Madonna kicks off "Sticky & Sweet" tour

London, Aug 22: Madonna kicks off her "Sticky & Sweet" world tour at Cardiff's Millennium Stadium on Saturday, the latest test of her enduring appeal that comes a week after her 50th birthday. The "queen of pop" will be hoping to eclipse her last trot across the globe in 2006. "Confessions" became the top-grossing tour ever by a female artist with ticket sales of $195 million. "Sticky & Sweet," featuring hits that span nearly 30 years in pop music including her latest album "Hard Candy," includes 49 dates and is due to wrap up in Sao Paulo on December 18. As of Thursday, roughly half the tour venues had yet to sell out including Cardiff, although Live Nation announced in June that the tour was on target to gross more than $250 million. "Sticky & Sweet" is also a major test for Live Nation, the tour company that signed Madonna to a 10-year contract in 2007 reported to be worth a total of $120 million. Record label executives, smarting as some top acts jump ship to sign new deals with the likes of Live Nation and coffee chain Starbucks that reflect changes in the music industry, wonder if companies are paying too much to attract household names.