge to clinical utility. Professor Michèle Ramsay, Director of the SBIMB, highlights the transformative potential of this research pipeline to ultimately enhance early detection, tailor preventive strategies, and reduce the heavy morbidity and mortality associated with oesophageal squamous cell carcinoma worldwide.

As new cohorts including confirmed ESCC cases, benign oesophageal condition patients, and healthy controls are enrolled, the scientific community eagerly anticipates whether saliva-based microbial signatures will prove effective in distinguishing malignant from non-malignant esophageal abnormalities. This work exemplifies the cutting-edge intersection of molecular biosciences, epidemiology, and data science poised to redefine cancer diagnostics and offer hope for improved outcomes in an under-studied yet devastating disease.

News Publication Date:
28-Feb-2026.

Web References:
Nature Article DOI: 10.1038/s43856-026-01468-y