IL6R and rheumatoid arthritis: We report a rare case of Stage IVA transverse colon cancer with synchronous liver metastasis that showed complete pathological regression in both sites after discontinuation of tocilizumab, an interleukin-6 receptor inhibitor.<h4>Case presentation</h4>A 79-year-old woman with a history of rheumatoid arthritis and interstitial pneumonia was treated with iguratimod, methotrexate, prednisolone, and tocilizumab.