Ooo choc! Handy!
For those of a technical nature, the Lancet has just produced www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)62422-8/fulltext?elsca1=ETOC-LANCET&elsca2=email&elsca3=E24A35F which is the most mind-boggling thing to read. I'm going to have a go at explaining this. Feel free to totally ignore the explanation if it makes you go cross-eyed. I'm not a statistician so if there are some out there who think this explanation is wrong, do say.
But...in basic terms, some people get chemo before surgery. (Neoadjuvant chemotherapy)
That's so the team can see if the chemo shrinks the lumps and gets rid of it from lymph nodes etc.
If it goes completely, it's called a "pathological complete response" (pCR). This is good.
How good? This study looked at 12000 people. But what follows is all about statistics, not actual real people.
They found that if you took a random 100 people who we guess were ALREADY in the 'unlucky group who are going to have an oops within five years judging from their results' ...any who then got a pCR (no cancer at all after chemotherapy) only had a 44% chance of an 'oops' within five years. Hazard Ratio 0.44. They would have had a 100% chance of an oops before. So....out of the 100 of them, 66 who were predicted to have it come back are still alive and well.
They found two groups did really well, though; people with Triple Negative and people with ER- HER+ who had Herceptin.
If you take 100 otherwise definitely-going-to-be-unlucky people with Triple Negative, only 24 of the pCR people will have an 'oops'. So out of the 100 of them, 76 are now still fine when they were meant to be definitely back to having cancer again.
If you take 100 otherwise going-to-be-unlucky people with ER- HER2+ and Herceptin, only 15 of the pCR people will have an oops. So 85 of these 'certain to get the cancer again' people out of the 100 haven't had the cancer return.
Remember, this is only looking at the people who were already in the 'unlucky group'. Most people are in the luckier group and were already going to have no cancer returning in the five years.
So having a pCR is very nifty, and especially niftier for anyone with Triple Negative or ER- HER2+ Herceptin.
I think.