Jack Osbourne spent most of his time high on drugs and alcohol while his mother Sharon Osbourne was battling cancer in hospital. In his new book, 21 YEARS GONE, the TV star admits he was too busy taking substances to even visit Sharon, who was diagnosed with cancer of the colon in 2002. Jack writes, "I went straight to Malibu and drowned my fears and my anxieties in a lake full of booze and a cloud of pot. I was so lost in my own self-centredness that I couldn't even muster up the enthusiasm to visit her. "And though it sickens me to admit it to myself now, the truth is that when I did get round to visiting her in hospital, the only emotion I could really feel was boredom. "More often than not though, I didn't even show up. "I was out with my friends getting high. I would pass out at parties and vomit in my sleep. I would drive drunk - even though I didn't have a license. "After months of treatment and waiting, mum got the all clear. The chemotherapy was finished, the cancer seemed to be in remission and I think for the first time she was able to look around her and see what was happening with her family."