I don't live in a small town, but I had the same concerns.
The only folks who really knew where my boss, wife and kids. In work, I only told folks that I was going to be on medical leave. Outside of work, if anyone specifically questioned what was wrong, they I told them (think I only told 3 folks).
Since my medical leave was really about
CANCER, I think folks generally focus on the disease - not the side effects.
I will be going back to work in two weeks, at that time, I will have no hesitations in anyone that I beat the "Big C". If fact, I will proudly say that I beat it and will stress to others the importance of early detection.
If anyone brings up the side effects, I'll just tell them that they are just short term (no one has to know how long "short term" really is).
You got to put a "positive" spin on it.