Medical Technology

Omit Periop Chemo for Mismatch Repair Deficient gastric cancer

Patients with mismatch repair deficient gastric cancer had a greater overall survival rates by avoiding chemotherapy perioperatively in a preprint study.

The Most Important Takeaway

  • Median overall survival is better when patients with mismatch repair deficient (MMRd) gastric cancers receive surgery alone instead of surgery plus perioperative fluoropyrimidine/platinum-based chemotherapy.

  • Fluoropyrimidine/platinum-based perioperative chemotherapy can be omitted in patients with MMRd gastric cancer.

Why this is important

  • At present, gastric cancers typically aren’t tested for MMR status except in cases of suspected Lynch syndrome.

  • The MMR status could be used for identifying patients who require perioperative chemotherapy and those who should not.

Study Design

  • Retrospectively, tumor samples taken from 223 patients were examined for MMR status. 23 (or 10.3 percent) were MMRd, and the remaining were MMR-adept.

  • The authors looked into the relationship between MMR status and overall survival.

  • In a meta-analysis authors gathered data from 385 patients in similar studies published up to January 2021.

Key Results

  • Retrospective analysis revealed that patients with MMRd gastric carcinoma who underwent surgery only instead of. those who received perioperative chemotherapy had a better median overall survival rate (HR, 0.67; p =.63).

  • However, MMRp patients had a lower overall survival rate when treated only with surgery (HR, 1.44; P =.36) However, neither of these outcomes was statistically significant.

  • A meta-analysis of data pooled from 385 patients also revealed that surgery alone was associated with improved overall survival among MMRd patients (HR, .36; P= .03) However, surgery alone was associated with lower overall survival in MMRp patients (HR, 1.18; P = .26).


  • Retrospective analysis showed that MMRd tumors were not widespread enough to warrant excluding subgroup analysis.

  • Fluoropyrimidine/platinum-based chemotherapy regimens were heterogeneous.

  • In the meta-analysis, the clinical characteristics of the MMRd and MMRp subgroups were not available.


  • There was no report of study funding.

  • Five authors have reported honoraria and other ties to companies, including Merck Serono, AstraZeneca, BMS, Roche, AbbVie, Novartis, and Medicaroid Europe.

This summary of the preprint study, “Resectable Gastric Cancer: An Observational Study From the German staR Cohort and a Meta-Analysis” is not peer reviewed. The full text is available at

M. Alexander Otto, a physician assistant who holds a master’s degree in medical sciences, is an award-winning journalist who was employed by many major news outlets before joining Medscape. He is a Knight Science Journalism Fellow at the MIT. Email: [email protected].

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