INVITED SPEAKERS ABSTRACTS
The term ‘field cancerization’ was first coined by Slaughter et al. in 1953 referring to histologically abnormal epithelium adjacent to tumor tissue within the aerodigestive region and proposed to explain the occurrence of multiple primary tumors as well as locally recurrent cancer out of an ‘ananaplastic tendency involving many cells at once’. This concept describing multiple patches of premalignant disease, a higher than expected prevalence of multiple local second primary tumors and the presence of synchronous distant tumors has been extended to other organs and was meanwhile described in the oropharynx, oesophagus, stomach, lung, colon, anus, cervix, bladder and skin. As with tobacco and alcohol in the case of mucous membranes, the influence of environmental carcinogens involves larger areas of the skin surface leading to simultaneous (usually actinic) damage of a large proportion of epithelial cells, thus contributing to premalignant states within the entire exposed surface. Various molecular techniques have been developed to look for genetic mutations and clonality in areas of field change. Research findings support the carcinogenesis model in which the development of a contiguous genetically altered field with multiple clonally related neoplastic lesions develops. After a genetically altered stem cell forms a clonal unit of daughter cells, these patches might convert into an expanding field in a subsequent critical step after additional modifications and by virtue of its growth advantage. Ultimately, a proliferating field gradually displace the normal epithelium. Eventually, clonal deviation leads to the development of skin cancer within a contiguous field of preneoplastic cells. An important clinical implication is that fields remain after surgery and may give rise to new cancers, designated as second primaries or local recurrences. Expanding preneoplastic fields as crucial steps in epithelial carcinogenesis have important clinical consequences with impact on preventive, diagnostic and therapeutic strategies particularly in the management of non melanoma skin cancers.