Excess of other cancers in WalesBMJ 1994; 308 doi: https://doi.org/10.1136/bmj.308.6923.268a (Published 22 January 1994) Cite this as: BMJ 1994;308:268
EDITOR, - As Cleone Rooney and colleagues have shown an increased risk of prostatic cancer in men exposed to certain internally incorporated nuclides, including strontium-90, caesium-137, and caesium-134,1 increased incidence of the disease might be expected in those countries that experienced fallout of fission products from atmospheric testing. One place where such a comparison can be made is Wales: contamination related to rainfall in Wales was more than twice that in England in 1958-65.2
The figure compares standardised registration ratios for prostatic cancer obtained from the Office of Population Censuses and Surveys and Welsh cancer registries based on the combined rates for 1979. There is a clear increase in the differential and total incidence of the disease in line with the differences in contamination 20 years earlier.3
Rooney and colleagues' study may be pivotal in highlighting the fact that certain internally decaying nuclides may enhance the risk. The increase in prostatic cancer in Wales is only one aspect of a general and unexplained increase in cancer in Wales between 1975 and 1987 (the last year for which data are available).
One illuminating example is the incidence of bone cancer (International Classification of Diseases (ninth revision) code 170). This remained the same in the two countries between 1962 and 1975, when it began to increase in Wales. In 1984 the incidence in Wales peaked at 350% of that in England, which remained constant at about 1/100000.3 Though the American Committee on the Biological Effects of lonizing Radiations does not accept that the prostate is radiosensitive and might have difficulty in accommodating the findings of Rooney and colleagues, it accepts a causal link between 90Sr and bone cancer, though not at the low doses involved reported by Rooney and colleagues.4 With the help of the British National Radiological Protection Board, and using published data on intake of 90Sr,2 Green Audit (Wales) has calculated that the 10 year dose to the bone surfaces of people in Wales during 1958-65 was 0.75 mSv.
On the basis of the currently accepted risk factors for radiogenic bone cancer.4 the predicted number of fatal cancers resulting from this dose in the population of Wales (three million) is less than 1.5 for all time. If it is assumed that the excess incidence is equal to the incidence in Wales minus that in England for each year, then that yields some 425 excess bone cancers in Wales for the period 1979-87. If these cancers were caused by 90Sr then there must be an error in the perception of this hazard of some 500 times.5 A similar enhancement of effect is needed to explain Rooney and colleagues' findings.
Algorithms of risk derive mainly from data on short term external irradiation.4 In the Hiroshima series, irradiated and control groups were both exposed to equal internal contamination and hazards from this source would have been missed.
Comparison of rates of cancer in Wales and England since the 1960s raises important questions about the radiation from internal isotopes, and such questions must surely also follow Rooney and colleagues' work.
I thank John Harrison of the National Radiological Protection Board for help with calculations of doses and risks.