G. Saccomanno et al., COMPARISON BETWEEN THE LOCALIZATION OF LUNG-TUMORS IN URANIUM MINERS AND IN NONMINERS FROM 1947 TO 1991, Cancer, 77(7), 1996, pp. 1278-1283
BACKGROUND. Lung cancer was noted to be increased in cigarette smoking
miners and nonminers. Carcinogen particulates deposit differentially
in the central, middle, and peripheral zones of the bronchial tree dep
ending on the size of the particle. The object of this study was to ev
aluate the incidence of tumors; their cell types; and the relationship
of particulate size to their position in the bronchial tree. METHODS.
Tumor position in the bronchial tree was studied for a cohort of 467
uranium miners and 311 nonminers with lung cancer. RESULTS. An examina
tion of all histologic subtypes showed that the proportion of lung can
cers in the central zone was significantly greater in miners than in n
onminers presumably due to the deposition of radon decay products atta
ched to the silica dust particles. The higher percentage of central tu
mors in the miners was primarily due to the distribution of a greater
proportion of squamous cell and small-cell tumors. The ratio of 0.75 f
or the central to middle and peripheral location for adenocarcinomas w
as much lower than for squamous cell and small-cell carcinomas with ra
tios of 1.4 and 7.3, respectively. In the mining cohort, there were te
n times as many small-cell tumors in the central area as in the middle
and peripheral regions, whereas, for the nonminers there were only fi
ve times as many centrally located small-cell tumors as middle and per
ipheral (chi square is 7.0 degrees, P < 0.01). These data suggest that
radon may be deposited preferentially to the central region of the lu
ngs in uranium miners. CONCLUSIONS. Based on our observations of the d
ifferential positions of lung tumors in the bronchial tree for miners
and nonminers and previous studies by others regarding size-dependent
deposition of particulates in the bronchial tree, it is concluded that
inhaled dust, radon, and cigarette smoke combine to form large partic
ulates that deposit in the central bronchial tree. Filtered cigarette
smoke or other small carcinogens form smaller particulates that deposi
t more peripherally. (C) 1995 American Cancer Society.