Incidence of Death from Tumours of the Urinary Bladder

The investigation of possible environmental risks that may lead to an increase in the frequency of the occurrence of tumours of the urinary bladder requires a measure of the frequency with which the condition will be expected to occur in a sample of the population not regarded as being subjected to any known environmental hazard. For practical purposes, since no such population can be enu merated and defined, it is proposed to regard the total male population of England and Wales as representing such a sample. If the frequency of the disease shows any marked tendency to age specificity, and if other influences at present not elucidated which vary at different dates produce a marked effect, then this measure must take into account both the age composition of the population under consideration, and the varying effect of contemporaneous conditions. At present, English morbidity statistics have not reached a sufficiently high degree of excellence to allow a reliable estimate of this kind to be formed from them. However, the mortality statistics are of sufficient quality, and especially so in the case of bladder where all certificates showing mention of bladder tumour, classified into cancer or tumours, benign and unspecified, have been collected separately at the General Register Office since 1921. This separation applies to males only, but since the immediate programme of investigation of risk is confined to predominantly male occupa tions, this limitation is at present immaterial. Moreover, this separation into certificates men tioning tumour of the bladder overcomes the technical difficulties introduced by the change of certificate classification introduced in 1940 (Registrar General, 1949), if we adopt the convention of speaking of death certification rate instead of death rate.