Applicant2002,
I'll clarify something first. An overseas assignment is not the same thing as a deployment. If you get an assignment to someplace like Germany, Italy, Japan, or England, where the military has fixed, long-term facilities, you live and work in that country much like you would if you're stationed in the US. You commute to work in the morning and go home to your family at night. Although every overseas base has its own rules, you might not even have to live on post.
A deployment is different. First of all, overseas assignments generally last 3 years, whereas deployments rarely last longer than six months. The idea is that you are "deployed from" somewhere- ie, away from your normal duty station, your home and family. Except for training deployments, which rarely last much longer than one month, most deployments are to relatively hazardous areas where something could flare up at any momment (Bosnia, Kosovo, Afghanistan, Kuwait, etc). You live on a base (or ship) and you tend to stay there, in uniform, unless the mission requires you to leave the base. Its military life 24-7, as opposed to 9-5, five days a week.
Now, back to the original question about are their any specialties that tend to get deployed less. Although it varies, in general, critical care specialties tend to spend less time deployed. I can't imagine much use for an oncologist on a deployment. Primary care gets deployed much more often. You'll also find most surgical specialties on deployments. However, just about any military specialty that you find in the US you can find in a military hospital in Germany, Japan or Korea. I hope this has been helpful.
