You could theoretically subclassify cancers all the way down to individual gene mutations, and even then there is heterogeny within one cancer itself. That is the idea behind "personalized medicine" though it's being distorted by hype.
However, medicine is practical, and tries to draw boundaries where different therapies help differently or where there are different pathophysiology going on.
The article was able to draw a new additional boundary. Its relevance is yet to be confirmed with its phenotype or druggability. If it turns out to be useful either in predicting therapy or outcome, it'll stick and oncologists will learn it.
This process has already been repeated a lot in the hematological cancers, where previously cancers like "Hodgkin's lymphoma" have been subdivided as we made new treatments and discovered the individual pathways.
However, medicine is practical, and tries to draw boundaries where different therapies help differently or where there are different pathophysiology going on.
The article was able to draw a new additional boundary. Its relevance is yet to be confirmed with its phenotype or druggability. If it turns out to be useful either in predicting therapy or outcome, it'll stick and oncologists will learn it.
This process has already been repeated a lot in the hematological cancers, where previously cancers like "Hodgkin's lymphoma" have been subdivided as we made new treatments and discovered the individual pathways.