Phillip Kendall’s answer is the correct, here is why.
Unfortunately you have a tricky trade-off. On one hand, you are not required to explain anything and the company can't really ask (in the US). On the other hand the company is not required to hire you and if there is anything in your resume or the interview they don't like, they will just move on to the next candidate.
So you need to decide what level of disclosure you are comfortable with and you can practice what you will say if the questions are getting past your comfort zone.
In the US a good phrasing on your resume would be "Medical Leave of Absence, fully cleared to return to work, no future accommodations required or expected".
These are legally well defined terms that say the following:
- You had a medical issue as certified by a physician
- A physician has also certified that you are "cured" and are able to return to work
- Your medical condition has no further impact on your ability to work, you can be treated as any other "healthy" employee.
If they still ask for more details, it's really up to you. There is nothing wrong with "I prefer not to discuss this as it's personal. If there are specific concerns or considerations about the current role, I'm more than happy to address them directly".
That sentence redirects the inquiry to the potential impact of your health on your expected job performance. This could be questions like "can you lift stuff", "are you ok with pulling the occasional all-nighter if a project is on fire", "do you need frequent breaks and/or limit on work times", etc.
These are GOOD questions and you should encourage or bring them up proactively. Every interviewer will THINK these questions. If they can't ask, they will just guess and make up their own answer. It's much better if you actually get them out in the open and answer them truthfully.