Black Sabbath rocker Tony Iommi has revealed the band has organised its reunion tour dates around his six-weekly chemotherapy treatment, because he's too weak to perform for two weeks after the medication.

The guitar great was diagnosed with lymphoma last year (12), and now he faces the prospect of taking chemo drug Rituximab for the foreseeable future.

The medication is one of the four ingredients which makes up the chemotherapy cocktail he took to aggressively attack the cancer, and it leaves him feeling lousy.

He tells Guitar World magazine, "When I'd finished the chemo and the radiotherapy, I went to see the doctor again for my regular blood tests. I said, 'So it's gone now?' And he said, 'No, it's not going to go. You're not going to get rid of it. But we can treat it and work with it.'

"I got all dismal, because I thought it was gone. He said there was a 30 per cent chance of it going away, but I was probably going to have this for life. Now I get treatments to keep it from spreading.

"Every six weeks I go in for an infusion of Rituximab... It takes a few hours, and it makes you feel a bit crap inside and a bit sick. But a couple (of) weeks after, I start perking up again. So that's how we are working it with the shows. I go out, then come back and go into the hospital for more treatment, more blood tests and all the rest of the rubbish. And then we do it all over again."