We have discussed the transition between benign and malignant tumors in relation to mutations, and further mutations in relation to the various forms of adaptations described in pathology

One teacher explains that all human cancers have 5-10 rate limiting mutations which make them malignant. If the cells have fewer mutations than required to be an invasive cancer, they might be hyperplasic, dysplastic, or form a benign tumor. Each of these stages may become malignant. For myeloma and lipoma transition is rare, for polyps in the colon more frequent and for villous adenoma in the colon even more frequent.

Another teacher explains that metaplasia is an adaptative and reversible process where one “well-differentiated” cell type is replaced by another “well-differentiated” cell type from the same germ layer. By well-differentiated “I mean not permanently changed for example by genetic mutations”. Dysplasia occurs after genetic changes including formation and activation of oncogenes or disappearance or inactivation of tumor suppressor genes and is a precursor of malignancy.

Questions:
Do atrophy, hypertrophy, hyperplasia and metaplasia occur without mutations, whereas dysplasia occurs after mutations?

Or may all forms include mutations, but some are arrested in benign reversible forms
whereas others develop more mutations and become malignant:
Mutations occur all the time but fortunately most of them are arrested and deleted – how does this fit with the terms benign and malignant as well as with the definition of reversible/irreversible adaptations?

Added by: Johannes

On: December 26th 2012