GREY'S ANATOMY - "Stand By Me" - Cristina, unable to concentrate for her first solo surgery, drops a bomb on everyone when she explains that Izzie has cancer and it's bad. Then she's able to operate, on "Grey's Anatomy," THURSDAY, MARCH 19 (9:00-10:02 p.m., ET) on the ABC Television Network. (ABC/CRAIG SJODIN) CHANDRA WILSON, JUSTIN CHAMBERS, SANDRA OH