Gastrointestinal & Hepatobiliary Cancer
Gastrointestinal and hepatobiliary cancers form a group spanning the oesophagus to the anus, together with the liver, biliary tree and pancreas. Their molecular profiles differ substantially by site, which is why site-specific characterisation matters.
Disease categories
Major disease categories
- Oesophageal and gastric cancer
- Colorectal cancer
- Anal cancer
- Pancreatic cancer
- Liver and biliary tract cancer
- Neuroendocrine tumours of the gastrointestinal tract
Molecular
Molecular considerations
Mismatch repair status is relevant across several sites in this group. Site-specific markers include RAS and BRAF in colorectal cancer, HER2 in gastric and oesophageal adenocarcinoma, and FGFR2 and IDH1 in biliary tract cancer.
Markers commonly discussed in gastrointestinal & hepatobiliary cancer
- MMR / MSI
- HER2
- KRAS / NRAS / BRAF
- FGFR2
- IDH1
- NTRK fusions
- Claudin 18.2
Not exhaustive, and not every marker is assessed in every patient. Which of these is relevant depends on the individual case and should be discussed with the treating team.
Testing
Genomic testing considerations
Site-directed testing, with comprehensive profiling in advanced disease.
Germline
Germline considerations
Lynch syndrome is a recurring consideration across this group; pancreatic cancer raises DNA damage repair gene assessment.
Molecular monitoring
ctDNA and liquid biopsy considerations
Established research interest in colorectal cancer, particularly for molecular residual disease; developing in the other sites.
Single-cell & computation
Single-cell and algorithmic approaches
In gastrointestinal and hepatobiliary disease, single-cell sequencing is used chiefly to characterise the tumour microenvironment and to resolve clonal structure in tumours that are heterogeneous between regions. Single-cell DNA analysis helps establish whether a RAS or driver alteration is clonal or subclonal, which bears directly on how much weight it should carry. Algorithm work here includes molecular residual disease detection from serial samples, mismatch repair classification from sequencing data, and pipelines that reconcile findings across multiple biopsy sites.
Decisions
Treatment decision questions
Questions worth raising with a treating team when a decision is being made:
- Is the primary site precisely established?
- Has mismatch repair status been assessed?
- Has site-appropriate marker testing been performed?
Resistance
Resistance and recurrence questions
- Has the molecular profile been reassessed after progression?
Trials
Clinical trial considerations
Site and biomarker status shape eligibility.
When a precision oncology review may help
A review is most useful where the standard pathway has been exhausted or where the picture is more complicated than a protocol accounts for — rare presentations, treatment resistance, complex or apparently contradictory molecular findings, or a decision between several defensible options.
The output is a structured analysis and a set of questions for the treating team. It is not treatment, and it does not replace the treating oncologist.