# Individual patient data meta-analysis of microsatellite instability as a biomarker in gastric cancer (MAGIC, CLASSIC, ARTIST, ITACA-S)

Source: https://onco.cc/key-papers/paper-pietrantonio-msi-gastric-meta-analysis-jco-2019/  
OnCo record `paper-pietrantonio-msi-gastric-meta-analysis-jco-2019` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Pooling four trials showed that microsatellite-unstable gastric cancers have a much better prognosis after surgery and gain nothing from perioperative or adjuvant chemotherapy, which may even harm them.

## Summary

Individual patient data meta-analysis of 1,556 patients from four randomised trials of resectable gastric cancer (MAGIC, CLASSIC, ARTIST, ITACA-S), of whom 7.8 percent had microsatellite instability-high tumours.

Five-year disease-free survival was 71.8 versus 52.3 percent and overall survival 77.5 versus 59.3 percent for microsatellite-unstable versus stable tumours; chemotherapy improved survival in stable tumours (hazard ratio 0.65) but not in unstable ones (hazard ratio 1.03), with a suggestion of harm.

## Fields

- Kind: Key paper
- Last checked: 2026-09-17
- Journal: Journal of Clinical Oncology
- Year: 2019
- DOI: 10.1200/JCO.19.01124
- Authors: Pietrantonio F, Miceli R, Raimondi A, et al.
- Findings: Five-year overall survival 77.5 percent (unstable) vs 59.3 percent (stable) with surgery alone.; Chemotherapy hazard ratio 1.03 in microsatellite-unstable tumours vs 0.65 in stable.
- What it means: Microsatellite instability testing is recommended before perioperative chemotherapy for gastric cancer, and immunotherapy-based trials are the preferred approach for unstable tumours.
- Caveats: Small number of microsatellite-unstable patients (121); confidence intervals were wide.

## Sources

- J Clin Oncol 2019: https://doi.org/10.1200/JCO.19.01124
- PubMed: https://pubmed.ncbi.nlm.nih.gov/31513484/

## Connected records

- cancers: [Microsatellite-unstable (MSI-high) gastric cancer](https://onco.cc/cancers/gastric-msi-high/)
- journals: [Journal of Clinical Oncology](https://onco.cc/journals/jco/)

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