The Barenaked Ladies' joy over the success of their new album, Stunt, has been tempered by keyboardist Kevin Hearn's battle with leukemia. The multi-instrumentalist has been at home receiving treatments in Toronto since the album came out in early July, but is now feeling well enough to join his bandmates on the road. Last Friday he performed at a Buffalo, N.Y., show where Jason Priestley was shooting the band for a documentary. Then last night he joined BNL onstage at the Palace of Auburn Hills in suburban Detroit, playing guitar, accordion, and keyboards on seven songs, including the hits "One Week," "If I Had $1,000,000," and "Brian Wilson." Hearn looked thin but seemed healthy, and he was particularly animated during "Brian Wilson," leaping and dancing along with frontmen Steven Page and Ed Robertson. The band seemed moved by Hearn's presence; Page beamed and held Hearn's hand as the group returned to the stage for an encore. According to his publicist, Hearn will be performing at Neil Young's Bridge School Benefit this weekend as well. The battle against cancer is one that remains close to singer Ed Robertson's heart. On Thursday, prior to the band's show, he played a concert for just one. She was Alex Graham, 17, who's suffering from bone cancer and has had one leg amputated. Graham met the band when it performed at an in-store last July in suburban Detroit, and again at the MTV Video Music Awards last month in New York. When Robertson heard through family friends that Graham would not be able to attend the Palace show because she was in the hospital receiving chemotherapy, he canceled his afternoon slate of interviews, and instead visited her. Bearing flowers - Robertson had called Graham's father to find out what were her favorites - T-shirts, bumper stickers, posters, and his guitar, Robertson chatted and played a half-dozen songs before heading over to the Palace. "I just thought that was so sweet of him," Graham said. Added her father, "What a mensch. There's not a dry eye on the fourth floor of Beaumont Hospital today."