The first gastroscope, an instrument inserted down the esophagus and used to view and detect cancer in the lower esophagus and stomach, was created by Jan Mikulicz-Radecki.1
1Kielan, W. et al. "Jan Mikulicz-Radecki: One of the Creators of World Surgery." Keio Journal of Medicine. 54 (2005): 1-7. [PUBMED]