Medical charities and prevention SIR,-I am surprised at the outburst from the medical charities (19 January, p 178, and 26 January, p 249) on your recent leading article on medical charities and prevention (22-29 December, p 1610). They make so many points (excuses?) that I am reminded of the saying "The best way of hiding a leaf is in a forest."Both cancer and heart disease have a common connective factor, that of smoking. But one charity says that "the means of changing people's social habits have yet to be devised ... and further research is needed into preventive education before large sums are committed to propaganda." Yet we know 250/ of cancers could be prevented if we could stop the smoking epidemic.If the charities are worred about the public and their need to be accountable to it, then I as a member of the public-a concerned general practitioner and one who donates to these charities-will be looking for more effect in the preventive field before I next contribute.