The finding that field changes frequently occur in TAM of
HNSCC patients creates a different view on tumor excision
margins that contain molecularly altered cells (93, 94). The
conclusion that the margin is tumor positive if it shows the
presence of genetically altered cells does not necessarily hold
true for every molecular marker used. The molecular marker
used has to be specific for that particular tumor. For example,
the observation that the same p53 mutation is present in the
margin (95) as well as as in the tumor might be useful; however,
the detection of overexpression of eIF4E in the margins (73) is
not specific for that tumor and more likely reflects a field
change caused by smoking.
Most field changes appear to be induced by smoking,
which implies carcinogen-induced field cancerization rather
than field cancerization due to migrated transformed cells. We
also conclude that almost no remote multiple tumors develop
due to migration of tumor cells. They seem to develop independently
as a result of the continuous carcinogenetic influence
of alcohol and/or tobacco. Therefore, patients with a HNSCC
should be advised to quit smoking to reduce the risk of the
development of MPTs, especially because HNSCC patients
seem to be more susceptible (9, 96) to tumor development than
cancer-free smokers.