Just as he did last year, actor Matt Damon will join Mass. General Hospital’s Cancer Center in celebrating “The One Hundred,” a fund-raiser honoring 100 people, institutions, or groups that have helped advance the fight against cancer. The event is June 7 at the Westin Boston Waterfront. The cause is near and dear to Damon, whose dad, Kent, has been treated by Mass. General doctors in recent years for multiple myeloma.