Dr. Atul Gawande, author of the bestselling “Being Mortal” and a surgeon at Brigham and Women’s Hospital, was the featured speaker at the sold-out Good Shepherd Institute Dinner, a benefit for the Newton-based agency devoted to end-of-life education, training, and research. . . . Former “American Idol” judge Kara DioGuardi performed for guests at “UnMask Cancer” at District Hall the other night. The event was a benefit for adult and pediatric cancer care and research at Dana-Farber Cancer Institute.