Occupational cancer

Occupational exposures are important contributors to the total burden of cancer in the United States. No histologic features distinguish occupational cancer from that due to other causes. The IARC provides a systematic framework for evaluating the evidence linking occupational exposures to human cancer and publishes summary monographs which detail the strength of evidence for approximately 732 agents evaluated to date. These monographs are one of the most reliable reference sources for practitioners who must answer questions regarding cancer risk to working populations. The diagnosis of occupational cancer must be based on a systematic approach in which the diagnosis of cancer is confirmed, the exposures of the patient are defined and quantified, and the scientific evidence regarding the risk from such exposures is evaluated. Cancer screening programs in work settings are difficult to justify based on scientific principles and must be adapted to the circumstances of exposure and to meet legal requirements for medical surveillance, if they are to be performed at all. Investigation of cancer clusters often presents a difficult scientific challenge, which requires careful case ascertainment, calculations of risk based on an appropriate reference population, identification of distant past exposures, and a search for common elements among the cases. Negative and equivocal findings are common, and it is important for investigators to be able to demonstrate the scientific rigor of their approach in resolving these issues.