Table 2.
Biomarker Analysis Results
| Assay | Ethnicity Group |
Analysis |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| African American (n = 53) |
White (n = 102) |
UnivariateP | Multivariate |
||||||
| No. | % | No. | Total No. | % | P | OR | 95% CI | ||
| EGFR mutation–positive | 1 | 2 | 15 | 89 | 17 | .005 | .022 | 11.36 | 1.41 to 90.91 |
| KRAS mutation–positive | 12 | 23 | 16 | 76 | 21 | .83 | .409 | 1.48 | 0.59 to 3.74 |
| EGFR FISH–positive* | 27 | 51 | 33 | 102 | 32 | .024 | .018 | 2.51 | 1.17 to 5.37 |
| Polysomy (5) | 21 | 40 | 20 | 102 | 20 | .007 | |||
| Amplification (6) | 6 | 11 | 13 | 102 | 13 | .798 | |||
Abbreviations: OR, odds ratio; EGFR, epidermal growth factor receptor; KRAS, v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog; FISH, fluorescent in situ hybridization.
*
For the FISH score, two readers independently scored 50 tumor cells in at least three tumor areas per specimen. Scores of 5 and 6 were considered FISH-positive scores. A FISH score of 5 required four or more copies in ≥ 40% of cells; a FISH score of 6 required gene amplification, which was defined by the presence of EGFR gene clusters, by a gene/chromosome ratio per cell of two or greater, or by 15 or more copies of EGFR in ≥ 10% of analyzed cells. Discrepancies between readers were resolved by a third reader.