The Black Sabbath guitarist went public with news of his lymphoma diagnosis last year (12), and the band was forced to scale back on comeback plans. But Iommi refused to stop altogether and recorded the band's new album while undergoing chemotherapy.
Now the frontman, whose wife Sharon Osbourne survived colon cancer in 2002, has heaped praise on Iommi for his brave fight, admitting he knows first-hand the deadly illness is no walk in the park.
He tells New Zealand's Rip It Up magazine, "I was amazed that during his chemotherapy he was still writing songs. My heart goes out to him, because when Sharon had cancer a few years back, she was so sick from chemotherapy she could barely get out of bed.
"It's like having a football kick to the nuts (genitals). The chemotherapy is worse than the cancer. Sharon was having seizures all the time. Tony is doing really well... but he can only go out on the road for six weeks at a time. He has to have infusions or some s**t for his immune system."