Wow, what a bunch of insensitive nincompoops!
Perhaps you should have an educational meeting with some of your friends and/or co workers and educate them in what these medications do to a person. Both my parents battled cancer - my Dad several times with lymphoma and they were exhausted and not themselves for a while. They fought to keep going. I have had a few friends at work diagnosed over the years with various forms of it as well. It sounds like you are a fighter too.
Any way you can just send out a memo ? to your group and perhaps approach it in the way of this- you apologize for not being yourself lately, and just wanted to give them all an update- due to the tumor, the treatment you have undergone has many side effects, and list them!!! Let them know of the limitations you are under. Then let them know you are waiting to hear how new tests come out and if further treatment is needed and then thank them for their support- even if they havent given you any!!
I can almost guarantee that you may either become quite an educator to those who were not aware of things and have more questions to answer, but, it may also stop a lot of the things they are expecting of you that you cannot do right now!!! And MAYBE a couple of them might even feel guilty for being so rude and insensitive!!! Good grief!! At least they may realize what is going on and understand the situation more.
I would just use the blanket 'memo' or note to all your friends with the excuse that you did it that way to avoid having to repeat yourself to so many 'caring friends and aquaintences'!!!!
Hang in there and dont give up!! You are obviously a strong person to be even working like that through this and continuing to go on with your life as normally as you can right now!
Bless you, and you have friends here who will always listen!! Keep your chin up, but remember that some folks, no matter what you try to do, are just not going to get it!