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Endotoxin: does it have a role in prevention of lung cancer
  1. J H Lange
  1. Envirosafe Training and Consultants Inc, P O Box 114022, Pittsburgh, PA 15239, USA

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The paper by Drs Douwes, Pearce and Heederik provides an interesting overview of how endotoxin may interact in atopy and asthma. It discusses issues as to whether endotoxin plays a role in prevention of atopy and asthma or may, in fact, be a contributor to these respiratory diseases. However, readers should be aware that there is another important issue, although controversial, related to endotoxin and the lung—that is, does endotoxin exposure in some occupational groups result in reduced lung cancer rates?

There have been a number of reports2–8 suggesting that endotoxin exposure, mostly in organic dusts, results in reduced lung cancer rates. This reduced lung cancer rate was first identified in textile workers2,3 and later in agricultural4,5 and other groups6,7 exposed to endotoxin. Experimental studies9,10 have supported epidemiological findings and clinical trials11,12 have been undertaken to evaluate this agent and the effectiveness of its immunomediators in cancer treatments. Although the concept of a beneficial effect from occupational exposure is novel,5 it has been reported in at least one other occupational epidemiological investigation of reduced lung cancer rates for a potentially better recognised anticancer agent (selenium).13,14 Most investigators disagree with any benefit from occupational exposure and attribute these findings to various forms of selection bias (healthy worker effect) and lower rates of smokers in study populations (compared with controls).4,5,7

Certainly exposure to organic dusts and endotoxin does not occur without risk. There are numerous reports of the detrimental outcomes associated with such exposures.8 However, when various forms of bias are evaluated, there appears to be in some studies an inability to explain the reduced lung cancer rates.2,4,7

It is encouraged that scientists accept the concept that there is an alternative view for lower lung cancer rates in some study populations. Even though this challenges prevailing thought and conventional thinking, we must remember that tradition dies hard and the birth of a new idea requires a creative and innovative spirit.15


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