It depends on your relationships and what you want to tell. My Mum decided it was her place to tell all my immediate family, even though I'd asked her not to.
I run a health & fitness facebook group, so when I had to go into hospital for the op I posted a pic of me jumping on my bed in my pj's (with the obligatory teddy bear) and let them all know, they were incredibly supportive but didn't push for information.
One of my Aunts was diagnosed with lung cancer the same week as I found out I had cancer. So all my Aunts and Uncles got regular letters in the mail telling them how I was going and what was happening. I didn't go into the gory itty bitty stuff, but just kept them in the loop so they didn't worry.
