<<....women in less developed countries had very low incidences of breast 
cancer? Surely this is because they have more pregnancies and more 
breastfeeding.>>

That could be one of the hypotheses to test (the pregnancies part, anyway). 
Other suggestions, more or less crazy :-) could include that these women 
don't eat the processed and GM food that western women eat, that they use 
their bodies more, most likely that they die from other causes before they 
get to the breast cancer stage.  Who knows, perhaps sitting watching TV or 
walking through shopping malls causes breast cancer.

Causality has to be carefully tested (remember the recent "research finding" 
that ran something like *people who had lots of ear infections as children 
were more likely to end up with diabetes*).  There have been six recent 
articles on statistics on the BBC. 
http://news.bbc.co.uk/2/hi/uk_news/magazine/7605118.stm   See particularly 
Lesson 5: Causality http://news.bbc.co.uk/1/hi/magazine/7592579.stm

I don't mean to be flippant - I DO believe that not-breastfeeding is 
associated with higher incidences of cancers.  I have a hard time, though, 
believing that more-than-a-few pregnancies can improve a woman's health. 
Would be interested to hear of research otherwise.

Best wishes
Jacquie Nutt IBCLC 

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