Pavlos Ioannou performed an innovative surgical operation for breast cancer in Vienna University Hospital in 1861. A few years later, after his return to Greece, an operation performed on his closest friend's child, which led to fatal complications, led him to retire from surgical practice. William Halsted travelled to Europe in order to master European surgery, including at Vienna University, and about 20 years later he published his famous method for radical mastectomy, which appears to be identical to Ioannou's operation. This article debates whether Halsted studied Ioannou's method in the archives of Vienna University (and was encouraged by Ioannou's retirement to develop this technique), whether he learned about it through his peers, or whether this was simply a historical coincidence.
Keywords: Pavlos Ioannou; Vienna; William Stewart Halsted; breast cancer surgery; radical mastectomy.