This paper is the result of an attempt to determine if, in the different social classes obtained by a grading of a large section of the male working population of England and Wales for the triennial period 1910–12, as described by the Registrar-General in the Supplement to his 75th Annual Report, there was shown any special susceptibility to cancer in particular parts of the body. From a comparison of the standardised mortality-rates from cancer in 16 different sites in (1) men of three social grades, namely, the upper and middle classes, skilled workmen and unskilled workmen, (2) two sub-groups of the upper and middle classes and (3) men of two social classes, a higher and a lower intermediate to classes 1 and 3 and 3 and 5 respectively, it seems reasonable to draw the following conclusions:

1. The mortality-rates from cancer in the majority of the parts of the body considered, including amongst others the tongue, oesophagus and stomach, which altogether account for 92 per cent, of the total deaths, are definitely higher in the men of lowest social status; the incidence decreases, though not always regularly, with ascent in the social scale.

2. The mortality from cancer in other parts of the body, namely, the bowel, the prostate and probably the pancreas, is definitely highest, however, in men of the best social status.

3. Though the relatively high cancer mortality-rates in these sites in the best social class may probably be attributed in some measure, which it is difficult or impossible to assess, to improved facilities for, and methods of diagnosis in this class, as compared with those in the lowest classes, this cannot be the whole explanation as the differences are considerable and as no increased mortality from cancer is evident in any of the sites except the pancreas with such an ascent in the social scale as takes place in passing from social group 1 b, to social group 1 a, where the influence of more skilful diagnosis might also be expected to reveal itself. If we may accept the mortality from hepatic cancer in the different social classes as an approximate index of the general accuracy of diagnosis of malignant disease therein, then varying accuracy of diagnosis can have little influence in producing the divergencies in mortality from cancer in these special sites that are found in the social groups under review.

4. The excessive mortality from cancer of the bowel amongst males of the best social class cannot reasonably be ascribed to their habits of life such as high-feeding and easy-living or to their alleged greater liability to autointoxication. If this were so, cancer of the stomach and cancer of the rectum might also be expected to show a higher incidence in the same social class; the mortality-rates from cancer in these sites, however, are not higher in this class than in the lower social classes.