As discussed in an earlier blog, precancers, despite their importance, have not been the subject of much research. We still are confused about some of the most fundamental properties of the precancers.
For example, is each cancer preceded by a precancer that is unique for the cancer? Or may one precancer precede many different cancers?
My own opinion is that there are instances where a single precancer can lead to any one of several different cancers.
The instance that comes to mind is bronchial squamous metaplasia with dysplasia. This precancer seems to precede the three common cancers than arise from the bronchus: squamous carcinoma, adenocarcinoma of bronchus and small cell carcinoma.
This should come as no surprise as adenocarcinomas of lung, that may appear monomorphic on light microscopy, often have tripartite differentiation (squamous, glandular and neuro-endocrine) on electron micrographic examination. Likewise, dysplastic squamous metaplasia often consists of a mixture of these three cell types. How one cell type is selected to dominate in the resulting tumor may just be a function of chance, as dysplastic subclones -- with genetic alterations that confer growth advantage -- are selected over time.
- Copyright (C) 2008 Jules J. Berman
key words: lung cancer, preneoplasia, premalignant, preneoplastic, incipient neoplasia, pre-cancer, dysplasia, metaplasia, intraepithelial neoplasia