OK - here's my perspective, having been through chemo and lost my hair.
It makes me uncomfortable - while I appreciate people do it with the best intentions.
Shaving your head is NOT like losing your hair to chemo. In no way.
When you lose your hair to chemo, you have no choice, it's not just the loss of hair, it's the loss of control, the loss of confidence in your body, when your hair eventually grows back, it is not the same - it looks different and feels different.
Losing you hair to cancer treatment hurts - your head hurts where the hair has come out.
If people are going to shave their heads in sympathy the also need to shave their eyebrows, pluck out their lashes, shave all their body hair off, and then somehow make their skin go all papery and weird. Add in runny eyes, nose bleeds (oh yes - pluck out your nose hair too) endless diarrhoea and feeling like you've been hit by a truck for months on end.
And the knowledge that you may die of the treatment rather than the illness.
I could go on but you get my gist.
losing your head hair is the most visible sign of chemo (although not all chemo makes you lose your hair) but it's not the worse side effect of cancer treatment (in a choice between horrid stuff and horrider stuff)
I think cancer patients sometimes get irritated by this kind of thing because it somehow dismisses your experience. Cancer isn't a chance to try out a new hair do and wear some snazzy hats, and to reduce it to that is insulting. It is a physically nasty and mentally devastating and frightening disease, you are never the same afterwards. It truly sucks. And it kills people.
Give your hair to Little Princesses for wigs - that's a good thing, but just do it, don't broadcast it, don't say 'look at me. I've shaved my head, now I know what it's like to have cancer' No you don't. You really really don't.
I don't want to sound self pitying, I'm not - I am well for now and very lucky, but I have lost some truly wonderful friends to this illness. Most of the people who have had cancer that I talk to about this kind of sponsorship are uncomfortable with it, we just want a bit of real discussion and understanding about what chemo and cancer means to patients and families.
Cancer treatment is much more than chemo and hair loss - it's rads and surgery, sometimes multiple surgeries, and loads of other things. That's good - anything we can throw at this illness is good. But none of them are fun
So shaving your head? - No, not from my point of view.
It doesn't increase awareness of the many illnesses that make up cancer, it just increases awareness of the person doing it, and brings them a lot of 'your so brave' remarks. Most cancer patients I know hate being told they are brave - it's more a case of trying to deal with the shit life has thrown at you - there's no choice in it.