Hi joshhollowayspieceofass.
Hope your friend and her DS are coping okay, and als hope you are too as you're obviously going to take some of this stress and worry on being her friend.
As other shave said, childhood cancers are highly treatable these days and things which would have been fatal 10-20 years ago seem to have 80% or better rate of cure / survival (which means at 5 years after end of treatment, the child has survived after the initial treatment).
Children do very well regardless and almost despite of what is going on around them. It sounds really trite to say that at least yr friend's DS is so young - things like taking blood pressure, temperature etc may / tend to be easier than in an older child. My DS is 3 and has cancer with a 50% cure and the first battle was getting him used to having his blood pressure done which can be quite scary for a little boy who feels fine, but whose mummy and daddy have just been told he only has a 50% chance of making his 9th birthday.
Your friend will be referred / introduced to CLIC Sargent who are an awesome charity which help children with cancer and their families.
There's a great book which Macmillan produce entitled What Can I Do to Help? www.amazon.co.uk/What-Can-Help-Practical-Frontline/dp/1904977391/ref=sr_1_2?ie=UTF8&s=books&q id=1222821096&sr=8-2
Your friend may not know what she needs help with, but from my experience, a cooked homemade dinner which can be put into the freezer is a fantastic thing to do.
One other crucial thing which may help you feel like you're helping your friend and her DS is that from my experience, I could not talk and did not have the energy to speak with every well wisher about my DS and his diagnosis and treatment (and I still can't!) So I kind of nominated little groups where I spoke / texted / emailed one or two people, who then communicated updates to everyone else.
I could go on but two more ways for you to help (when you feel the time is right), offer to drive her to the hospital on the days her DS has day appointments - parking at hospitals is not only expensive but on rainy days like today, it's impossible to find spaces and that adds to the already significant levels of stress and anxiety.
Finally, hug her...alot. She may find some friends and family disappear off the radar - not because they don't care but because they don't know what to say or do, and so it's easier not to do anything at all.
Your friend will meet other parents whose world's have also fallen apart due to their DCs cancer diagnosis and she may find some comfort in their strength.
You obviously care for your dear friend alot..enough to post and ask for fellow MNers for help. And I wish both you and her family well in the coming months and years.