Unless you've committed to OB/GYN in your personal statement, you could wiggle out with something along the lines of it being a serious ethical, moral, political, emotional issue but one that you have not considered from the viewpoint of a physician because you do not intend to practice within a specialty that has abortion within its scope of practice. Then, to show that you aren't going to completely wuss out, you say, "however, I have given significant thought to the issue of physician assisted suicide and I believe that I would...."
Of course, if you think that your future lies in radiology, derm, pathology, or occupational medicine (to name a few) physician assisted suicide is a moot point and you'd have to come up with some other hot button issue like care for the uninsured.