The Mechanism and Pathways of Formation and Modification of Salivary Metabolic Profile in Cancer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript addresses an important and timely topic about how saliva reflects cancer-associated systemic and local biological changes, and whether salivary metabolites, cytokines, tumor markers, and microbiome alterations can support cancer diagnosis or monitoring. The review is overall based on a strong conceptual framework, but the manuscript currently reads more like a broad mechanistic essay than a rigorous systematic/narrative review. Several sections need more tightening, clearer evidence grading, improved structure, and more critical discussion of limitations. The areas requiring improvement are as follows:

 

1. A recurring issue is that probable biological pathways are presented alongside clinically demonstrated findings without enough distinction. For example, the manuscript states that distant tumors may influence saliva through:

• cytokines
• extracellular vesicles
• systemic inflammation
• metabolic remodelling

This is a biologically possible and supported conceptually. However, the strength of evidence differs greatly between:

• Oral cancers, where tumor material directly contacts saliva
• Distant cancers, where multiple intermediate processes occur

The review should add a table such as:

Biomarker/pathway	Oral cancer evidence	Distant cancer evidence	Clinical maturity
IL-8	Strong	Moderate/uncertain	Research
Exosomal RNA	Emerging	Emerging	Experimental
Electrolytes	Weak	Weak	Not diagnostic

This would greatly improve scientific balance.

2. The electrolyte discussion is detailed, but the manuscript itself acknowledges that electrolyte changes are low-specificity indicators.

The section could be shortened and reframed:

• explain physiology briefly
• discuss cancer-associated changes
• emphasize confounding factors:
• hydration
• medications
• renal function
• diet
• collection method

The current length may give electrolytes more importance than justified.

3. For introduction add a figure showing:

Cancer → systemic inflammation → salivary gland response → saliva alteration

VS

Oral tumor → direct saliva exposure → biomarker release

This distinction is central.

4. The amino acid section is scientifically interesting, but overly detailed in biochemical pathways. The discussion of glutamine, tryptophan, BCAA metabolism, mTORC1, TCA cycle, etc., is informative. However, the connection to actual salivary measurements needs more emphasis.

Suggested structure:

• Cancer metabolic changes
• How they alter plasma amino acids
• How saliva reflects these changes
• Clinical evidence

5. In the lipid section

• distinguish lipid biomarkers from lipid-mediated mechanisms

• avoid implying causation where only association exists

6. In the microbiome section discuss:

• sequencing methods
• contamination issues
• whether dysbiosis is a cause or consequence of cancer/treatment

8. Figures need stronger integration:

• Figure 1: useful, but should distinguish evidence-supported pathways from hypothetical pathways.
• Figure 2: interesting model but should be labeled as conceptual.

 

9. Add a final table: “Current status of salivary cancer biomarkers” that includes:

• marker
• cancer type
• biological source
• evidence level
• clinical readiness

Comments on the Quality of English Language

Language needs editing:

• “aquareporins” → likely “aquaporins”
• “interferon’s” → “interferons”
• Avoid repeated statements that individual biomarkers lack specificity; this point appears many times.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript discusses the mechanisms underlying changes in the salivary metabolic profile in cancer and their potential diagnostic implications. The review is generally well organized and covers a broad range of relevant literature. I found the manuscript informative; however, several sections would benefit from a more critical discussion rather than a descriptive summary of published studies. I believe the points below would further strengthen the review.

1. Several sections, particularly the discussion of tumor markers, are largely descriptive. I encourage the authors to provide a more critical evaluation of the available evidence and to highlight the most promising biomarkers supported by independent validation.
2. The discussion of clinical translation is rather limited. Important issues such as sample standardization, pre-analytical variability, large-scale validation, and comparison with established blood-based biomarkers deserve greater attention.
3. The role of the microbiome could be integrated more closely with the other biomarker classes. Briefly discussing how microbial activity influences metabolites, cytokines, and related salivary components would strengthen the overall framework.
4. A concise section summarizing the most promising biomarker candidates and the key priorities for future research would improve the practical value of the review.
5. As a minor point, please check the reference list and terminology for consistency. Several references appear to require formatting verification, and terms such as salivaomics should be defined at first mention.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf