In May 2016, Russ took a routine anti-doping test which showed high levels of the hormone human chorionic gonadotropin (hCG), which can be produced either by anabolic steroids or cancer. After consulting a doctor on the 18th, it was confirmed that he had a malignant tumour. However, he put himself forward to play their promotion/relegation play-off against 1. FC Nürnberg the following day. In the match, he scored an own goal from Sebastian Kerk's free kick in a 1–1 home draw; Frankfurt stayed up 2–1 on aggregate with Russ absent from the second leg.