Association between microsatellite instability and tumor response to neoadjuvant chemoradiotherapy for rectal cancer

Soo Young Lee, Duck Woo Kim, Jaram Lee, Hyeong Min Park, Chang Hyun Kim, Kyung Hwa Lee, Heung Kwon Oh, Sung Bum Kang, Hyeong Rok Kim

Research output: Contribution to journalArticlepeer-review


Purpose: The relationship between microsatellite instability (MSI) and tumor response after neoadjuvant chemoradiotherapy (nCRT) in rectal cancer remains unclear. The present study aimed to evaluate the association between MSI and tumor response to nCRT in rectal cancer treatment. Methods: Patients with rectal cancer from 2 tertiary hospitals who underwent nCRT, followed by radical surgery, were included. The microsatellite status was determined using a PCR-based Bethesda panel. Tumors with a Dworak's tumor regression grade of 3 or 4 were considered to have a good response. Predictive factors for a good response to nCRT were analyzed. Results: Of the 1,401 patients included, 910 (65.0%) had MSI results and 1.5% (14 of 910) showed MSI-H. Among all the patients, 519 (37.0%) showed a good response to nCRT. A univariate analysis showed that MSI-H tended to be negatively associated with a good response to nCRT, but no statistical significance was observed (7.1% vs. 24.1%, P = 0.208). Multivariate analysis showed that well-differentiated tumors were the only predictive factor for good response to nCRT (odds ratio [OR], 2.241; 95% confidence interval [CI], 1.492-3.364; P < 0.001). MSI status tended to be associated with the response to nCRT (OR, 0.215; 95% CI, 0.027-1.681; P = 0.143). Conclusion: MSI-H was not associated with response to nCRT in patients with rectal cancer.

Original languageEnglish
Pages (from-to)176-182
Number of pages7
JournalAnnals of Surgical Treatment and Research
Issue number3
StatePublished - Sep 2022
Externally publishedYes


  • Chemoradiotherapy
  • Microsatellite instability
  • Rectal neoplasms


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