D. Harvatis Jul 13, 2015:

I wouldn't ask you to change your opinion, I'm just trying to help the asker by questioning its basis.

Peter Close Jul 13, 2015:

To D. Harvatis I think that at least the first reference I gave mentions the relevance of genetic lineage in grading or categorising tumors, but I admit that I have not read the whole article yet. However, your comment does not alter the fact that I agree with Ourania's answer.

D. Harvatis Jul 13, 2015:

In none of these references does "genetic lineage" describe a class of tumours, which is what Spyros' query is about.

Peter Close Jul 13, 2015:

Genetic Lineage In support of Ourania’s answer, please see the following links:

May 5, 2010 - Defining the pathways through which tumors progress is critical to our ..... In these homogenous tumors, a more detailed genetic lineage is
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904844/

Genetic lineage markers for identifying glioma cancer stem ...
http://www.nature.com/scibx/journal/v5/n32/full/scibx.2012.8...

Genetic lineage labeling with fluorescent reporter alleles allows for the identification of epithelial-derived cells within tumors. This protocol describes a method to ...
http://cshprotocols.cshlp.org/content/2015/5/pdb.prot078287

Aug 30, 2014 - The study of single cancer cells has transformed from qualitative ... were found to have diverged from a common genetic lineage [45].
http://www.genomebiology.com/2014/15/8/452

And very many others that can be seen by Googling: "genetic lineage" (with the inverted commas)