Sir

In their fascinating Insight Review ”Inflammation and cancer“ (Nature 420, 860–867; 2002), Lisa M. Coussens and Zena Werb traced knowledge of the relationship between inflammation and cancer back to the hypothesis proposed by the German physician Rudolf Virchow: that chronic inflammation caused by certain irritants can lead to cancer. This was later proved correct by two Japanese scientists, Katsusaburo Yamagiwa and Koichi Ichikawa, who showed that repeated painting of coal tar onto rabbits' ears causes carcinomas.

Yamagiwa was delighted with their results and composed a haiku: ”Cancer was produced. Proudly I walk a few steps“. Their paper was originally written in German and published in a journal of the Imperial University of Tokyo in 1915. An English version was published in 1918.

In his Nobel lecture of 1966, Peyton Rous acknowledged the significance of this work. He wrote, ”And then in 1918 came the epoch-making discovery by Yamagiwa and Ichikawa that tarring rabbit skin will cause tumors to arise. This opened an era of rewarding search for other chemical agents — and physical as well — which do the same. It is an era so far from done as to have been the main theme a few months ago of the International Cancer Congress held in Japan; and it was chosen with good reason since some of man's habits, many of the occupations through which he earns his living, and the mischances taking place in his own body can prove fatal through the growths they induce unless something is done to ward them off. All of these oncogens [sic] are initiating in character, and some can be dangerous promoters too, if the exposure to them is long.“