SEX DIFFERENCES IN INCIDENCE OF TUMOURS AT VARIOUS SITES

The frequencies of a number of tumours were compared in males and females after adjustment for the differing age structures of the populations of the two sexes. The data used were: estimates of tumour incidence in the five continents; the mortality experience of England and Wales; tumour incidences in 10 Metropolitan areas of the United States. It was found that, apart from tumours of the reproductive organs which were commoner in women than in men, the ohance of a female developing a tumour was between 40 and 70 per cent of that of a male. Exceptions to this finding were in the cases of tumours of the thyroid and malignant melanoma in which it was suggested that the cyclical endocrine activity of the female might be a contributory factor in the high frequency of these tumours in women and tumours of the lip, larynx, lung and bladder which are relatively more common in men and in which it was suggested that industrial environmental conditions and the habit of cigarette smoking were of aetiological importance. It was suggested that there is a greater immunological potentiality in the female because of her two X chromosomes which are known to carry one at least of the genes concerned with the production of immunoglobulins. Anomalies in the sex distribution of colonic and rectal cancer were noted but were left unsolved. This work was carried out with the aid of a research grant from the Welsh Hospital Board. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.