Cain was placed on the disabled list for the first time in his career last month after he was hit on the right forearm by a line drive off the bat of Pittsburgh's Gaby Sanchez.
In other injury news, Bochy said reliever Jeremy Affeldt will face hitters Tuesday. Affeldt has been out since July 20 with a strained left groin.
Meanwhile, right-hander Chad Gaudin, who is on the DL with carpal tunnel syndrome, will likely throw a bullpen at some point over the weekend.
AJ Cassavell is a reporter for MLB.com. Follow him on Twitter @ajcassavell. This story was not subject to the approval of Major League Baseball or its clubs.