Table 1.

Mutations classified by their putative role in cancer. Gray boxes indicate mutations whose understanding may be impeded by the driver/passenger paradigm. The two upper boxes can be distinguished using non-cancer samples because mutations which are both advantageous and predisposing will show high relative risk, whereas mutations which are only advantageous will show little or no elevation in relative risk. Similarly, the two lower boxes can be distinguished because mutations which are predisposing but not advantageous, while they tend to be uncommon, will show elevated relative risk when they do occur, whereas mutations which are neither advantageous nor predisposing will show no elevation in relative risk.

	Tends toward invasion and metastasis (“predisposing”)	Does not tend toward invasion and metastasis (“non-predisposing”)
Growth advantage (“advantageous”)	Drivers Elevated relative risk	Drivers? CDKN2A in esophageal adenocarcinoma Notch1 in skin Non-elevated relative risk
No growth advantage (“non-advantageous”)	Passengers? BRCA2, MSH2 Elevated relative risk	Passengers Non-elevated relative risk