[en] In the framework of multiple scattering theory the expressions are obtained for the maen number of inelastic collisions of leading hadron and the mean multiplicaty of shower particles in proton-nucleus interactions with consideration of the leading hadron type change (transfer of leading property from a nucleon to a pion). The comparison of calculations with experimental data shows that the multiplicity excess of shower particles in nucleon-nucleus collisions as compared with the nucleon-nucleon ones cannot be entirely due to multiple inelastic interactions of the incident nucleon only but is apparently also due to inelastic interactions of secondary particles, mainly the leading pion collisions