My mother got diagnosed with stage 3 breast cancer a couple months ago. Though it's a huge deal to my family and to me and it's an issue that's been at the forefront of my mind every single day, I made a conscious decision to refrain ever posting any public status updates on Facebook about it. I think it's just tacky. Sure, I've e-mailed people I'm close to and asked them to pray but they are people I know who are naturally concerned in some way.
Maybe it's just a personal style sort of thing, but I have seen way too many of my other friends on FB carry the hourly status updates about sick relatives to the point of it being self-serving and narcissistic. I choose not to take that route. It's my mom's struggle and I'm not going to ask people to PLZ PAY ATTN 2 MEEE!!! because I have a sick mamma.