ASCO is May 31 - June 4th this year. And, I'm in full agreement with you. Odds are high they'll present there before publishing. The conferences want unpublished news.
FYI ASCO is May 31-Jun 4, 2013 and abstracts are due Feb 5. Late breaking abstracts are due by Apr 1, but in order to qualify, there can't be any preliminary data available before Feb 5. Timing requirements might not work for Celsion.