Kidney cancer mortality in Spain: geographic patterns and possible hypotheses.
BACKGROUND
Since the second half of the 1990s, kidney cancer mortality has tended to stabilize and decline in many European countries, due to the decrease in the prevalence of smokers. Nevertheless, incidence of kidney cancer is rising across the sexes in some of these countries, a trend which may possibly reflect the fact that improvements in diagnostic techniques are being outweighed by the increased prevalence of some of this tumor's risk factors. This study sought to: examine the geographic pattern of kidney cancer mortality in Spain; suggest possible hypotheses that would help explain these patterns; and enhance existing knowledge about the large proportion of kidney tumors whose cause remains unknown.


METHODS
Smoothed municipal relative risks (RRs) for kidney cancer mortality were calculated in men and women, using the conditional autoregressive model proposed by Besag, York and Molliè. Maps were plotted depicting smoothed relative risk estimates, and the distribution of the posterior probability of RR>1 by sex.


RESULTS
Municipal maps displayed a marked geographic pattern, with excess mortality in both sexes, mainly in towns along the Bay of Biscay, including areas of Asturias, the Basque Country and, to a lesser extent, Cantabria. Among women, the geographic pattern was strikingly singular, not in evidence for any other tumors, and marked by excess risk in towns situated in the Salamanca area and Extremaduran Autonomous Region. This difference would lead one to postulate the existence of different exposures of environmental origin in the various regions.


CONCLUSIONS
The reasons for this pattern of distribution are not clear, and it would thus be of interest if the effect of industrial emissions on this disease could be studied. The excess mortality observed among women in towns situated in areas with a high degree of natural radiation could reflect the influence of exposures which derive from the geologic composition of the terrain and then become manifest through the agency of drinking water.
Cancer and Environmental Epidemiology Area, National Centre for Epidemiology, Carlos III Institute of Health, Madrid, Spain. glabente@isciii.es
Gonzalo
G
López-Abente
Nuria
N
Aragonés
Beatriz
B
Pérez-Gómez
Rebeca
R
Ramis
Enrique
E
Vidal
Javier
J
García-Pérez
Pablo
P
Fernández-Navarro
Marina
M
Pollán
D001417:Background Radiation; D005260:Female; D006801:Humans; D007220:Industrial Waste; D007680:Kidney Neoplasms / Q000453:epidemiology / Q000401:mortality*; D016015:Logistic Models; D008297:Male; D012307:Risk Factors; D017678:Sex Distribution; D013030:Spain / Q000453:epidemiology
D007220:Industrial Waste