Am I a jerk for refusing to donate money to AIDS research because various types of cancer are more prolific and can't be prevented?

Yes, I know that AIDS can be contracted through a number of means and some are not preventable. But, by and large, it could be prevented with safer sex measures, clean needles, and education. However, cancer is much more prolific (at least in the United States) and in most cases, can't be prevented. Isn't it only utilitarian and ethical to focus on cancer before we worry about an AIDS cure?