In his new novelisation of Doctor Who's 50th anniversary special 'The Day of the Doctor', Steven Moffat reveals that the films exist in the Whoniverse as actual movies, with Cushing starring in big-screen adventures adapted from the Doctor's "real" exploits.
"Seen them? [The Doctor] loves them," UNIT's Kate Stewart tells Clara in a specially-written scene. "He loaned Peter Cushing a waistcoat for the second one, they were great friends."
http://www.digitalspy.com/tv/doctor-who/news/a854099/doctor-who-target-day-of-the-doctor-peter-cushing/