How long ago was the Trademark published? Those that have existed for a long time have much more strength. Otherwise, its about likelyhood of consumer confusion. On its face it doesn't seem that there would be much but you also haven't given us any details on what your book is about or what the title is. In addition, even if unrelated that doesn't mean they can't file an action against you. Even if they lose it is still going to cost you time and money. What is stopping you from changing the title?

