I agree people will take their cue from you. I told everyone at work but told almost all of them indirectly, I told my three closest friends and colleagues there and let them--with my clear permission- spread the word to everyone else. I am more comfortable with people knowing, though I wasn't all that confortable doing the telling at first (I've gotten a lot more confortable over time because now I have war stories I can tell).

Problem is when people don't know, you can also get awkward questions, most of which have to be answered by telling them on the spot even when it's not a good time.

"were you in an accident? that looks like a nasty scar"
"why can't you eat (fill in the blank),are you on a diet?"

OR (at least I get this because I was 50 pds overweight when I was diagnosed and have lost over 65 pds since then)) "Wow, you look great, you've lost so much weight. How did you do it?"
(I confess that there's one guy at my workplace who has always been a bit of a woman-ogler who said this to me and I was very tempted to say "cancer" and just walk away and let him sputter but I just said "it's not a good story")

Nelie