Cain departed in the fourth inning of a 10-5 loss to the Pirates on Thursday. X-rays on Cain's bruised forearm were negative.
He was hit when Sanchez led off the fourth with a groundout. Trainer Dave Groeschner and manager Bruce Bochy hustled out to check on the pitcher, who walked off the mound on his own moments later.
Cain allowed three runs and seven hits in 3 1-3 innings. With the Giants out of the playoff race, there will be no reason to rush Cain, who is 8-8 with a 4.43 ERA this season in 26 starts over 156 1/3 innings.