Yew trees don't just turn into monsters (although it's a handy trick); they also give us the chemotherapy drug Taxol, which Siobhan Dowd herself took. (Source.)
When Conor mentions the tube going into his mom's chest, he's talking about a catheter through which the chemo gets pumped directly into her bloodstream. It's not pretty, but if you're one of those people who watches gruesome surgery shows, here's how it works. (Fair warning: that video is not for the faint of heart.)
Patrick Ness doesn't just write awesome children's books; he also throws down a few 140-character pieces a day. We're talking about his twitter, of course. And he even answers readers, so get those lightning-fast typing fingers ready.