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Generally, the
benefits
of RT greatly
outweigh risks
for tumor induction!
(improvements are needed, increased survival).
Second tumor incidence far from
high dose areas
is often relatively low (non-
IMRT).
Depending on
tissue/primary tumor
,… the risk may increase, level off, or
decrease at high dose.
If probability of tumor induction levels off, or decreases for higher doses,
tumor induction
may increase for IMRT and rotational therapy
.
High energy
photon beams (>10 MV)
may result in enhanced tumor
induction due to neutron peripheral dose.
Uncertainty in epidemiological data
: even studies based on large databases
of cancer registries (~100.000 patients) may have conflicting outcome on
second cancer incidence. More/better data is needed, e.g. to predict the impact
of new techniques such as IMRT or VMAT.
49
Clinical lessons - Discussion