SCC just gives you the cell type that has gone bad. I.e. the squamous cells.
It does not tell how these cells arrived at the dark side. (There are many way screwing up a cell, it is a wonder they actually work especially if you consider the numbers and the fact that they must constantly change)
That is to say not all SCC are the same. Some respond to MAB treatments while others do not.
For example; only around 20-30% of breast cancers can respond to herceptin, were a growth factor is over expressed. .... and there are also different ways that a growth factor can get over expressed/overactive too.
Back to SCC, there are chromosomal abnormalities (translocation, detetions etc), but in cancer cells things go haywire because they are not normal anymore. Therefore it may be that some of these abnormalities are a consequence (but not the cause) of a loss of normal cellular control. Some of that you can see with FISH etc but I doubt very much that this is done routinely!
Also, this is just one side then there is also the immune system that may or may not help fighting this.

This is a gross simplification, and I will not even pretend that I am current in this. What you really need is to talk to a cancer geneticist that specializes in SCC.
On the other hand to put is bluntly: it is what it is. The treatment is essentially fairly standard, we are not at the point of (very) individualized medicine.

M

You might be interested in this:
The Journal of Laryngology & Otology (2009), 123 : 266-272 Cambridge University Press