Awful news ... WWE legend "Hacksaw" Jim Duggan says his cancer has returned -- and both he and his family are "terrified."
The wrestler did add, though, his doctors are "very optimistic that they caught it early."
Duggan had battled the disease for most of 2021 ... needing multiple procedures -- including one in which doctors removed his prostate -- to try to eradicate it. In December, he said medical experts had declared him officially cancer-free.
CANCER-FREE FOR CHRISTMAS
But, the 68-year-old said in a video message on Sunday that it had returned .