I wrote this at home over the weekend with nothing but brief press reports to go on. Now that I have been able to see the summary report in Lancet Oncology my views have changed somewhat, but I decided to put this on the blog anyway. More comment to follow.
I heard an all too brief radio interview with Valerie Beral on the day that it was announced that Oxford medical statisticians had found a link between cancer (of all forms) & height.
Now this is an association which must be regarded with a great deal of caution; height is in turn correlated with many other factors (genes, social class & nutrition) which could make the link only, at best, indirectly a causal one. There is also the fact of secular trend – height, affluence, cancer, longevity, educational levels & many, many others all rising together across time.
One intriguing speculation about how this might be a causal relationship is the idea that taller people simply have more cells & thus more chances for a cancer to develop. In this respect I am intrigued by the fact that the relationship between height & cancer risk has a square in it – risk increases by 16% for every 4 inches of height. As Quetelet observed, weight tends to increase according to the square of the height – the body can be regarded as an idealised cylinder – implying that height does indeed increase the number of cells by more than a simple proportion – but apparently nobody knows if this is true. Against this one might argue that not all organs show the same proportionate increase in volume in relationship to height; in particular the most recent gains in height may come mainly from an increase in leg length, which would mean a proportionately smaller increase in the number & types of cells involved in a taller human body.
The idea that more cells lead to an increased cancer risk is however particularly interesting in relation to breast cancer. There has been an undoubted increase in the size of breasts, along with some evidence that this starts at an earlier age, earlier than can be accounted for by a reduction in the age of menarche; it may also affect boys as well as girls. Increasing breast size is also not simply related to obesity – a recent article in The Times discussed the problem of finding suitable bras for otherwise slender teenage daughters with narrow backs. The role of oestrogens in the development of breast cancer is at least partially understood, & oestrogens (including phyto-oestrogens) have also been implicated in various male ills; perhaps hormones, in particular steroid hormones, play an even wider role in cancer, perhaps encouraged by changes in nutrition, & Einstein was right to say that our destiny lies in our endocrine glands.
The other complicating factors in this relationship with height are social class & education. Social class (in this country at least) is correlated positively with height & inversely with mortality. Of course the obverse of this is that height is positively correlated with longevity; cancer risk increases with age, so the higher up the social scale you are the more likely you are to live long enough to develop cancer. Set against this is the puzzle that cause of death becomes more miscellaneous in the oldest age groups.
Personally I remain sceptical about the idea that height can be in any sense a cause of cancer – it does not chime with my lived experience, but then I have spent most of my life being taller than most people I know, so those who have died of cancer have been shorter than me. In fact I have always had a sneaking (illogical) suspicion that height may, in one sense, provide me with a degree of protection against lung cancer at least. This is because, relatively speaking, my extra inches lie between my shoulder & waist; this means that I have long lungs (as is testified by the fact that I have twice had the experience of a radiologist having to retake a chest x-ray: “Terribly sorry – I missed a bit”
In any case there is nothing I or anyone else could sensibly do to reduce my height. I still feel the horror of my reaction to an article published in a popular women’s magazine when I was a teenager about a Dutch girl who had endured surgery to remove inches of bone from her legs – I think she was only 6’ 4” tall. And as recently as the 1970s, even perhaps the 1980s, there were papers in medical journals on the efficacy of oestrogen injections at a critical point in puberty to stop a girl from growing too tall.
On the other hand perhaps this news will make it unethical to give growth hormones to boys who otherwise will lack the inches considered to be so important for success in the world as a man.
Perhaps I should just put my faith in osteoporosis to save me from cancer.
