[Characteristics of lung cancer in patients exposed to silica at work. A comparison of exposed and non-exposed individuals].

BACKGROUND

In 1977 silica was listed as a group 1 carcinogen (demonstrated in humans) by the International Agency for Research on Cancer. However, conflicting results from various studies have kept debate alive as to its carcinogenic capacity. The interest of this debate lies in the large number of workers exposed to silica.

OBJECTIVE

To analyze the differential characteristics of lung cancer among silica exposed and silica non-exposed individuals, to identify indirectly a possible carcinogenic effect of silica.

METHODS

For all males with a diagnosis of lung cancer over a period of 22 consecutive months at the National Silicosis Institute (Oviedo, Spain), we recorded work history, age, smoking habits, spirometry, the presence of pneumoconiosis and histology.

RESULTS

Comparing the results for silica exposed and non-exposed individuals, we found significant differences for age (63.7 8.8 and 66.7 8.6 y, respectively; p < 0.05), smoking (44.1 22.4 and 48.9 22.3 packs/year; p < 0.05) and a Tiffeneau index under 70% (in 78% of exposed vs. 55% of non-exposed patients; p < 0.05). No significant differences in histology, signs and symptoms or radiographs were observed between the two groups. In the multifactorial analysis in function of age of onset, exposure to silica continued to be an independent predictor.

CONCLUSIONS

Our results show that the clinical and radiological signs and histology of patients exposed or non-exposed to silica did not differ. However, lung cancer appears earlier among individuals with work-related exposure to silica and lower rates of tobacco smoking, suggesting some carcinogenic effect for silica.