Vilen Prokofyev was born on April 22, 2001, in Satpayev, Kazakhstan, where he started playing for the local Kazakhmys. In 2013 he moved to the Barys junior hockey system. The first symptoms appeared in May 2019, when the netminder began having problems with his hip. After examinations and tests, Vilen was diagnosed with Ewing's sarcoma, a rare form of cancer, and one of the most aggressive malignant tumors.
Vilen underwent specialized treatment in Moscow, while KHL and JHL clubs held charity events raising funds for his cure.
The Kontinental Hockey League expresses its sincere condolences to the family, relatives, and friends of Vilen Prokofyev.