Occupation as a risk factor for oral and pharyngeal cancer
Abstract Introduction and objectives Oral and pharyngeal cancers represent the fifth most common cancer type and the seventh cause of deaths by cancer worldwide. Few studies have assessed the risks associated with occupational exposure and in many cases the results are contradictory. The objective of this study is to determine the association between occupational exposure to carcinogenic substances and risk of oral and pharyngeal cancer (including nasopharynx and hypopharynx) through a systematic review. Material and methods A literature search was carried out in MEDLINE (PubMed) and EMBASE. The articles were selected by two independent investigators on the basis of inclusion and exclusion criteria (sample size, publication type, etc.). Results Ten original articles were included, all with a case-control design. The results showed that a prolonged exposure to formaldehyde may increase the risk of nasopharyngeal and hypopharyngeal cancer, whilst other chemical products were not associated with these tumours. The exposure to different types of particles (such as wood dust in nasopharyngeal cancer) and smoke of various origins has also been associated with several oral and pharyngeal tumours. Conclusions The literature reviewed shows that occupational exposure to formaldehyde may be associated with an increased risk of nasopharyngeal and hypopharyngeal cancer. The results regarding other occupational exposures are not consistent, therefore additional studies with more statistical power and better design are needed to ascertain if occupation is really a relevant risk factor for these types of cancer.