Methods of screening a sample for a predisposition for forming an EGFR-associated cancer and the presence of EGFR (v3) contained therein are described. The methods include the steps of obtaining a sample containing a plurality of cells and hybridizing a first set of labeled chromosomal probes and a second set of labeled chromosomal probes to the sample. The first set of labeled chromosomal probes specific to chromosome 7, and the second set of labeled chromosomal probes is a labeled EGFR(v3)-probe. The first and second sets of labeled chromosomal probes include different labels to permit identification of the first and second sets of labeled chromosomal probes hybridized to the sample. The method includes calculating the number of signals of the first and second sets labeled chromosomal probes on an individual cell basis and determining a predisposition for forming an EGFR-associated cancer and the presence of EGFR (v3) contained therein based upon those calculations.