This review synthesizes rare upper-gastrointestinal tumor subtypes including squamous variants, lymphoepithelioma-like, adenosquamous, and neuroendocrine carcinomas. Their biology and biomarkers may differ from common cancers, but evidence is mainly small series and treatment is often extrapolated from adenocarcinoma or squamous carcinoma, leaving no single validated algorithm.
Key findings
- Several rare entities show aggressive behavior and distinct molecular features, yet prospective data are scarce and treatment is extrapolated from common histologies. The authors advocate genomic profiling, immune characterization, and biomarker-driven stratification to refine diagnosis and precision therapy.
Why this matters globally
Granular classification can support multicenter registries and basket trials for small populations, but molecular findings must demonstrate clinical actionability rather than alteration detection alone.
Thai researcher contribution
Nattaya Teeyapun of Chulalongkorn University contributed to an international pathology-oncology synthesis; this is scholarly collaboration, not a Thai patient cohort.
Limitations to consider
As a narrative review, it is vulnerable to selection and publication bias, with no reported search or appraisal method. The entities are highly heterogeneous and evidence is mostly noncomparative; therapeutic vulnerabilities often derive from biology or small reports rather than confirmatory trials.